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(MOO Keiqr P( , HsTz02(-00 543 4 Design for �i CodeAcceptance _ f , , , ,, , I Prescriptive Residential Wood Deck Construction Guide cG ��Ce® Based on the 2015 International Residential Code V pEC• . 2.021 Chi _ D,, ON guard decking gVILD ledger board— blocking , fasteners existing house floor construction 4111111%400„ ---- 11 --, "�`vi guard post //'� ledger board attachment `�� � �' attachment to ggi /,b ,14,000,% � existing house rim joist 4 %:� joists beam post-to-beam connection (flush, tight bearing) footing joist-to-beam post connection Where applicable, provisions and details contained in this document are based on the International Residential Code (IRC) [bracketed text references applicable sections of the IRC]. Prescriptive construction methods recommended meet or exceed minimum requirements of the IRC. Provisions that are not found in the IRC are recommended as good industry practice. Where differences exist between provisions of this document and the IRC, provisions of the IRC shall apply.This document is not intended to preclude the use of other construction methods or materials.All construction and materials must be approved by the authority having jurisdiction. Every effort has been made to reflect the language and intent of the IRC. However, no assurance can be given that designs and construction made in accordance with this document meet the requirements of any particular jurisdiction. Copyright© 2018 American Wood Council 2 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE CONTENTS MINIMUM REQUIREMENTS&LIMITATIONS 2 LEDGER BOARD FASTENERS 15 DECKING REQUIREMENTS 3 NON-LEDGER DECKS -VERTICAL LOADS 17 JOIST SIZE 3 DECK LATERAL LOADS 17 BEAM SIZE&ASSEMBLY REQUIREMENTS 5 GUARD REQUIREMENTS 19 DECK FRAMING PLAN 8 GUARD POST ATTACHMENTS 19 JOIST-TO-BEAM CONNECTION 9 STAIR REQUIREMENTS 20 JOIST HANGERS 9 STAIR HANDRAIL REQUIREMENTS 22 POST REQUIREMENTS 10 STAIR FOOTING REQUIREMENTS 22 RIM JOIST REQUIREMENTS 11 STAIR LIGHTING REQUIREMENTS 22 FOOTINGS 11 FRAMING AT CHIMNEY OR BAY WINDOW 23 LEDGER ATTACHMENT REQUIREMENTS 13 PROHIBITED LEDGER ATTACHMENTS 15 MINIMUM REQUIREMENTS& LIMITATIONS • All screws,bolts,washers, nuts, and nails for use 1. This document applies to single level residential with preservative treated wood shall be hot-dipped wood decks that are attached to the house to resist zinc-coated galvanized steel, stainless steel,silicon lateral forces. [R507.2.4] bronze,or copper.Hot-dipped galvanized 2. Overall deck length shall be equal to or less than fasteners shall meet the requirements of ASTMA overall deck width. See DECK FRAMING PLAN for 153, Class D for fasteners /8 diameter and definition of deck length and width. smaller orClass C for fasteners with diameters over /g". Stainless steel driven fasteners shall be 3. Minimum post size is 6x6 nominal and maximum post in accordance with the material requirements of height shall be in accordance with Table 4. ASTMF 1667. 4. All lumber shall be identified by the grade mark of, • Fasteners other than nails and timber rivets shall or certificate of inspection issued by, an approved be permitted to be of mechanically deposited zinc- lumber grading or inspection bureau or agency coated steel with coating weights in accordance (www.alsc.org).All lumber and glued laminated with ASTMB 695, Class 55,minimum. timber shall be a naturally durable species(such as Redwood or Western Cedars where 90 percent or • All connectors(joist hangers, cast-in-place post more of the width of each side is heartwood); or be anchors, etc.) shall be galvanized or shall be preservatively treated with an approved process in stainless steel.Hardware to be hot-dipped prior to accordance with American Wood Protection fabrication shall meet ASTMA 653, G-185 Association standards(Table 1) [R317 and R318]. coating. Hardware to be hot-dipped galvanized All lumber in contact with the ground shall be after fabrication shall meet ASTMA 123. approved preservative treated wood suitable for • Fasteners and connectors exposed to salt water or ground contact. [R317.1.2] All cuts shall be field located within 300 feet of a salt water shoreline treated with an approved preservative(such as shall be stainless steel grade 304 or 316. copper naphthenate)[R402.1.2]. • Fasteners and connectors shall be of the same 5. All nails shall meet the requirements of ASTMF corrosion-resistant material. 1667. Threaded nails as stated in this document • Other coated or non-ferrous fasteners or hardware include helical(spiral)and annular(ring-shank) shall be approved by the authority having nails.Wood screws shall meet the requirements of jurisdiction. ANSI/ASME B18.6.1. Bolts and lag screws shall meet the requirements of ANSI/ASME B18.2.1. 8. Decks supporting large concentrated loads such as 6. Throughout this document, 1/2" diameter bolts and hot tubs are beyond the scope of this document. lag screws are specified for various connections. 9. This document does not apply to decks which will Edge distance and spacing requirements are based experience snow loads,snow drift loads,or sliding on 1/2" diameter fasteners. If larger(or smaller) snow loads that exceed 40 psf. fasteners are specified, edge distance and spacing 10. Lateral load resistance is limited to the prescriptive shall be adjusted. provisions of R507.2.4 of the IRC. Alternative loads 7. To resist corrosion, the following is required and detailing shall be approved by the authority [R317.3]: having jurisdiction. American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 3 11. Flashing shall be corrosion-resistant metal [R703.8] 12. Decks shall not be used or occupied until final of minimum nominal 0.019-inch thickness or inspection and approval is obtained. approved non-metallic material. Aluminum should 13. This document is not intended to preclude the use of not be used in direct contact with lumber treated other construction methods or materials not described with preservatives that contain copper such as ACQ, herein. Copper Azole, or ACZA. Table 1. Common Species and Use Categories for Decay Resistance.' Species Above Ground Ground Contact Southern Pine X X N Douglas Fir-Larch X X Hem-Fir X X I— m SPF X Ponderosa Pine X X Red Pine X X m a_ Redwood X X Western Cedars X Tu 2- Redwood X z 0 Western Cedars X 1.Use categories listed in Table 1 are based on the American Wood Protection Association(AWPA)Book of Standards. 2.Above Ground—UC3B; Ground Contact—UC4A. 3.Naturally durable species with 90%heartwood in width on each side need not be treated per minimum requirements. DECKING REQUIREMENTS authority having jurisdiction; however, connections All decking material shall be composed of dimension equivalent to those shown for lumber or span rated lumber(2"nominal thickness)or span rated decking in decking are assumed. accordance with the American Lumber Standard Committee Policy for Evaluation of Recommended JOIST SIZE Spans for Span Rated Decking Products (November 5, The span of a joist, L, is measured from the face of 2004). Attach decking to each joist with 2-8d threaded support at one end of the joist to the face of support at nails or 2-#8 screws. Space decking boards the other end of the joist and does not include the length approximately '/8" apart. See Figure 11 for decking of the overhangs, Lo. Use Table 2 to determine connection requirements at the rim joist. Decking allowable joist span, LJ,based on lumber size and joist placement may range from an angle perpendicular to the spacing. Joist span, L, must be less than or equal to joists to an angle of 45 degrees to the joists. Each allowable joist span, Li. Overhang length is the lesser of segment of decking must bear on a minimum of 3 joists allowable overhang, Lo, or one fourth the joist span, L/4. (or 3 supports). See Figure 1 and Figure 2 for joist span types. Decking not meeting these requirements may be substituted when the product has been approved by the American Wood Council ... ;, 4 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Table 2. Maximum Joist Spans and Overhangs.' Joist Spacing (o.c.) 12" 16" 24" 12" 16" 24" r Species Size Allowable Span2 (LJ) Allowable Overhang3(Lo) 2x66 9'- 11" 9' -0" 7'-7" 1' -0" 1' - 1" 1'- 3" 2x8 13'- 1" 11'- 10" 9'-8" 1'- 10" 2'-0" 2' -4" Southern Pine 2x10 16' -2" 14'-0" 11'-5" 3' - 1" 3' -5" 2' - 10" 2x12 18'- 0"' 16'-6" 13'-6" 4'-6" 4'-2" 3'-4" 2x66 9'-6" 8'-4" 6' - 10" 0'- 11" 1' -0" 1'-2" Douglas Fir- 2x8 12'-6" 11'- 1" 9'- 1" 1' -8" 1'- 10" 2'-2" Larch, Hem-Fir, Spruce-Pine Firs 2x10 15'-8" 13'-7" 11'- 1" 2'- 10" 3'-2" 2'-9" 2x12 18'-0"' 15' -9" 12'- 10" 4' -4" 3' - 11" 3'- 3" 2x66 8'- 10" 8'- 0" 6' - 10" 0' -9" 0'- 10" 0'- 11" Redwood, 11'-8" 10'-7" 8'-8" 1'- 5" 1'-7" 1'-9" Western Cedars, 2x8 Ponderosa Pines, 2x10 14'- 11" 13'-0" 10'-7" 2' -5" 2' -7" 2' -8" Red Pines 2x12 17'-5" 15'- 1" 12'-4" 3' -7" 3'-9" 3'- 1" 1.Assumes 40 psf live load, 10 psf dead load, No.2 grade,and wet service conditions. 2.Assumes U360 deflection. 3.Maximum allowable overhang cannot exceed U4 or'/.of actual main span.Assumes cantilever length/180 deflection with 220 lb point load(See Figure 1A and Figure 2). 4. Incising assumed for Douglas Fir-Larch,Hem-Fir,and Spruce-Pine-Fir. 5. Design values based on northern species with no incising assumed. 6.Ledger shall be a minimum of 2x8 nominal.Joists and rim joists to which guard posts are attached shall be a minimum of 2x8 nominal. 7.Joist length prescriptively limited to 18'-0"for footing design. Figure 1A. Joist Span —Joists Attached at House and Bearing Over Beam. existing wall - optional overhang joist xrE.X --nl-->zo5:Il 1�C i lc -If 1f> rim joist I IL. -- blocking (at overhanging I/ joists only) f (,\I\ joist hanger fy ledger board beam(flush tight bearing) --- post L.o or U4 t maximum �-- Joist span(LsL�) overhang See Table 2 American Wood Council W .4, PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 5 Figure 1B. Joist Span —Joists Attached at House and to Side of Beam. existing wall - joist L�III�I11�I1�Zl� /ti beam* r joist hanger - � ledger board *Note: beam depth must be equal to or greater than joist post �. depth if joist hangers are used joist span(LSL j) See Table 2 / h Figure 2. Joist Span — Non-Ledger Deck. existing wall --I optional overhang optional overhang rim joist blockingonly) overhanging I(' rim joist beam(flush 4 ` tight bearing) t joist beam (flush tight bearing) post post Lo or U4 joist span(LsLJ) Lo or U4 -•0-- maximum maximum overhang See Table 2 overhang BEAM SIZE &ASSEMBLY REQUIREMENTS Joists shall not frame in from opposite sides of the same Deck beam spans shall be in accordance with Table 3 beam. See JOIST-TO-BEAM CONNECTION details, and can extend past the post face up to LB/4 as shown in Figure 6. Figure 3. Joists may bear on the beam and extend past Where multiple 2x members are used, the deck's beam is the beam face up to the lesser of Lo or L/4 as shown in assembled by attaching the members identified in Table Figures lA and 2, or the joists may attach to the side of 3A in accordance with Figure 4 [Table R602.3(1)]. the beam with joist hangers as shown in Figure 1B. American Wood Council 6 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Table 3A. Dimension Lumber Deck Beam Spans (LB)t Supporting a Single Span of Joists with or without Overhangs. Joist Spans (L) Less Than or Equal to: Species Size4 6' 8' 10' 12' 14' 16' 18' 2-2x6 6' -8" 5' -8" 5' - 1" 4' -7" 4' -3" 4' -0" 3'- 9" 2-2x8 8'-6" 7'-4" 6'-6" 5' - 11" 5' -6" 5' - 1" 4'-9" 2-2x10 10' - 1" 8' -9" 7' -9" 7' - 1" 6' -6" 6'- 1" 5'-9" Southern Pine 2-2x12 11' - 11" 10'-4" 9'-2" 8' -4" 7'-9" 7' -3" 6'-9" 3-2x6 7'- 11" 7' -2" 6' -5" 5' - 10" 5' -5" 5' - 0" 4'- 9" 3-2x8 10' -7" 9' -3" 8' -3" 7'-6" 6'- 11" 6' -5" 6'- 1" 3-2x10 12'-9" 11'-0" 9' -9" 8' -9" 8'-3" 7' -8" 7'- 3" 3-2x12 15' -0" 13' -0" 11' -7" 10' -6" 9' -9" 9' - 1" 8'-7" 3x6 or 2-2x6 5'- 2" 4'- 5" 3'- 11" 3' -7" 3'-3" 2'- 10" 2'-6" 3x8 or 2-2x8 6'-7" 5'- 8" 5'- 1" 4'-7" 4'-3" 3'- 10" 3'- 5" Douglas Fir- 3x10or2-2x10 8'- 1" 7'-0" 6'-3" 5'-8" 5'-3" 4'- 10" 4'-5" Larch2, Hem- 3x12 or 2-2x12 9' -5" 8'-2" 7'-3" 6' -7" 6' - 1" 5' -8" 5'-4" Firz, Spruce- , 4x6 6'-2" 5'-3" 4'-8" 4' -3" 3'- 11" 3'-8" 3'-5" Pine-Fir Redwood, 4x8 8'- 2" 7' -0" 6'-3" 5'-8" 5'- 3" 4'- 11" 4'-7" Western 4x10 9'-8" 8'-4" 7'-5" 6' -9" 6'- 3" 5' - 10" 5'- 5" Cedars, 4x12 11' -2" 9' -8" 8' -7" 7' - 10" 7' - 3" 6' -9" 6'-4" Ponderosa Pine3, Red 3-2x6 7'- 1" 6'-5" 5' -9" 5'- 3" 4'- 10" 4' -6" 4'-3" Pine3 3-2x8 9' -5" 8'-3" 7'-4" 6' -8" 6'-2" 5' -9" 5'- 5" 3-2x10 11'-9" 10'-2" 9'- 1" 8' -3" 7'- 7" 7' - 1" 6'- 8" 3-2x12 13'- 8" 11'- 10" 10' -6" 9'- 7" 8' - 10" 8'- 3" 7' - 10" 1.Assumes 40 psf live load, 10 psf dead load, L/360 simple span beam deflection limit,cantilever length/180 deflection limit,No.2 grade, and wet service conditions. 2.Incising assumed for Douglas Fir-Larch,Hem-Fir,and Spruce-Pine-Fir. 3.Design values based on northern species with no incising assumed. 4.Beam depth must be equal to or greater than joist depth if joist hangers are used(see Figure 6,Option 3). American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 7 . Table 3B. Glued Laminated Timber Beam Spans (LB)1 Supporting a Single Span of Joists with or without Overhangs. Joist Spans (L) Less Than or Equal to: Stress Class2 Width3 Depth': 6' 8' 10' 12' 14' 16' 18' 9-1/2" 12'-2" 10'-6" 9'-4" 8'-6" 7'-10" 7'-4" 6'-1 1" 3-1/2" 11-7/8" 15'-2" 13'-1" 11'-8" 10'-8" 9'-10" 9'-2" 8'-8" Balanced or Unbalanced 20E-1.5E 14" 17'-10" 15'-5" 13'-9" 12'-7" 11'-7" 10'-10" 10'-2" And Higher Grade 11-7/8" 18'-0"5 16'-8" 14'-10" 13'-7" 12'-6" 11'-8" 11'-0" Cedar 5-1/4" 14" 18'-0"5 18'-0"5 17'-6" 15'-11" 14'-9" 13'-9" 13'-0" 16" 18'-0"5 18'-0"5 18'-0"5 18'-0"5 16'-1 0" 1 5'-9" 14'-1 0" 9-1/2" 13'-1 1" 12'-1" 10'-9" 9'-10" 9'-1" 8'-6" 8'-0" 3-1/2" 11-7/8" 17'-5" 15'-1" 13'-5" 12'-3" 11'-4" 10'-7" 10'-0" Unbalanced 24F-1.8E 14" 18'-0"5 17'-9" 15'-10" 14'-5" 1 3'-4" 1 2'-6" 11'- 9" Douglas Fir-Larch or Southern Pine 11-7/8" 18'-0"5 18'-0"5 17'-1" 15'-7" 14'-5" 13'-6" 12'-8" 5-1/4" 14" 18'-0"5 18'-0"5 18'-0"5 18'-0"5 17'-0" 1 5'-1 0" 14'-1 1" 16" 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 1 7'-0" 9-1/2" 1 3'-1 1" 12'-7" 11'-8" 11'-0" 1 0'-5" 9'-1 1" 9'-7" 3-1/2" 11-7/8" 17'-5" 15'-10" 14'-8" 13'-9" 13'-1" 12'-6" 12'-0" Balanced 24F-1.8E 14" 18'-0"5 18'-0"5 17'-4" 16'-3" 15'-5" 14'-9" 14'-2" Douglas Fir-Larch or ,.s ��s Southern Pine 11-7/8" 18-0 18-0 17-4 16-3 15-5 14-9 14-2 5-1/4" 14" 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 17'-6" 16'-9" 16" 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 18'-0"5 1.Assumes 40 psf live load, 10 psf dead load, L/360 simple span beam deflection limit,cantilever length/180 deflection limit.Glued laminated timber shall be of naturally durable species or treated with an oil-borne or water-borne preservative in accordance with AWPA U1.See MINIMUM REQUIREMENTS&LIMITATIONS.Spans for glued laminated timber beams not treated with oil-borne preservatives shall be multiplied by 0.89. 2. Preservative treated structural composite lumber of equal or greater capacity can be substituted. 3.Beam widths of 3-1/8"or wider can be used for the tabulated 3-1/2"width,and beam widths of 5-1/8"or wider can be used for the tabulated 5-1/4"width. 4.Beam depth must be equal to or greater than joist depth if joist hangers are used(see Figure 6,Option 3). 5.Beam span prescriptively limited to 18'-0"for footing design. Figure 3. Beam Span. joists above optional overhang(may occur at each end) IUI IV , , IV! 11/1 IAI IAI A N X IAI Al P 11 l r Y-- --L I I I I L J beam beam splice • (if needed) -»-- post,typical at interior post locations _______ _; LB/4 max. beam span(LB): beam span(LB): LB/4 max. �— overhang See Table 3 See Table 3 overhang American Wood Council 8 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Figure 4. Beam Assembly Details. 10d threaded nail or#10 wood 2 threaded nails or screws at each end or screw z3"long,staggered in splice end;splices shall be located only over 2 rows interior posts(Figure 3) If a beam is constructed with 3-members,1 16" attach each outside member to the inside typical member as shown here. DECK FRAMING PLAN The overall deck length shall be equal to or less than the A framing plan shows the width, length,joist and beam overall deck width. Stairs and stair landings shall not be layout; the location of the ledger board,posts,and included in determining the overall deck length or width. footings; and the type, size, and spacing of the ledger See Figure 5 for an example of a typical deck framing board fasteners. plan. Figure 5. Typical Deck Framing Plan. Lumber species: (see Table 1) rfNNN.-1 f o jhyr�j� I- ZI_ \c1 I_ .1 ' I ,Bay Window/ \ x ledger o board with Y2"dia. HV L /J o bolts/lag screws/anchors N V I.C. CTI @ "O.C. z a it N - I- -1 ai a) (see Table 5) a o co joist hanger: lbs �, 1 (see Table 3A) c E X c n -- 3 a I doub e or triple trimmer hanger: lbs c N O a, 0 J U `o m (see Table 7) @ o x trimmer>o .c a m 0 1:,. j (see Figure 35)o c> \� rim joist x i �� min. ��~� 0 / 6x6 post / ' q l L 1 stair stringers: / It s // cut or solid " v o, `/ - • - span: x R (see Figure 28) ` tdE - o treads: x (see Table 6) LB/4 max. beam span(LB):see Table 3 single, LB/4 max. overhang overhang double, or triple_x_;LB= '- ' overall deck width: - " American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 9 JOIST-TO-BEAM CONNECTION must have a minimum capacity of 100 lbs in both uplift Each joist shall be attached to the beam as shown in and lateral load directions. Joists may also attach to the Figure 6. Joists may bear on and overhang past the beam side of the beam with joist hangers per Option 3. Joists face the lesser of Lo or L/4 when Option 1 or Option 2 is shall not frame in from opposite sides of the same beam. used to attach the joist to the beam and blocking is See JOIST HANGERS for more information. Hangers, provided between joists at beam bearing. Mechanical clips, and mechanical fasteners shall be galvanized or fasteners or hurricane clips used, as shown in Option 2, stainless steel(see MINIMUM REQUIREMENTS). Figure 6. Joist-to-Beam Detail. 3-8d threaded OPTION 1 OPTION 2* OPTION 3* toe nails mechanical (2 on one side, I fastener or top of beam or 1 on the other) hurricane clip lost ledger and joist WA hanger must be at same :!>, 1 /5 elevation 1 7 beam Al 11 *see manufacturer's recommendations for additional requirements JOIST HANGERS Figure 7. Typical Joist Hangers. Joist hangers, as shown in Figure 7, shall have a depth of joist hanger with inside flanges at least 60%of ledger or beam depth. Each hanger shall have a minimum vertical capacity in accordance with Table 3A. The joist hanger shall be selected from an ,.,/--i 7 approved manufacturer's product data based on the `~ dimensions of the joist or header it is carrying. Joist hangers and fasteners shall be corrosion resistant(see 11(11111111 MINIMUM REQUIREMENTS).Use joist hangers with inside flanges when clearances tothe edge of the beam or ledger board dictate. Do not use clip angles or brackets to support joists. Table 3A. Joist Hanger Vertical Capacity. Joist Size Minimum Capacity, lbs 2x6 400 2x8 500 . 2x10 600 2x12 700 American Wood Council 10 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE , POST REQUIREMENTS Figure 8B. Alternate Approved Post-to-Beam • All deck post sizes shall be 6x6(nominal)or larger, and Post Cap Attachment. the maximum height shall be in accordance with Table 4 solid sawn or and measured from grade or top of foundation, '"" --- multi-ply beam whichever is highest,to the underside of the beam. .�_----.._..___ Under prescriptive limits of this document, 8x8 nominal II I /' posts can be substituted anywhere in Table 4 but are `��3�11 limited to a maximum height of 14'-0". Posts shall be it t centered on footings. Cut ends and notches of posts shall ,.iiNo 1,4,�: be field treated with an approved preservative (such as ,I.:' ' ; copper naphthenate) [R402.1.2]. The beam shall be o'-� IPost � i i " `� attached to the post by notching as shown in Figure 8A 6x6 min. ° � ! P .�,'0 l;' y or by providing an approved post cap to connect the beam and post as shown in Figure 8B. All 3-ply beams ° shall be connected to the post by a post cap. All through- bolts shall have washers under the bolt head and nut. Attachment of the beam to the side of the post without notching is prohibited(see Figure 9). Figure 9. Prohibited Post-to-Beam Attachment Condition. Provide diagonal bracing parallel to the beam at each corner post greater than 2'-0" in height as shown in Figure 10. Diagonal bracing is prohibited on center posts. Bracing shall be fastened to the post at one end and the beam at the other with 'A"diameter lag screws. ■_■ For non-ledger decks, (see Figure 21) diagonal bracing 1110 Through-bolts, Note:Support of beams WI may be omitted at the beam and posts adjacent to the l! lag screws,or fasteners only is prohibited. house. r,, li nails, Bearing is required.See I(l �1 Figure 8A. Figure 8A. Post-to-Beam Attachment • _p Requirements. (2)Yz"diameter single 3"or 4" I through-bolts nominal or double with washers 2'"nominal beam HAN 4' Z2" beam must f1UM 11 " Figure 10. Diagonal Bracing. bear fully on notched 6x6 6x6 min. 111111111111111 Ili 1II.I ENN Z2Yz" IT r,),\ beam cueit'' a 2x4,typical (1)1/2"diameter El ,_ lag screw with II ir tea" a) washers,typical • Typical Post At Splice ■ 111 ■ DIAGONAL BRACING PARALLEL TO BEAM Note: Diagonal Bracing is prohibited on center posts. American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 11 RIM JOIST REQUIREMENTS Attach a continuous rim joist to the ends of joists as shown in Figure 11. Attach decking to the rim joist as shown in Figure 11. For more decking attachment requirements, see DECKING REQUIREMENTS. Figure 11. Rim Joist Connection Details. joists secure decking to top of rim joist with 10d threaded nails or#10 x 3" minimum wood screws©6"o.c. ° Pri4 ,jattach rim joist to end of each joist with • (3) 10d threaded nails or(3)#10 x 3" minimum wood screws rim joist FOOTINGS [R4031 capacity shall be determined by a soils investigation. See Figure 12 and Table 4 for footing size, footing DECK FOOTINGS CLOSER THAN 5'-0" TO AN thickness, and post attachment options and requirements. EXTERIOR HOUSE FOUNDATION WALL MUST All footings shall bear on undisturbed soil at least 12 BEAR AT THE SAME ELEVATION AS THE inches below the undisturbed ground surface or below FOOTING OF THE HOUSE FOUNDATION. the frost line,whichever is deeper. Contact the authority Do not construct footings over septic systems or leach having jurisdiction to determine the specified frost line. fields, utility lines,or enclosed meters. Contact local Bearing conditions shall be verified in the field by the utilities(call 811)before digging. building official prior to placement of concrete. Where Pre-manufactured post anchors shall be galvanized or the building official determines that in-place soils with stainless steel. See MINIMUM REQUIREMENTS. an allowable bearing capacity of less than 1,500 psf are likely to be present at the site,the allowable bearing American Wood Council 12 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Table 4. Post Height for 6x65 and Footing Sizes for all Posts. Post Heights' Footing Sizes2 J J t E ai M y , _ c �`a N C a c = c L ++ Q. C. i J a) ' o d u) o w 0 Y co cod _ 16 2 N a> p 0u. C� ai p o a li m a 'a m = a) 0 a O o l a° cn o 510' 14' 14' 14' 14' 14' 18" 16"x16" 7" 6' 514' 14' 14' 14' 14' 14' 21" 18"x18" 8" 518' 14' 14' 12' 14' 11' 24" 21"x21" 10" 510' 14' 14' 14' 14' 14' 20" 18"x18" 8" 8' 514' 14' 14' 14' 14' 11' 24" 21"x21" 10" 518' 14' 13' 11' 12' 8' 27" 24"x24" 11" 510' 14' 14' 14' 14' 12' 23" 20"x20" 9" 10' 514' 14' 13' 11' 13' 8' 27" 24"x24" 11" 518' 12' 11' 8' 11' 2' 31" 27"x27" 13" 510' 14' 14' 12' 14' 10' 25" 22"x22" 10" 12' 514' 13' 12' 9' 11' 5' 30" 26"x26" 13" 518' 11' 9' 6' 9' 2' 34" 30"x30" 15" 510' 14' 13' 11' 13' 8' 27" 24"x24" 11" 14' 514' 11' 10' 7' 10' 2' 32" 29"x29" 14" 518' 9' 8' 2' 8' NP 37" 33"x33" 16" 510' 13' 12' 10' 12' 6' 29" 26"x26" 12" 16' 514' 10' 9' 5' 9' 2' 35" 31"x31" 15" 518' 7' 5' 2' 7' NP 40" 35"x35" 18" 510' 12' 11' 8' 11' 2' 31" 27"x27" 13" 18' 514' 9' 8' 2' 8' NP 37" 33"x33" 16" 518' 5' 2' 2' 6' NP 42" 37"x37" 19" 1.Assumes 40 psf live load, 10 psf dead load,LB/4 and L,/4 overhangs, No 2.grade and wet service conditions. 2.Assumes 1,500 psf soil bearing capacity and 150 pcf concrete.Value may be multiplied by 0.9 for corner posts. 3. Incising assumed for Douglas Fir-Larch,Hem-Fir,and Spruce-Pine-Fir. 4.Assumes 2,500 psi compressive strength of concrete.Coordinate footing thickness with post base and anchor requirements. 5.8x8 nominal posts may be substituted anywhere in Table 4 to a maximum height of 14'. American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 13 Figure 12. Typical Footing Options. Cut ends of posts posts must be shall be field treated centered on footing with an approved =\— —°.— preservative(such as copper ) "diameter pre-manufactured rod Ipost base naphthenate) with post anchor ri 12 ts**-'''Z" \4:d " 1=11 i=II I a: 1 e e ea • . 1 12"diameter a . i e a e 12" a cone.sem 4"min. min. dd ° • a 4 a 1 - If 4: 4 . • '� 4 per a ��.. .:e' 4 4 ` : Table 4 6" 6" frost depth t per Table 4 1—.-- per Table 4 i-••--- •{ per Table 4 .4_ 4"min. per Table 4 —.— footings must bear gravel on undisturbed soil LEDGER ATTACHMENT REQUIREMENTS 13A). Many new homes constructed with wood I-joists IR5071 include 1" or thicker laminated veneer lumber(LVLas GENERAL: Attach the ledger board,which shall be band joists (or rim joists)that can support the attachment equal to or greater than the deck joist depth but less than of a deck (see Figure 14).However, some older homes or equal to the house band or rim joist depth,to the might be constructed with band boards that are too thin house in accordance with Figures 14 and 15. The ledger (less than 1 )to support a deck. In such cases, anon- shall be a minimum nominal 2x8. When attachments are ledger deck or a full plan submission is required. made to the house band joist,the band joist shall be MANUFACTURED WOOD TRUSS: A metal plate capable of supporting the new deck. If this cannot be connected wood truss (MPCWT) is an engineered, verified or conditions at the house differ from the details prefabricated structural component designed for each herein, then either a non-ledger deck or full plan specific application. MPCWT's used in residential floors submission is required. See NON-LEDGER DECKS. are often installed with a 2x4 lumber"ribbon"at the SIDING AND FLASHING: House siding or the ends of the trusses (see Figure 13B)to tie the ends of the exterior finish system must be removed prior to trusses together. The ribbon board,by itself, is not installation of the ledger board.Approved corrosion intended to support the deck ledger and deck. Installing resistant flashing is required at any ledger board residential decks when the floor system for the house connection to a wall of wood framed construction(see uses MPCWT requires a standard detail provided by the MINIMUM REQUIREMENTS). See Figure 14 for truss designer, a non-ledger deck,or a full plan continuous flashing with drip edge. The threshold shall submission. Refer to the Technical Note—Attachment of be carefully flashed and caulked to prevent water Residential Deck Ledger to Metal Plate Connected intrusion due to splash from the deck or melting snow Wood Truss Floor System for special blocking details and ice. and attachment requirements(www.sbcindustry.com). MANUFACTURED WOOD I-JOIST: The term"I- Joist"denotes manufactured wood"I"joists (see Figure American Wood Council 14 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE • • Figure 13A. Wood I-Joist Profile. Figure 13B. Metal Plate Connected (MPC) Wood Floor Trusses with a 2x4 Lumber "Ribbon" at the Ends of the Trusses. 2x4 RIBBON BOARD - not intended for 'A " deck attachment _,- f/ ,--- /07 MPC FLOOR I '� ff TRUSSES 0 k,4#OA 10"),,ropio. 010 ,.► FOUNDATION WALL Figure 14. General Attachment of Ledger Board to Band Joist or Rim Joist. remove siding at ledger exterior sheathing ` prior to installation existing stud wall 1 threshold carefully flashed and caulked to prevent water intrusion existing 2x band joist ledger and joist flush on top or 1" minimum continuous flashing EWP rim joistillMi extending past joist � I/� hanger 2" min. 1 m rj. deck joist Jr 1-5/85" max." min. MI (1 111111.'- »} ■■■I: 1/2"diameter lag 2x floor joist, 2" min.��l screws or wood I joist, �"�1 through-bolts with or MPCWT washers a • • joist hanger existing • wall 2x ledger board; must be greater than or equal to the depth of the deck joist and no greater than the depth of the house band or rim joist Figure 15. Attachment of Ledger Board to Foundation Wall (Concrete or Solid Masonry). embed anchors per manufacturer • ., _,-recommendations to resist corrosion and decay, this area should be caulked • • 11111111111111111111 deck joist existing concrete G re• I • or solid masonry • t • • wall . blibb.. °r ..,,,,.� 1/2"diameter *Note: Blocks filled Al1MM approved expansion, with grout or epoxy,or adhesive concrete at • anchors with washers joist hanger anchor locations ° 9 for new construction 2x ledger board; must be greater than or equal to the size of the joist American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 15 , PROHIBITED LEDGER ATTACHMENTS Figure 18. No Attachment to House Overhang Attachments to exterior veneers(brick, masonry, stone), with Ledger. hollow masonry, and to cantilevered floor overhangs or bay windows are prohibited(see Figures 17 and 18). In such cases,the non-ledger deck is required(See NON- LEDGER DECKS). -"11(�1 fll Figure 17. No Attachment to or Through '14 ,, ` „ Exterior Veneers (Brick, Masonry, Stone). )1 14 ----,. :! ,,_,,Rit, i rfiyAllr ------ 4-- overhang rill orbay ,...,„ window`��-k r or nryey LEDGER BOARD FASTENERS lumber band joist(1-1/2" actual) or LVL rim joist bearing Only those fasteners noted below are permitted. LEAD on a sill plate or wall plate shall be constructed with 1/2" ANCHORS ARE PROHIBITED. lag screws or bolts with washers per Table 5 and Figure 19(see MINIMUM REQUIREMENTS). Deck ledger connection to band joist or rim joist.The connection between a deck ledger and a 2-inch nominal Table 5. Fastener Spacing for a Southern Pine, Douglas Fir-Larch, or Hem-Fir Deck Ledger or Band or Rim Joist and a 2-inch Nominal Solid-Sawn Spruce-Pine-Fir Band Joist or LVL Rim Joist.3,4,5,6,8 (Deck Live Load =40 psf, Deck Dead Load = 10 psf) Joist Span Rim Joist 6'-0" 6'-1" 8'-1" 10'-I" 12'-1" 14'-1" 16'-1" or and to to to to to to Band Joist less 8'-0" 10'-0" 12'-0" 14'-0" 16'-0" 18'-0" Connection Details On-Center Spacing of Fasteners 1/2' diameter lag screw' with 1" LVL 24� 18" 14" 12" 10" 9" 8" 1- 15/32" maximum sheathing /a LVL 28" 21" 16" 14" 12" 10" 9 1-1/2" Lumber 30" 23" 18" 15" 13" 11" 10" 1" LVL 24" 18" 14" 12" 10" 9" 8" '/Z'diameter bolt with 1-1/8" LVL 28" 21" 16" 14" 12" 10" 9" 15/32" maximum sheathing 1-1/" Lumber 36" 36" 34" 29" 24" 21" 19" 1/"diameter bolt with 15/32" maximum sheathing and 1-1/2" Lumber 36" 36" 29" 24" 21" 18" 16" 1/2' stacked washers2'7 1. The tip of the lag screw shall fully extend beyond the inside face of the band or rim joist. 2. The maximum gap between the face of the ledger board and face of the wall sheathing shall be'h". 3. Ledgers shall be flashed or caulked to prevent water from contacting the house band joist(see Figures 14 and 15). 4. Lag screws and bolts shall be staggered per Figure 19. 5. Deck ledgers shall be minimum 2x8 pressure-preservative-treated No.2 grade lumber,or other approved materials as established by standard engineering practice. 6. When solid-sawn pressure-preservative-treated deck ledgers are attached to engineered wood products(minimum 1"thick wood structural panel band joist or structural composite lumber including laminated veneer lumber),the ledger attachment shall be designed in accordance with accepted engineering practice.Tabulated values based on 300 lbs and 350 lbs for 1" and 1-1/8" LVL rim joist,respectively. 7. Wood structural panel sheathing,gypsum board sheathing,or foam sheathing shall be permitted between the band or rim joist and ledger.Stacked washers are permitted in combination with wood structural panel sheathing,but are not permitted in combination with gypsum board or foam sheathing.The maximum distance between the face of the ledger board and the face of the band joist shall be 1". 8. Fastener spacing also applies to Southern Pine,Douglas Fir-Larch,and Hem-Fir band or rim joists. American Wood Council 16 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Placement of lag screws or bolts in deck ledgers the deck ledger(see Figure 19). Proper installation of lag , The lag screws or bolts shall be placed as shown in screws or bolts shall be verified by the authority having Figure 19. The lag screws or bolts shall be staggered jurisdiction. from the top to the bottom along the horizontal run of Figure 19. Ledger Board Fastener Spacing and Clearances. stagger fasteners See Table 5 �, See in 2 rowsg Figure 14 for rim - / joist fastener spacing © © aU 5.5"*min.for 2x8 *Distance can be reduced to 4.5" 5"max. 6.5"min. for 2x10 if lag screws are used or bolt © © Q © 7.5"min. for 2x12 spacing is reduced to that of lag screws to attach 2x8 ledgers to 2x8 band joists(1/2" 2"min. lag screw, through-bolt,or ledger anchor with washer 3/4" min. stacked washers not permitted) Through-Bolts manufacturer's recommendations. All anchors must have Through-bolts shall have a diameter of'A". Pilot holes washers. for through-bolts shall be 17/32" to 9/16" in diameter. Through-bolts require washers at the bolt head and nut. Lag Screws Lag screws shall have a diameter of'A" (see MINIMUM Expansion and Adhesive Anchors REQUIREMENTS). Lag screws may be used only when Use approved expansion or adhesive anchors when the field conditions conform to those shown in Figure attaching a ledger board to a concrete or solid masonry 14. See Figure 20 for lag screw length and shank wall as shown in Figure 15. Expansion and adhesive requirements. All lag screws shall be installed with anchor bolts shall have a diameter of'A". Minimum washers. spacing and embedment length shall be per the Figure 20. Lag Screw Requirements. lag screws must be hot- dipped galvanized or ( ¢ stainless steel only screw must penetrate , 1-1 /2"shank length must extend through beyond band board a minimum of 1/2" (no threads) existing band board L11 ` Lag screw installation requirements: Each lag screw SCREWS WITH A HAMMER. Use soap or a wood- shall have pilot holes drilled as follows: 1)Drill a %" compatible lubricant as required to facilitate tightening. diameter hole in the ledger board,2)Drill a 5/16" Each lag screw shall be thoroughly tightened(snug but diameter hole into the band board of the house. DO NOT not over-tightened to avoid wood damage). DRILL A '/2" DIAMETER HOLE INTO THE BAND JOIST. The threaded portion of the lag screw shall be inserted into the pilot hole by turning. DO NOT DRIVE LAG American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 17 , NON-LEDGER DECKS-FOR RESISTING FOOTINGS SHALL BE PLACED AT THE SAME _ VERTICAL LOADS ELEVATION AS THE HOUSE FOOTING IF Non-ledger decks use the house for resisting lateral loads LOCATED CLOSER THAN 5'-0" TO A HOUSE but do not utilize the exterior wall of the house to WALL(see Figure 2 and Figure 12). For houses with support vertical loads (see Figure 21). Rather than basements, a cylindrical footing(caisson) is supporting the deck on a ledger, an additional beam with recommended to minimize required excavation at the posts is provided at or within the lesser of Lo or L/4 of basement wall. Beam size is determined by Table 3. the house. THE ASSOCIATED DECK POST Non-ledger decks shall be attached to the house per Table 5 and Figures 22 or 23 for lateral loads. Figure 21. Non-Ledger Deck - For Resisting Vertical Loads. blocking between overhanging joists rim joist at beam bearing rim t• �`���/V joist 4overhang 41 existing house !JOiStfoundation wall �� r posts same II beam, eck footings must be at VII as \/ joists existing house footing install diagonals if located closer than } per Figure 10 \ 5'-0"to house wall Note:Tension device not shown. See provision for deck lateral forces. DECK LATERAL LOADS For non-ledger decks,blocking or framing angles can be Attachment to House: Decks shall be positively used in lieu of joist hangers and shall be provided on anchored to the primary structure [R507.1]. The lateral each side of each joist. Blocking shall be installed with connection required shall be permitted to be in 5-10d threaded nails into the rim joist or the framing accordance with Figure 22 or 23 for ledger and non- angle shall have a lateral capacity of 600 lb. Flashing ledger decks. Hold-down tension devices shall be over the rim joist is required and must be installed in provided in not less than two locations within two feet of accordance with the flashing provisions in the LEDGER the edge of the deck, and shall have an allowable stress ATTACHMENT REQUIREMENTS. design capacity of not less than 1,500 lb [R507.2.4]. The wall must be sheathed with minimum 3/8" wood structural panel sheathing. Use lag screws or through- bolts when fastening to a band joist;use expansion - anchors or epoxy anchors when fastening to concrete or masonry. DO NOT ATTACH TO BRICK VENEERS. VERIFY THIS CONDITION IN THE FIELD PRIOR . TO UTILIZING THIS METHOD. Fasteners shall penetrate beyond the house band board and be installed per Table 5. American Wood Council 18 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE • Figure 22. Lateral Load Device with Floor Joists Parallel to Deck Joists. l: floor sheathing nailing at I fasteners per Table 5 6" maximum on center to joist with hold down hold-down or similar tension device T T T T .�irr�r.i�rrr—rrri�irr��.rr�rrr—•I11►�.��..I►��.�.. �/�. �111►I Iriit}l�ii� r ;i III ►�;j� threaded rod, ma be ►�I sloped up to 1:12 away from the house ��! deck joist solid sawn r`,I VWV_ floor joist beam&post for non-ledger joist hanger ,,•, decks (for non-ledger decks, blocking or framing angle) ---.-- 36"min. ___T\.' attach to Hoist E fasteners per Table 5 w/a minimum of(19)8d nails i hold-down or similar tension device }*• +� deck joist • " ` III ��€ L threaded rod, may be U i� sloped upto1:12 minimum 2x6 x 36" @ away from the house ��� attached to joist web w/ (16) 10d nails and clinch Hoist I 11 beam&post L joist hanger I `\, for non-ledger (for non-ledger decks, g decks blocking or framing angle) Figure 23. Lateral Load Device with Floor Joists Perpendicular to Deck Joists. threaded rod, may be sloped up to 1:12 6 ft.min. away from the house extent of blocking ` attach blocking to deck w/ fasteners per Table 5 10d nails at 4"o.c.staggered \ hold-down or similar \i tension device { r ,f r_ deck joist 1 n I II I minimum 1 2'thick floor joist blocking.Blocks must (I-joist or fill bay and fit snugly solid joist) joist hanger — beam&post (for non-ledger deck, for non-ledger decks blocking, or framing angle) ,a American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 19 GUARD REQUIREMENTS construction when approved by the authority having All decks greater than 30" above grade are required to jurisdiction. • have a guard [R312.1] -one example is shown in Figure 24. Other methods and materials may be used for guard Figure 24. Example Guard Detail. 2x2 baluster,typical 4x4 post,typical 2x6 or 5/4 board rail cap:attach to guard post with DO NOT NOTCH ['"'i 6'-0"maximum spacing 1(3)#12 by 3"long screws or(3)16d threaded nails with 0.148"nominal diameter minimum 2x4 top and bottom; attach to guard post with (2)8d threaded nails or -m a �_�■m■_.�_ti�� VI'P long wnoodi c screwsfacs>2--%" 1111:10 :. -+— minimum nominal 2x8 rim or outside joist (2)1/2"diameter openings shall not allow attach balusters at top and bottom through-bolts the passage of a 4" with(1)#8 wood screw or(2)8d and washers diameter sphere post-frame threaded nails with 0.135"nominal diameter GUARD POST ATTACHMENTS FOR REQUIRED Figure 25. Guard posts for required guards that run GUARDS perpendicular to the deck joists shall be attached to the Deck guard posts for required guards shall be a rim joist in accordance with Figure 26. Only hold-down minimum 4x4 (nominal)with an adjusted bending anchor models meeting these minimum requirements design value not less than 1,100 psi. Joists and rim joists shall be used. Hold-down anchors shall have a minimum to which guard posts are attached shall be a minimum of allowable tension load of 1,800 pounds for a 36" 2x8 (nominal). maximum guard height and be installed in accordance with the manufacturer's instructions. Guard posts for required guards which run parallel to the deck joists shall be attached to the outside joist per Figure 25. Guard Post to Outside-Joist Example. ►=•r see FIGURE 24 for guard *guard posts can be installed as ►i component attachment shown in Figure 26(between joists) guard posts may be requirements if blocking is installed as shown below located on either side within 12"of each side of the post of the outside joist at first interior bay, provide 2x blocking at guard posts guard post with hold-down anchors;attach blocking with 10d threaded nails top and bottom, each side (2)1/2"dia.through- ►+ outside-joist • bolts and washers - min. 2x8(nom.) motionf Alternate attachment of hold-down E 2"min. T. coo anchors to framing members 2-1/2"min.and 5"max. ,!. possible per manufacturer's 2"min. A Ti instructions. outside joist SECTION guard post* PLAN VIEW min. 2x8(nom.) American Wood Council 20 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE Figure 26. Guard Post to Rim Joist Example. Alternate attachment of hold-down anchors to framing members are possible per manufacturer's instructions. see FIGURE 24 for guard �' hold-down anchor ►,t component attachment requirements joists .41; guard post guard post align guard ■ 7;7— post at joist rim joist i locations min. 2x8 (nom.) hold-down anchor �. rim joist joist rim joists min. 2x8 (nom.) �-!7 EMImin. 2x8 (nom.) minimum (2)1/2" 0 o a! '_ 2"min. hold-down anchor diameter through- ���m 2-1/2" min. and 5"max. bolts and washers ' = 2" min. at joist location between joists SECTION PLAN VIEWS STAIR REQUIREMENTS Figure 27. Tread and Riser Detail. Stairs, stair stringers, and stair guards shall meet the requirements shown in Figure 27 through Figure 34 and riser may be open,but Table 6 except where amended by the local jurisdiction. shall not allow the All stringers shall be a minimum of 2x 12. Stair stringers passage of a 4^diameter 10"minimum p shall not span more than the dimensions shown in Figure , , - 1 i 28. If the stringer span exceeds these dimensions,then a tread width ) 4x4 post may be provided to support the stringer and 7-3/4°maximum riser;height shall shorten its span length. The 4x4 post shall be notched not deviate from risers:1x material,minimum and bolted to the stringer with(2) '/2" diameter through- one another by bolts with washers per Figure 8A. The post shall be more than 3/8" centered on a 12" diameter or 10" square, 6" thick treads:see Figure 29 and Table 6 footing. The footing shall be constructed as shown in 3/4•-1-1/4"nosing;nosing shall not deviate from one Figure 34 and attached to the post as shown in Figure 12. another by more than 3/8" An intermediate landing may also be provided to shorten the stringer span(see provisions below). If the total vertical height of a stairway exceeds 12'-0",then an intermediate landing shall be required.All intermediate stair landings must be designed and constructed as a non-ledger deck using the details in this document. Stairs shall be a minimum of 36" in width as shown in Figure 33 [R311.7]. If only cut stringers are used, a minimum of three are required. For stairs greater than 36" in width, a combination of cut and solid stringers can be used,but shall be placed at a maximum spacing of 18" on center(see Figure 29). The width of each landing shall not be less than the width of the stairway served. Every rectangular landing shall have a minimum dimension of 36" measured in the direction of travel and no less than the width of the stairway served [R311.7]. American Wood Council ' PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 21 . Figure 28. Stair Stringer Requirements. Figure 29. Tread Connection Requirements. Attachment per tread at each stringer or ledger: 2x_or 5/4 treads-(2)8d threaded nails or(2)#8 screws z2-1/2"long; 3x_treads-(2)16d threaded nails or(2)#8 screws a3-1/2"long stringer treads:2x_or 5/4 board treads:see Table 6 l t �, 18"`max 1 18"max �' l 3, 36"max i 1 �? 2x4 ledgers,each side,full depth of stringers tread;attach with(4)10d threaded ------- nails or(4)#8 wood screws a3"long max.span=6'-0" CUT STRINGER SOLID STRINGER , 3 CUT STRINGER J max.span=13'-3" SOLID STRINGER Figure 30. Stair Guard Requirements. Figure 31. Stair Stringer Attachment Detail. 6'-0"maximum rim joist or—\ between posts outside joist stair guard is required for imi. —eimm stairs with a total rise of � ! 30"or more;see GUARS? REQUIREMENTS for more information ,qi � i I sloped joist hanger, . Oil ll minimum vertical capacity of 625 lbs; see JOIST HANGERS :0 8 ' for more requirements stair guard height: 34"min. measured ATTACHMENT WITH HANGERS �` from nosing of step i sommium iip Openings for required guards on the Triangular opening shall Table 6. Minimum Tread Size for Cut and Solid sides of stair treads shall not allow not permit the passage Stringers.' a sphere 4-3/8"to pass through. of a 6"diameter sphere. Cut Solid Species Stringer Stringer Southern Pine 2x4 or 5/4 2x8 Douglas Fir Larch, Hem-Fir, SPF2 2x4 or 5/4 2x8 or 3x4 Redwood, Western Cedars, Ponderosa Pine,3 Red Pine3 2x4 or 5/4 2x10 or 3x4 1.Assumes 300 lb concentrated load, L/288 deflection limit,No.2 stress grade,and wet service conditions. 2. Incising assumed for Douglas Fir-Larch, Hem-Fir,and Spruce- Pine-Fir. 3. Design values based on northern species with no incising assumed. American Wood Council 22 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE • STAIR HANDRAIL REQUIREMENTS STAIR FOOTING REQUIREMENTS [R4031 _ All stairs with 4 or more risers shall have a handrail on Where the stairway meets grade, attach the stringers to - at least one side(see Figure 32A) [R311.7.8].The the stair guard posts as shown in Figure 34. Posts shall handrail height measured vertically from the sloped bear on footings. All footings shall bear on solid ground plane adjoining the tread nosing shall be not less than 34 and shall be placed at least 12 inches below the inches and not more than 38 inches (see Figure 30) undisturbed ground surface or below the frost line, [R311.7.8.1]. Handrails shall be graspable and shall be whichever is deeper(see Figure 34). Stringers shall bear composed of decay-resistant and/or corrosion resistant on a 2x4 bearing block attached to the post as shown. material. Handrails shall be Type I, Type II, or provide Stringers shall not bear on new or existing concrete pads equivalent graspability (see Figure 32B). Type I shall or patios that are not founded below this depth. When have a perimeter dimension of at least 4" and not greater guards are not required(see GUARD than 6-'/4". Type II rails with a perimeter greater than REQUIREMENTS),posts may terminate below the 6-'/4" shall provide a graspable finger recess area on both bottom tread elevation. Bolts are only required if a guard sides of the profile [R311.7.8.3]. All shapes shall have a post is required. smooth surface with no sharp corners. Handrails shall STAIR LIGHTING REQUIREMENTS [R303.71 run continuously from a point directly over the lowest riser to a point directly over the highest riser and shall Stairways shall have a light source located at the top return to the guard at each end(see Figure 33). Handrails landing such that all stairs and landings are illuminated. may be interrupted by guard posts at a turn in the stair The light switch shall be operated from inside the house. [R311.7.8.2]. However,motion detected or timed switches are acceptable. Figure 32A. Handrail Mounting Examples. Figure 33. Miscellaneous Stair Requirements. - - - - L G. ems= 41) ZS Fasten handrailsm .. per manufacturer recommendations t o 1;"min. '0 c�t> ?C 1,t min., — — r c a w -- 2Ai1C �- 1 t,min. 111 — handrail (a, L handrail shall 2x blocking return at each 1z min. 17 min, end 34"-38"to nosing of stairs.typical 36"min.stair width wall _.� -•...- ....corrosion-resistant I 1 t X -+--guard handrail hardware I i post I 1 I I I I t 1 r-1.-1-1 j_j-1 MOUNTED TO GUARD MOUNTED TO WALL 1 1 t X t X t J l J Figure 32B. Handrail Grip Size. Figure 34. Stair Footing Detail. 14"-2;" cut post at bottom tread (2)/:"diameter through-bolts elevation when no stair with washers required only 1n guard is required if guard is required;otherwise 14 -2" use(2)#8 wood screws a3--'/z" 2r max. c ` • long or(2)16d threaded nails P1 + 1B" ^°' E0 u r I Attach 2x4 bearing block using min. stair It/ (8)#8 wood screws a3-/w"long stringer 1 die or(8)16d threaded nails iiilr— 4x4 —; NONCIRCULAR CIRCULAR RECESSED post NI i .E [R311.7.7.3 Type I] ER311.7.7.3 Type II] 6"isso E Perimeter:4"-64" Perimeter:>64" minimum �1� frost depth 10"x10"square or 12"dia.footing American Wood Council 1 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE 23 FRAMING AT CHIMNEY OR BAY WINDOW shown in Figure 1B. Joist hangers shall each have a • All members at a chimney or bay window shall be minimum vertical capacity in accordance with Table 7. Bolts, screws, or lag screws used to attach the hanger to framed in accordance with Figure 35. Headers may span a maximum of 6'-0". When a chimney or bay window is the ledger shall fully extend through the ledger into the wider than 6'-0", one or more 6x6 posts may be added to 2-inch nominal lumber band joist(1-'/2" actual) or LVL reduce header spans to less than 6'-0". In such cases,the rim joist. Otherwise a non-ledger deck is required. post footing must meet the requirements in the FOOTINGS section. Headers shall be located no more Table 7. Trimmer Joist Hanger Vertical Capacity. than 3'-0" from the end of the trimmer joist. Joist Size Minimum Capacity, lbs Triple trimmer joists are required on each side of the 2x6 870 header if joist spacing is 12" or 16" o.c. or if the trimmer joist span exceeds 8'-6"; otherwise, double trimmer joists 2x8 1155 are permitted. Trimmer joists may bear on the beam and 2x10 1420 extend past the beam centerline up to the lesser of Lo or L/4 as shown in Figures lA and 2,or the trimmer joist 2x12 1575 may attach to the side of the beam with joist hangers as Figure 35. Detail for Framing Around a Chimney or Bay Window. a =3'-0"maximum triple joist 6'-0" maximum hanger,typical decking may _. ,-- "' {Table 7) extend 6"maximum r r / �sr - r chimney bamwnndow or bayBolts,screws, or lag Y / windw °> /i///////////�,f/ ledge screws shall fully board `}1 r ir ir \ 1 cti IA {' extend into band joist or rim board triple trimmer double joist '4-double header (2)%'11, "diameter through-bolt joist each side* hanger,typical or lag screws at ledger* I *Trimmer joist may be double if joists are spaced *See Figure 19 for fastener spacing, 24"o.c.or if trimmer length is 8"-6"or less edge,and end distances PLAN VIEW SECTION American Wood Council ,arrr► -,. 24 PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE • REFERENCES 2015 International Residential Code(IRC), International ASTM Standard B 695-04, Standard Specification for Code Council(ICC),Washington, DC,2015. Coatings of Zinc Mechanically Deposited on Iron and Steel, ASTM,West Conshohocken,PA 2016. ANSI/ASME Standard B18.2.1-2010, Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, ASTM F 1667-17, Standard Specification for Driven Hex Flange, Lobed Head, and Lag Screws (Inch Series), Fasteners:Nails, Spikes, and Staples,ASTM, West American Society of Mechanical Engineers,New York, Conshohocken, PA 2017. NY, 2010. Attachment of Residential Deck Ledger to Metal Plate ANSI/ASME Standard B18.6.1-1981 (Reaffirmed 1997), Connected Wood Truss Floor System, Structural Wood Screws (Inch Series), American Society of Building Components Association(SBCA), Mechanical Engineers,New York,NY, 1982. www.sbcindustry.com,2015. ASTMA 123-17, Specification for Zinc (Hot Dip AWPA Book of Standards,American Wood Protection Galvanized) Coatings on Iron and Steel Products, Association,Birmingham,AL,2017. ASTM, West Conshohocken,PA 2017. ASTM Standard A 153-16a, Standard Specification for Policy for Evaluation of Recommended Spans for Span Zinc Coating (Hot-Dip) on Iron and Steel Hardware, Rated Decking Products,American Lumber Standard ASTM,West Conshohocken, PA 2016. Committee, Germantown, MD 2004. ASTMA 653-17, Standard Specification for Steel Sheet, Zinc-Coated(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process, ASTM,West Conshohocken, PA 2017. -�Y 4 ` ►�\_ o� AMERICAN ...�. WOOD En r�INTERNATIONAL COUNCIL 1?4Z �jRcir�ti�► CODE COUNCIL It is intended that this document be used in conjunction with competent design, accurate fabrication, and adequate supervision of construction. While every effort has been made to insure the accuracy of the information presented, the American Wood Council and its members do not assume responsibility for errors or omissions in the document, nor for designs, plans, or construction prepared from it. Those using this document assume all liability arising from its use. Copyright©2007, 2009, 2010, 2014, 2015, 2018 American Wood Council 04-18 American Wood Council Prescriptive Residential Wood Deck Construction Guide-Appendix Al F: Litptance Appendix A to Prescriptive Residential Wood Deck Construction Guide DCA 6 SAFETY GLAZING REQUIREMENTS: IRC Exceptions to this requirement include: R308.4 states that safety glazing in window glass is required when the existing house wall acts as a barrier to - When a protective bar is installed on the accessible adjacent stairs, landings, and areas at the top and bottom side(s)of the glazing 36"f 2"above the deck of stairs. If a window or portion thereof falls within the surface. The bar shall be capable of withstanding a area shown in Figure Al, glass panes within that area horizontal load of 50 plf without contacting the glass should be safety glazed. Safety glazing should reduce and be a minimum of 1-1/4" in height. injury due to accidental impact when ascending or - The side of a stairway, landing,or ramp has a descending stairs. Application of safety glazing film to guardrail or handrail, including balusters or in-fill glass that was not originally treated is acceptable to meet panels,complying with the provisions of Sections this requirement. R311.7.8 and R312 and the plane of the glass is more than 18" from the railing. - When a solid wall or panel extends from the plane of the adjacent walking surface to 34" -36" above the floor and the construction at the top of that wall or panel is capable of withstanding the same horizontal load as the protective bar. H 36 0-I glass in windows within �•;•;•;•;•j.;.;.;.;p'•;;•;i this area adjacent stairs iiii•::❖:O❖i:•ii:• must be safety glazed 44s ..444444444VT .�� ........................................... ramov mgAmk ........................................... ........................................... ••.•.o•.o•.o•.•❖••o••o❖.00❖.S.•❖.•.•.o❖.•.•.•.•.o•.•.•.•.•.•.• ........................................... 00000•.•.••❖.•.0000•.0000.•000n •0000•• •o••000•o•o• ••000•o. •o•.•.•.•.•.o•.•.00000000•.•.0000.•--- ......................I 60" Figure Al. Safety glazing requirements. American Wood Council 4* 'ea fii/a/MHOOMONSWithk, Prescriptive Residential Wood Deck Construction Guide - Appendix B1 Figure Bl.Examples of Tributary Areas . Design for ■ • Code Acceptance 6 • l Appendix B to $144.4,.•�;.;.:.,:;/ Prescriptive Residential • ;0. +4it xt Wood Deck Construction Guide , ' •• :•X:••❖•4;:• ••*:•.•o❖:•,•• Di• ,/ S.A.:$1,002441 41 This Appendix to DCA 6-Prescriptive Residential / p % >.•.:•;.o•.,•o a:ilt, i Wood Deck Construction Guide has been requested by /AV•o a•.❖,„❖lo. : %i builders,building officials,and others,to provide an let----ilk-----la.----?a t.-- alternative to the assumptions of Table 4 Post Height for so — 6x6 and Footings Sizes for all Posts.DCA 6 is written to • Post be as simple and easy to use as possible;however,this u Comer Tributary Area means that conservative assumptions often have to be ,4 Center Tributary Area made. This is especially true for Table 4,which assumes Joist Length,JL full full cantilevers on both the joist and the beam. If The joist length is defined differently for this appendix cantilevers are not present,the load will be less than than the main provisions of DCA 6. The joist length is assumed in Table 4, and the footing size will often not the design span of the joist,but is from the ledger decrease and allowable post height will often increase. face to either the center point of the beam, if there is an This Appendix is an aid to calculating the loads on posts overhang,or to the outside face of the rimboard if there and footings based on the actual deck configuration. is not an overhang. See Figure B2. Tributary Area Joist Overhang Length,Jo Since uniform loading is prescriptively set for DCA 6, The length of the joist overhang is measure from the only the area the post or footing is supporting needs to outside edge of the deck to the centerline of the beam. be determined. This is called the tributary area and is See Figure B2. If no overhang exists, zero is entered into shown in Figure Bl.Tributary area of a center or corner equation B-1 or B-2 for Jo. post can be found from Figure B 1 or by using the following formulas: Figure B2.Joist Length and Overhang existing wall ACeaterPost=(1JL+J0)(BL) Eq. B-1 joist f; 2 ►. IX1►7s►c�►_.r►�.r►:r►._..���i►-4 A =(1J +J )(1B +B )E B-2 rim joist CornerPost 2 I. O 2 L O q' MIIIIIIIIIIIIIMW I+ 'A Joist anger Where: ledger board / . A is tributary area(ft2) JL is length of joist(ft) Jo is length of joist overhang(ft) BL is the length of the beam span(ft) post Bo is the length of the beam overhang(ft) t;= Lo JL. fi American Wood Council B2 Prescriptive Residential Wood Deck Construction Guide-Appendix • Beam Span Length,BL Figure B3. Beam Span and Overhang Length The beam span is measured from either centerline of joists • post to centerline of post, if there are overhangs, or to the outside edges of the deck, if there are no overhangs. For posts or footings being considered with two unequal, 1' adjacent beam spans, the greater span shall be used. See Figure B3. beam Beam Overhang Length,Bo post The length of the beam overhang is measured from the outside edge of the deck to the centerline of the nearest post. See Figure B3. If a center post or footing is being so B Bo considered or no overhang exists,zero is entered into the equation B-1 or B-2 for Bo. Post and Footings Size As an alternative to Table 4 of DCA 6, the post height and footing size may be in accordance with Table B l through B3. American Wood Council Prescriptive Residential Wood Deck Construction Guide-Appendix B3 Table B1. Post Heights Based" on Tributary Area for Corner Posts. 6x6 Post Height(ft.) 4x4 Post Height(ft.) Cl) csi,i Q — LL ii N , o E c b i.L N a) 78 CI U) O � V! 2 a) Z'$ E c� c O c a� € c o c IS a) CO CO E L -O L c N E L -0 L nv L ZJ m a) a) a) Q = J a) a) a) a) O - = 0 I n f -0 _ = o I w X 73 -0 H 0 0 m co 0 0 a) Ca, d d W 10 14 14 14 14 14 9 7 7 11 8 20 14 14 14 14 14 6 4 5 7 5 30 14 14 14 14 14 5 3 4 6 4 40 14 14 14 14 14 4 3 3 5 3 50 14 14 14 14 14 4 2 3 4 3 60 14 14 14 14 14 3 2 2 4 2 70 14 14 14 14 13 3 2 2 3 2 80 14 14 13 14 12 2 2 2 3 2 90 14 14 12 14 10 2 2 2 2 2 100 14 14 11 13 9 2 2 2 2 2 110 14 13 10 12 7 2 2 2 2 2 120 13 12 10 12 6 2 2 2 2 2 130 13 11 9 11 4 2 2 2 2 2 140 12 11 8 10 2 2 2 2 2 2 150 11 10 7 10 2 2 2 2 2 2 160 11 9 6 9 2 2 2 2 2 2 170 10 9 5 9 NP 2 2 2 2 2 180 10 8 3 9 NP 2 2 2 2 2 190 10 7 2 8 NP 2 2 2 2 2 200 8 7 2 8 NP 2 2 2 2 2 210 8 6 2 7 NP 2 2 2 2 2 220 7 5 2 7 NP 2 2 2 2 2 230 6 4 2 7 NP 2 2 2 2 2 240 6 2 2 6 NP 2 2 NP 2 2 250 5 2 2 6 NP 2 2 NP NP NP 1.Assumes No 2. Stress grade and wet service conditions. 2. Incising assumed for Douglas fir-larch, hem-fir, and spruce-pine-fir. 3. Some post heights for 4x4 post sizes show a greater load carrying capacity than 6x6 post sizes since different ASTM Standards are used to develop design values for visually graded dimension lumber vs. visually graded timbers. American Wood Council 84 Prescriptive Residential Wood Deck Construction Guide-Appendix Table B2. Post Heights Based" on Tributary Area for Center Posts. 6x6 Post Height(ft.) 4x4 Post Height(ft.) L N , L N as c IL Q a LL N L N o a co a U- N L a co CO c CO E L "Q C L II c E L OL C o f I ry -o -0 = o f a) a) a) � a 10 14 14 14 14 14 14 14 14 14 14 20 14 14 14 14 14 14 14 14 14 14 30 14 14 14 14 14 14 14 13 13 14 40 14 14 14 14 14 13 14 11 11 12 50 14 14 14 14 14 11 12 10 10 10 60 14 14 14 14 14 10 11 10 9 10 70 14 14 14 14 14 9 10 9 8 9 80 14 14 14 14 14 9 9 8 7 8 90 14 14 14 14 14 8 9 7 7 7 100 14 14 14 14 14 8 8 7 7 7 110 14 14 14 14 14 7 8 6 6 6 120 14 14 14 14 14 7 7 6 6 6 130 14 14 14 14 13 6 7 5 6 6 140 14 14 13 14 11 6 7 5 5 5 150 14 14 13 14 10 6 6 5 5 5 160 14 14 12 13 8 6 6 5 5 5 170 14 14 11 13 6 5 6 4 4 5 180 14 14 11 12 NP 5 6 4 4 4 190 13 13 11 12 NP 5 5 4 4 4 200 13 13 10 11 NP 4 5 3 4 4 1 210 12 12 8 11 NP 4 5 3 3 3 220 12 11 8 10 NP 4 5 2 3 3 230 11 11 7 10 NP 4 4 2 3 2 240 10 10 6 10 NP 3 4 NP 2 2 250 10 10 5 9 NP 3 4 NP 1 NP 1. Assumes No 2. Stress grade and wet service conditions. 2. Incising assumed for Douglas fir-larch, hem-fir, and spruce-pine-fir. 3. Some post heights for 4x4 post sizes show a greater load carrying capacity than 6x6 post sizes since different ASTM Standards are used to develop design values for visually graded dimension lumber vs.visually graded timbers. 4. Tributary area shall be multiplied by 1.25 at center posts with beams not spliced (continuous). I American Wood Council Prescriptive Residential Wood Deck Construction Guide-Appendix B5 Table B3. Footing Sizes' Based on Tributary Area for Various Soil Capacities. Soil Bearing Capacity 1500 psf 2000 psf 2500 psf 3000 psf c c C c • c • O O 0 O 0) O O Cr) O L O C <A O i O C fn O i O C fA 0 " O O fn LL 4) LL "r LL a) LL C "... U) LL a) LL C "= 4) LL 2 LL . +� a) :T3 c U) O C - 4) 2-) p C - N 2-) v O C -0 (I) 228 O E ca LL U E c, LL U E N LL V c E co 0 co LL V 10 8 7 6 7 7 6 7 6 6 6 5 6 20 12 10 6 10 9 6 9 8 6 8 7 6 30 14 13 6 12 11 6 11 10 6 10 9 6 40 16 15 6 14 13 6 13 11 6 12 10 6 50 18 16 7 16 14 6 14 13 6 13 12 6 60 20 18 8 17 15 6 16 14 6 14 13 6 70 22 19 9 19 17 7 17 15 6 15 14 6 80 23 21 9 20 18 8 18 16 7 16 15 6 90 25 22 10 21 19 8 19 17 7 17 15 6 100 26 23 11 23 20 9 20 18 8 18 16 7 110 28 25 12 24 21 10 21 19 8 19 17 7 120 29 26 12 25 22 10 22 19 9 20 18 8 130 30 27 13 26 23 11 23 20 9 21 18 8 140 31 28 13 27 24 11 24 21 10 22 19 9 150 33 29 14 28 25 12 25 22 10 22 20 9 160 34 30 15 29 25 12 25 23 10 23 20 9 170 35 31 15 30 26 13 26 23 11 24 21 10 180 36 32 16 30 27 13 27 24 11 24 22 10 190 37 33 16 31 28 13 28 25 12 25 22 10 200 38 34 17 32 29 14 28 25 12 26 23 11 210 39 35 17 33 29 14 29 26 12 26 23 11 220 40 35 18 34 30 15 30 26 13 27 24 11 230 41 36 18 35 31 15 31 27 13 28 25 12 240 42 37 19 35 31 15 31 28 13 28 25 12 250 43 38 19 36 32 16 32 28 14 29 26 12 1. Assumes 40 psf live load, 10 psf dead load, 150 pcf concrete and 2,500 psi compressive strength of concrete. Coordinate footing thickness with post base and anchor requirements. 2. Tributary area shall be multiplied by 1.25 at center posts with beams not spliced (continuous). American Wood Council Prescriptive Residential Wood Deck Construction Guide-Commentary Cl Commentary to Prescriptive Residential 111 Wood Deck Construction Guide Design for DCA 6 Code Acceptance 6 U Foreword debr, ng This Commentary to DCA 6—Prescriptive Residential t�9ef Wood Deck Construction Guide has been requested by b'° 0%--t, I III fasteners along house builders,building officials,and others,to provide 111 Boor contraucuop background information and example calculations for �� .� ► various sections and tables of DCA 6. ,' guard post ledger board etlaNment i /'� € attachment to ,.. existing house The DCA 6 Commentary follows the same organization ,�, as DCA 6. Discussion of a particular provision in DCA 6 mil Mot I iotS1 is found in the DCA 6 Commentary by locating the same l/00° ^ x ` post-lo•beam conenarmn {flush light beannW section or subsection found in DCA 6.Not every section foong- Est-fo-baem pas+ cennechon of DCA 6 has a corresponding commentary section. The DCA 6 Commentary provides background information intended to give the reader an understanding of the data and/or experience upon which the provision is based. Background One or more examples of the calculation procedures In August 2006,AWC,then part of the American Forest used to produce several of the tables are given to &Paper Association, formed an ad-hoc task group to address prescriptive provisions for residential wood deck illustrate the scope of conditions covered by the table. construction. Representatives of the wood products The provisions of DCA 6 come primarily from the industry,home builders, connector manufacturers, International Code Council's(ICC)International building officials, and truss industry were represented on Residential Code(IRC). In developing the DCA 6 the task group. Commentary, data available from laboratory tests and experience with structures in-service was analyzed and The task group was assigned to review existing evaluated for the purpose of providing a consistent information to determine if there was something on explanation. It is intended that this document be used in which to build. One resource reviewed was a document conjunction with competent design, accurate fabrication, developed by the Fairfax County,Virginia Department and adequate supervision of construction. Therefore,the of Public Works and Environmental Services titled American Wood Council(AWC)does not assume any Typical Deck Details. With Fairfax County's permission, responsibility for errors or omissions in the DCA 6 this became the basis for DCA 6. Commentary,nor for designs or plans prepared from it. Since Fairfax County's Typical Deck Details was Inquiries, comments, and suggestions from readers of developed for a specific geographic location,DCA 6 was this document are invited. expanded to apply on a national basis(e.g. addition of western lumber species). The first version of DCA 6 was American Wood Council posted to the AWC website in October 2007. At the end of 2013 and into 2014,the task group was formed again to update DCA 6 to be in compliance with the 2012 IRC.DCA6-12 was posted on the AWC website in June 2014.DCA6 was updated based on the 2015 IRC and was posted in April 2018. Copyright© 2018 American Wood Council C2 Prescriptive Residential Wood Deck Construction Guide-Commentary Basis intent of the provisions of this code, and that the As stated in the boxed text on the cover of DCA 6, material,method or work offered is, for the purpose provisions and details are based on the International intended,at least the equivalent of that prescribed in this Code Council's International Residential Code. The code."While AWC develops design tools and guidelines original version of DCA 6 was based on the 2006 IRC. for wood construction,it is recognized that decks are The current version of DCA 6 is based on the 2015 IRC. built with materials other than wood. Many of these materials undergo scrutiny through a code evaluation Alternative Methods and Materials process such as that promulgated by ICC's Evaluation A key point for users is the statement: "This document is Services. Typically,the result is an Evaluation Service not intended to preclude the use of alternative methods Report(ESR)for the product. The building official is and materials."Further,IRC R104.11 states: "An usually the authority having jurisdiction and makes the alternative material, design or method of construction final decision regarding all construction methods and shall be approved where the building official finds that materials. the proposed design is satisfactory and complies with the MINIMUM REQUIREMENTS and LIMITATIONS include helical(spiral) and annular(ring-shank)nails as 1. This document applies to single level residential wood defined in ASTMF 547. Including the common terms decks only.Multiple level decks will likely have stairs "spiral"and"ring-shank"is important to ensure that create additional concentrated loads that are not availability from lumber yards. Reference design values considered in the joist and beam span tables for DCA 6. for post-frame ring shank nails in accordance with ASTM Non-residential decks or balconies typically require F1667 are provided in the 2015 National Design design by a licensed professional. All decks prescribed Specification®(NDS4)for Wood Construction. in DCA 6 use the primary structure to resist lateral forces per Section R507.2.4 of the IRC. 6.NDS Chapter 11 contains spacing,end,and edge distance requirements for various fasteners,including 2. This ratio is limited to 1:1, similar to open-front bolts and lag screws. structures defined in Special Design Provisions for Wind and Seismic(SDPWS).Decks covered in this document 7. When subjected to standardized laboratory tests that are assumed to be diaphragms that cantilever from the accelerate the corrosion process,metal connectors and house and are limited to a deck length-to-width ratio of fasteners exposed to the chemicals used in certain 1:1. Larger aspect ratios may be permitted where preservative treatments exhibit high rates of corrosion. calculations show that larger diaphragm deflections can Users should rigorously apply recommendations of the be tolerated. See Deck Framing Plan. chemical manufacturers and the treating industry—to use corrosion resistant fasteners and connectors or zinc 3.DCA 6 provides 6x6 nominal posts as the primary coated(galvanized) fasteners and connectors with corrosion protection at least equivalent to that of hot-dip prescriptive solution with the alternative to substitute 8x8 posts. In some instances,this commentary provides galvanized products.Additional information is available a 4x4 nominal post alternative. See commentary from various sources including: m regarding Table 4. http://awc.org/faqs/general/where-can-i-find- information-about-corrosion-of-fasteners 4. Table 1 does not provide an exhaustive list of preservative treatments for ground contact lumber. The FEMA TB8-96, Technical Bulletin 8, Corrosion American Wood Protection Association(AWPA) Protection of Metal Connectors in Coastal Areas, recommends that stainless steel fasteners be used in promulgates voluntary wood preservation standards. AWPA Standards are developed by its technical areas exposed to salt water. committees under an ANSI accredited consensus-based process.Note also that many preservative treatments 8. Concentrated loads, such as those created by hot tubs, undergo scrutiny through a code evaluation process such stairs,and planters, are beyond the scope of DCA 6. as that promulgated by ICC's Evaluation Services. Typically,the result is an Evaluation Service Report 9. Structural members and connections shown in DCA 6 (ESR) for the product. have been sized based primarily on a uniformly distributed floor live load of 40 psf and a dead load of 10 5. Smooth shank nails are prone to"backing out"of psf(table footnotes specify where other point loads have wood due to moisture cycling. Deformed-shank nails been considered). If a deck is not prone to sliding or American Wood Council - _ ._ Prescriptive Residential Wood Deck Construction Guide-Commentary C3 drifting snow,the criteria in DCA 6 can be wall or floor assembly of wood-frame construction." t conservatively applied to a deck with a uniformly Aluminum flashing should not be used if it will be in . distributed snow load of 40 psf and a 10 psf dead load. contact with treated lumber. Lumber treated with certain preservatives contain copper and will corrode aluminum 10. Section R507.1 of the IRC states that decks shall be flashing as well as ferrous metals. F designed to resist lateral loads and that the design is permitted to be per IRC Section 507.2.4. The IRC 12.IRC R110.1 Use and occupancy states: "A building currently does not state the design lateral loads for or structure shall not be used or occupied...until the decks,but it does provide an approved design,which building official has issued a certificate of occupancy..." DCA 6 incorporates. 13. See Commentary for Alternative Methods and 11.IRC R703.4(5)requires attachment of flashing Materials. "...Where exterior porches, decks,or stairs attach to a DECKING REQUIREMENTS The American Lumber Standard Committee(ALSC) Load Conditions—Allowable span analysis includes the Policy for Evaluation of Recommended Spans for Span following two load conditions with load applied on one Rated Decking Products(ALSC Decking Policy) span of a two-span continuous beam: provides a uniform method for assessing span-rated a. Uniform Load—the calculated maximum decking products which are produced from many allowable fiber stress in bending derived from ASTM different species of wood,and graded under several D2555 and D245, or the In-grade test procedures of different grading standards. This ALSC policy covers ALSC Decking Policy,Annex 1 equals or exceeds specific products classified by size of decking and are the stress induced by a 70 psf uniform load on the assigned a recommended span of usually 16"or 24". recommended span. The analysis assumes normal This policy is not intended to be used for the assessment load duration. or approval of decking spans in excess of 24". The range b. Point Load—the calculated maximum allowable of current grading rule specifications and species fiber stress in bending derived from ASTM D2555 requires the establishment of a uniform common and D245, or the In-grade test procedures of ALSC analytical procedure for assessing the appropriateness of Decking Policy,Annex 1 equals or exceeds the these products relative to the recommended spans. This stress induced by a 220 pound point load applied at ALSC policy establishes this uniform analytical the midpoint of one span. The analysis assumes 7- procedure. day load duration. The analysis for maximum span rating assumes the See Commentary for Alternative Methods and following design conditions: Materials for decking materials not covered by the 1. Span—Two-span continuous with load applied to ALSC policy. In addition,alternate decking materials only one span. and/or use of alternate methods of fastening decking to 2. Seasoning—Green use condition assumed to be joists has a critical impact on the resistance of lateral greater than 19%MC. loads. Equivalent strength and stiffness developed by 3. Deflection Limit—Deflection under design loads alternative materials and fastening methods is important using calculated average allowable modulus of to ensure adequate lateral capacity. elasticity shall not exceed L/180. • JOIST SIZE The format of Table 2 changed for DCA 6-15.An Span calculations in Table 2 assume a 40 psf live load, allowable simple span is given, and then an allowable 10 psf dead load,L/360 deflection limit for simple overhang for that span is calculated. The calculated spans,No. 2 grade lumber, and wet service conditions. allowable overhang is limited by the governing bending Overhang(cantilevers) calculations assume L/180 moment, deflection caused by the 220 lbs point load, or cantilever deflection with a 220 lbs point load(same as by a maximum cantilever span of one fourth of the back used for span rated decking),No. 2 grade lumber, and span(L/4). The 220 lbs point load always produces a wet service conditions. larger moment and deflection than the uniform load. See Table C2 which indicates where deflection controls American Wood Council C4 Prescriptive Residential Wood Deck Construction Guide-Commentary . overhang length. The new format was adopted in the Joist spans can cantilever past the joist bearing centerline 2018 IRC, so spans shown in DCA 6-15 are slightly up to Lo or L/4 as shown in Figure 1A and Figure 2, or different than 2015 earlier versions of the IRC. the joists may attach to only one side of the beam with • joist hangers as shown in Figures 1B.DCA 6 beam, Joist spans are based on lumber size and joist spacing. column,and footing tables assume that joists are only The span of a joist is measured from the face of bearing framed from one side of the beam,so allowing joists to at one end of the joist to the face of bearing at the other span from opposite sides of the beam without end of the joist and does not include the length of the appropriate design consideration could potentially lead overhangs. This method of measuring the"clear"span is to a condition where beam,column, and footing for ease of construction and is commonly used by capacities are exceeded. builders;however,it differs from standard engineering practice,where span is defined as the distance between Incising factors are used for refractory species including centers of required bearing,as in the 2015 NDS. To align Douglas Fir-Larch,Hem-Fir,and Spruce-Pine-Fir.Hem- the two differing definitions, 3"was subtracted from Fir spans control for these three species combinations. each allowable span in Table 2 to account for the Ponderosa Pine and Red Pine were sized using Northern difference between tabulating clear span and engineered Species design values except that the incising factor was span. not applied since Ponderosa Pine and Red Pine are not incised when treated. Since incising is not necessary for Joist spans are limited to a maximum of 18'-0"to ensure naturally durable wood(heartwood of the following appropriate design of beams and footings. If longer joist species: decay-resistant Redwood and Cedars-corner spans are designed,joist hangers,beams,posts, and sapwood is permitted if 90 percent or more of the width footings will have to be analyzed to ensure appropriate of each side on which it occurs is heartwood),Redwood load path. See the span calculator at www.awc.org for and Western Cedar are also not incised. Since Ponderosa simple span conditions without overhangs,however Pine, Red Pine,Redwood,and Western Cedar have spans shall not exceed 18'-0"when used in conjunction comparable design values,Northern Species design with DCA 6. values are used to calculate the controlling spans for these four species combinations. Table C2. Conditions Where Deflection Controls Overhang Length*. Joist Spacing (o.c.) 12" 16" 24" Species Size Allowable Overhang3(Lo) 2x66 1' - 0" 1' - 1" 1' - 3" 2x8 1' - 10" 2' - 0" 2' - 4" Southern Pine 2x10 3'- 1" 3' - 5" 2' - 10" 2x12 4' - 6" 4' - 2" 3' - 4" 2x66 0' - 11" 1° - 0" 1' - 2" Douglas Fir- 2x8 1'- 8" 1' - 10" 2' - 2" Larch, Spruce Peine Fir4 m-Fir, 2x10 2' - 10" 3' -2" 2' - 9" 2x1 2 4' - 4" 3' - 11" 3' - 3" Redwood, 2x66 0' - 9" 0' - 10" 0' - 11" Western Cedars, 2x8 1' - 5" 1' -7" 1' - 9" Ponderosa Pines, 2x10 2' - 5" 2' - 7" 2' - 8" Red Pine5 2x12 3' - 7" 3' - 9" 3' - 1" * Shading indicates overhang is deflection controlled. See Table 2 for footnotes. American Wood Council Prescriptive Residential Wood Deck Construction Guide -Commentary C5 BEAM SIZE&ASSEMBLY REQUIREMENTS are lower than design values for these refractory species, Deck beam spans are in accordance with Table 3 and can the incising factors applied to strength and stiffness • extend past the post centerline up to LB/4 as shown in values of refractory species offset the differences. Figure 3. Beams are sized based on reaction load from Therefore, span differences are minimal. Additionally, joists within the span limits shown in Table 2. Joists are Ponderosa Pine and Red Pine were sized using Northern assumed to span from one side only; therefore,joists Species design values except that the incising factor was shall not be attached to opposite sides of the same beam. not applied since Ponderosa Pine and Red Pine are not Allowing joists to span from opposite sides of the beam incised when treated. Therefore,design values for the without appropriate consideration could potentially lead Northern Species combination(includes Ponderosa Pine to a condition where beam capacity is exceeded. and Red Pine) are used to calculate spans for all of these species. With appropriate assumptions, Table 3 could be used to size beams with joists spanning from both sides. Since Glued laminated timber beams in deck applications are tabulated values for beams assume beams support clear required to be of naturally durable species or span joists with overhangs,using 2 times the joist span preservatively treated in accordance with AWPA U1. for cases where joists span symmetrically(equal joist When oil-borne preservatives are used,the glued spans) from opposite sides is acceptable. For example, laminated timber industry recommends that the NDS wet assume there are 8'-0"joists spanning from opposite service factor(CM)not be used in this specific outdoor sides of the same beam. The column in Table 3 labeled application; therefore, all glued laminated timber beams for 16'-0"joist spans can be used to size a beam in this have been designed using design values based on dry case. A similar procedure is required for designing service conditions. The adjustment factor of 0.89 in columns and footing sizes. Table 3B, footnote 1,is based on the square root of the wet service adjustment factor of 0.8 for bending design Douglas Fir-Larch,Hem-Fir and Spruce-Pine-Fir values as specified in the NDS Supplement for glued (refractory species) are combined with Redwood and laminated timber. Western Cedars (naturally durable species). Even though design values for these naturally durable species DECK FRAMING PLAN For resistance of lateral loads,the deck is assumed to act A framing plan shows the layout of the primary as a diaphragm in an open-front structure. The decking, structural system. Examples of structural elements when nailed to the joists and rim joist, acts as sheathing include:joists,beams, ledger board,posts, footings, in this diaphragm. stringers,treads, and the type, size, and spacing of ledger board fasteners. Figure C5 shows an example of a Larger aspect ratios may be permitted where calculations typical deck framing plan. show that larger diaphragm deflections can be tolerated. Copyright © 2018 American Wood Council C6 Prescriptive Residential Wood Deck Construction Guide-Commentary Figure C5. Example of a Typical Deck Framing Plan. Lumber species: Southern Pine (see Table 1) ji I `mil I-/����������/-I 7 �- LI- /Chimney or �eay Window 2x8 ledger c) v board with Y2"dia. m c� L J bolts/lag screws/anchors N a) 1- o a) @ 24"O.C. a) 5 w - ro (see Table 5) o V v co o 1--' -1 ~ 0 • o a) joist hanger: 500 lbs of n col J" m o °� b� (see Table 3A) <- m x o CO 3 3 0D do ortriple trimmer hanger:na lbs o' a �o N o) (see Table 7) coY o •ro na X na trimmer a 6 m '5 U _ �, w o (see Figure 35) a y i i O > c•ol ' rim joist N / min. '\ / \1 6x6 post \l l 1J / eta ar solid span: fs C - --IIO J E o treads: x ' (see-Table-C) LB/4 max. beam span(LB):see Table 3 single, LB/4 max. �` overhang overhang double, or triple 2x12;LB=8'-0" overall deck width: 12'-0" p. JOIST-TO-BEAM CONNECTION that an uplift load created by a 220 lbs point load at the Joist-to-beam connections must be installed to handle end of a cantilevered joist will be resisted. forces in several directions. Options 1 and 2 handle gravity loads through bearing of the joist to the beam, Connector manufacturers regard connectors with while Option 3 requires nails to resist these downward missing fasteners as improper installations and only loads. All three options have been evaluated to ensure support the product to be used with the type and number of fasteners specified in the product literature. JOIST HANGERS The loads listed in the Table 3A are derived from the Research has shown that joist hanger to ledger , worst case condition for each joist size based on Table 2 connections resist lateral loads. When permitted by the (3791bs,483 lbs, 571 lbs, and 675 lbs for Southern Pine hanger manufacturer,the use of screws instead of nails joists spaced at 24" o.c. for 2x6,2x8,2x10, and 2x12, to attach hangers to the ledger can decrease the potential • respectively). for the joist to pull away from the ledger. American Wood Council , Ni, Prescriptive Residential Wood Deck Construction Guide-Commentary C7 POST REQUIREMENTS - IRC section R407.3 specifies a minimum 4x4(nominal) The lateral force applied to corner posts is based on the wood column size; however, it would often be capacity of the connection at the brace. Therefore, the overstressed in applications covered in this document. full capacity of the brace connection is assumed to be Requiring a minimum 6x6 post in DCA 6 provides developed and applied 2 feet below the beam. adequate bearing for beams. If posts are intended to resist lateral load conditions,then posts need to be Table C4A. No. 2 Grade 4x4 Maximum Post Heights. _ designed per the NDS. An option of 8x8 nominal posts Post Heights' allows for a deck height of up to 14' in all cases shown in Table 4 footnote 5. m J J d dN Prohibiting attachment of the beam to the sides of the a Q. L LL N o y c a vaj post with fasteners only(Figure 9)ensures wood-to- t c (10 c`o C co ti wood bearing. Design of fasteners for wet-service E v a c`a m 2 co K conditions requires fairly significant capacity reductions m N C J UT 0 p� and should be evaluated by a design professional. = 0 n• CI- For 3-ply 2-inch nominal beams, a post cap is required <10' 4' 2' 3' 4' 3' since the remaining cross section at the post notch would 6' <14' 3' 2' 2' 3' 2' not be sufficient to provide adequate connection of the <18' 2' 2' 2' 2' 2' beam to the column. The connector shown in Figure 8B <10' 3' 2' 2' 4' 2' is readily available with corrosion protection and offers 8' <14' 2' 2' 2' 3' 2' uplift and lateral load resistance. <18' 2' 2' 2' 2' 2' Provisions for Alternative Methods and Materials <10' 3' 2' 2' 3' 2' allow for other post sizes and post-to-beam connections 10' <14' 2' 2' 2' 2' 2' if approved by the building official. For example, in <18' 2' 2' 2' 2' 2' order to use a 4x4 post, a post cap connection as shown <10' 2' 2' 2' 2' 2' in Figure 8B would be required. There is not enough 12' <14' 2' 2' 2' 2' 2' cross sectional area in a 4x4 to permit the let-in notch <18' 2' 2' 2' 2' 2' detail as shown in Figure 8A. Connector hardware for a <10' 2' 2' 2' 2' 2' 4x4 post is generally limited to support of 2-ply 2 inch 14' <14' 2' 2' 2' 2' 2' nominal or 4 inch nominal beams. Certain post caps may <18' 2' 2' 2' 2' NP be adjusted to fit a 3-ply 2 inch nominal member onto a <10' 2' 2' 2' 2' 2' 4x4 post,but must be special ordered. Contact a 16' <14' 2' 2' 2' 2' 2' connector manufacturer to determine if there are <18' 2' 2' 2' 2' NP solutions for connecting a single 3 inch nominal member <10' 2' 2' 2' 2' 2' onto a 4x4 post. See Table C4A: 4x4 Post Heights. 18' <14' 2' 2' 2' 2' NP Diagonal bracing can contribute to the stiffness of the <18' 2' 2' NP 2' NP deck and, therefore, cause additional lateral loads on the 1.Assumes 40 psf live load, 10 psf dead load,Ls/4 and L�/4 posts. Since center posts receive more vertical load than overhangs,No 2.grade and wet service conditions. corner posts, additional lateral load can cause overstress. 2.Incising assumed for Douglas Fir-Larch, Hem-Fir,and Spruce-Pine- ' For this reason,Figure 10 does not show the use of Fir. ' diagonal bracing on center posts. FOOTINGS for the footing size an iterative process. The following Footing sizes are based on the assumptions of 1,500 psf equations may be used to size footings for other soil bearing capacity and 2,500 psi compressive strength assumptions (see Figure C12): of concrete which are the minimum values based on IRC Tables R401.4.1 and R402.2. See Table C4B for footing sizes with higher soil bearing capacities. A concrete weight of 150 pcf is also assumed, which makes solving American Wood Council C8 Prescriptive Residential Wood Deck Construction Guide-Commentary Post load(lbs): Figure C12. Footing Dimensions and Variables. _ z R =S0/LJoist +L,Joist Overhang\(LBeam)+150 B T R or � z R =J 5 0/I'Joist .� L (Joist Overhang \�Beam +150 �D T s•s P 6912 where: L units are in feet and B,D, and T are in inches. T II i Square footing(in.): B=12 R (soil capacity) B or D Round footing(in.): D =12 4R (soil capacity)7t Footing thickness(in.): T>P; T> (BorD)-5.5 2 Table C4B. Footing Sizes for Higher Soil Bearing Capacities. 2000 psf 2500 psf 3000 psf m J -, C) a) O) a) C) C) C C = C C C c C U) N 0. Q. O W 0 C) U) O O 0 C) 0) O N 0 C) U) N L. c u. C C LL E LL CO L_ ° IOL C E N i O V co_ i O a -0 R L.O O v O m 0 co LLB 7 � 3 LLI- O - co LLH m co ceN re NW 510' 15" 13"x 13" 6" 14" 12"x12" 6" 12" 11"x11" 6" 6' 514' 18" 16"x16" 7" 16" 14"x14" 6" 15" 13"x13" 6" 518' 20" 18"x18" 8" 18" 16"x16" 7" 16" 15"x15" 6" 510' 17" 15"x15" 6" 16" 14"x14" 6" 14" 13"x13" 6" 8' 514' 21" 18"x18" 8" 18" 16"x16" 7" 17" 15"x15" 6" 518' 23" 21"x21" 9" 21" 18"x18" 8" 19" 17"x17" 7" .510' 19" 17"x17" 7" 17" 15"x15" 6" 16" 14"x14" 6" 10' 514' 22" 21"x21" 9" 20" 18"x18" 8" 19" 17"x17" 7" S18' 26" 23"x23" 11" 23" 21"x21" 9" 21" 19"x19" 8" 510' 21" 19"x19" 8" 19" 17"x17" 7" 17" 15"x15" 6" 12' 514' 25" 22"x22" 10" 22" 20"x20" 9" 20" 18"x18" 8" S18' 29" 26"x26" 12" 26" 23"x23" 11" 23" 21"x21" 9" 510' 23" 21"x21" 9" 20" 18"x18" 8" 19" 17"x17" 7" 14' 514' 27" 24"x24" 11" 24" 22"x22" 10" 22" 20"x20" 9" S18' 31" 28"x28" 13" 28" 24"x24" 12" 25" 22"x22" 10" 510' 25" 22"x22" 10" 22" 19"x19" 9" 20" 18"x18" 8" 16' S14' 29" 26"x26" 12" 26" 23"x23" 11" 24" 21"x21" 10" S18' 33" 30"x30" 14" 30" 26"x26" 13" 27" 24"x24" 11" 510' 26" 23"x23" 11" 23" 21"x21" 9" 21" 19"x19" 8" 18' 514' 31" 28"x28" 13" 28" 24"x24" 12" 25" 22"x22" 10" S18' 36" 32"x32" 16" 31" 28"x28" 13" 28" 25"x25" 12" American Wood Council Prescriptive Residential Wood Deck Construction Guide-Commentary C9 Footnote 2 of Table 4 allows for the footing thickness Additional footing options were added to the 2012 and size to be reduced for corner posts since the version of DCA 6 Figure 12. One allows for a 12" • tabulated values assume center posts,which resist more diameter concrete stem to reduce the amount of concrete vertical load. The factor is 0.9 because of additional load required. The second provides an option for a fully applied from the diagonal(knee)brace. embedded post in concrete with a gravel base to allow for water drainage. However,note that when the Coordinating the footing thickness with post base and embedded post option is used to resist lateral loads, the anchor requirements means ensuring that post anchor post must be designed per the NDS. length does not exceed the thickness of the footing. LEDGER ATTACHMENT REQUIREMENTS perpendicular to grain stresses if the outer edges of the Fastener spacing requirements in Table 5 are based on ledger are constrained by bolts. 2015 IRC R507.2.1,which is based on testing at Virginia Tech and Washington State University(Carradine et al., The requirement for minimum distance between the top 2006). Testing was conducted for three common deck of the ledger and the bottom row of fasteners(Figure 19) ledger constructions using ''h" diameter lag screws and is based on NDS 3.4.3.3(a)for shear design at bolts. In the tests,two types of band joist materials were connections. When the connection is less than five times used: 2x10 Spruce-Pine-Fir(SPF) lumber and 1-inch- the depth, 5d,of the bending member from its end,the thick Douglas-Fir(DF)laminated veneer lumber(LVL) adjusted design shear is calculated as follows: rim board. SPF has a relatively low specific gravity of G 2 =0.42, so other denser species groupings (e.g.,Hem-Fir, Vr,=L..F bde de Douglas-Fir-Larch, and Southern Pine)can be - conservatively substituted. Thicker LVL products with Solving for de yields the following: equivalent specific gravities of 0.50 or greater can be conservatively substituted for the LVL band joist de3=3 VI d2/(2 F',b) material tested. In addition,manufactures of EWP rim boards may publish capacity and spacing requirement Assuming a Hem-Fir No. 2 ledger, the reference for their rim boards that can be used when designing horizontal shear design value,F,,= 150 psi. The adjusted attachment of ledgers to rim boards. shear design value,Fly,is based on a wet service factor, According to IRC R311.3.1,the distance from the top of CM=0.97, and incising factor,C;=0.80. The maximum the threshold to the to of deck boards cannot exceed allowable lateral design value of 725 lbs for'h"bolts and 1'/2". If a door does not swing over the landing or deck, 385 lbs for'h" lag screws-is based on testing at the step-down can be up to 73A". The ledger can be Virginia Tech and Washington State University lowered for improved drainage, subject to meeting (Carradine et al.,2006). Spacing calculations assume maximum step-down heights for accessibility and means that bolts or lag screws at the end of the ledger have half of egress, edge distance and spacing requirements,and the tributary area of interior bolts or lag screws and that shear design at connection requirements of NDS the shear at interior bolts or lag screws is half of the shear 3(a). interior bolt or lag screw reaction. Therefore,the 3.4.3. minimum value of de is calculated assuming Vr equals The basis for edge distances and spacing between rows one-half of the allowable lateral design value for the 1/2" (Figure 19) is NDS Tables 11.5.1C and 11.S.1D, bolts(725/21bs) or /2 lag screws(385/2 lbs). Resulting respectively, for perpendicular tograin conditions. Per values of de are as follows: p Y' p %" bolts 'A" lags NDS Table 11.5.1C, edge distance is 4D(where D is 2x8 de=5.47" de=4.43" • fastener diameter)for the loaded edge. For diameter 2x10 de=6.43" de= 5.21" bolts,4D=2" edge distance. 2x12 de=7.33" de=5.9" Per NDS Table 11.5.1D, spacing between rows is based The problem with these effective depths is that a 2x8 on the B/d ratio of the fastener. For a 1'/2" ledger and rim ledger connected to a 2x8 band joist with bolts will not board,t/d= 1%2"/ 1/2" =3 and the minimum spacing is work(see Figure C 19). (St+ 10D)/8= 19/16"—this is rounded up to 15/8".Per 11.5.1.3 of the NDS,the maximum spacing between Possible solutions for the 2x8 band joist include: fasteners is 5". This requirement is based on potential 1) Non-ledger deck. shrinkage of the ledger which could create tension American Wood Council per. C10 Prescriptive Residential Wood Deck Construction Guide-Commentary 2) Require lag screws for 2x8 band joist and revise Continuous flashing is required as shown in Figure 14 to . required de=41/2" as shown in Figure 19. prevent water intrusion behind the ledger. One 3) Allow bolted connections for 2x8 band joist if alternative to this detail would be continuous flashing bolt spacing is reduced to the same as that for with a drip edge;however,this would be labor intensive lag screws(only applies to 1/2"bolts without because the flashing would require notching at every stacked washers as shown in Table C5)as deck joist location. shown in Figure 19. 4) Reduce bolt spacing requirements for 2x8 ledger Connection of ledgers to existing empty or hollow to 2x8 band joist.When de=4.5",Vr=2021bs, masonry cell blocks(Figure 15)is generally not practical and the back-calculated adjustment factor is because most manufacturers of concrete block anchors 0.56. Based on Table 2,the maximum joist span do not publish allowable shear values for a ledger for a 2x8 is 10'-6". This results in revised connected to empty hollow masonry block of unknown spacing for'h"bolts as shown in Table C5. compression and breakout strength. Due to the uncertainty and lack of test data for this application,use To achieve the minimum spacing requirements noted of a non-ledger deck is recommended(see Figure 21). above, a nominal 2x8 ledger is required even if the deck joists are 2x6's. 1-1/2"decking 3/4"floor Table C5. Revised Bolt Spacing Requirements =�—t for 2x8 Ledgers to 2x8 Band Joists. 2"min. .,►�i V. „ Joist Span .NI 4-1/2 < 5-1/2' 5 max. & 1-518 min. NG 6'-0" & 6'-1"to 8'-1"to 10'-1" to ,i,ill — less 8'-0" 10'-0" 12'-0" 2" min. '/2' bolt 32" 24" 19" 16" 0'!=0 '/2' bolt with 27" 20" 16" 13" 2x8 band joist stacked washers 2x8 ledger Figure C19. Edge Distance and Spacing Requirements for 2x8 Band Joist and 2x8 Ledger. NON-LEDGER DECKS—FOR RESISTING the primary structure but still relies on the primary f VERTICAL LOADS structure to resist lateral loads;whereas,a free-standing The provisions of DCA 6 assume that the primary deck is both vertically and laterally independent. ( structure is used for lateral stability. A non-ledger deck, as defined in this document,is vertically independent of DECK LATERAL LOADS tension devices are still shown in DCA 6. In lieu of the Item 10 of DCA 6 Minimum Requirements& prescriptive hold-down tension devices specified,an Limitations states that the document does not address alternate engineered or approved connection detail , lateral stability issues beyond those addressed in Section would be required. • R507.2.4 of the IRC. Where deck joists are perpendicular to the house floor IRC R507.1 requires anchorage of the deck to the joists,blocking between house joists and boundary primary structure to resist lateral loads. Further,the IRC nailing of the house floor diaphragm to the blocking is includes hold-down tension devices as a prescriptive required for the installation of hold-down tension means to achieve compliance with the lateral load devices. connection requirements without requiring engineering. See IRC Section R507.2.4. Figure R507.2.3(2)was For connecting the hold down tension devices to I joists, added to the IRC in the 2015 edition,but equivalent a detail recommended by the Wood I-Joist Manufactures performance to the existing prescriptive solution has not Association and similar to Figure R507.2.3(1)of the been demonstrated. Consequently,two 1500 lbs capacity IRC,is provided. American Wood Council Prescriptive Residential Wood Deck Construction Guide-Commentary C11 however,the IRC does not prescribe diagonal bracing. • For non-ledger decks,Figures 22 and 23 prescribe three See Post Requirements for more on the implications of • methods of transferring lateral loads from deck joists to diagonal bracing. the rim board:joist hangers (as shown),blocking, or use of framing angles. This connection is to transfer forces Figures 22 and 23 show nailing from above through acting parallel to the house. A connection equal to the floor sheathing and into floor joists or blocking between diaphragm capacity of single layer diagonal boards, or floor joists of the house.An equivalent connection from approximately 300 plf, is required. underneath is permissible using framing angles and short fasteners to penetrate into the floor sheathing. Diagonal(knee)bracing is commonly used on decks to help resist lateral forces and provide increased stiffness; GUARD REQUIREMENTS exposure to falls over the top of the guard due to Figure 24 requires that openings not allow the passage of individuals standing on deck seats. a 4" diameter sphere. However, it does not address openings underneath a fixed deck bench used in place of IRC Table R301.5 requires guard in-fill components (all guards.All openings, including those underneath those except the handrail),balusters, and panel fillers to benches used in place of guards, shall not allow the be designed to withstand a horizontally applied normal passage of a 4" diameter sphere. load of 50 pounds on an area equal to 1 square foot. This load need not be assumed to act concurrently with any Additionally, if fixed seating is adjacent to guards,the other live load requirement. Baluster connection guard height should be measured from the seat rather requirements shown in Figure 24 have been designed to than the deck surface. While 2015 IRC Section R312.1.2 resist that load. allows for the guard height to be measured from the walking surface,DCA 6 requires measurement from fixed seating as a best practice. This will help minimize GUARD POST ATTACHMENTS FOR REQUIRED This section requires deck guard posts to be at least 4x4 GUARDS nominal with a reference bending design value not less Both the IRC and International Building Code (IBC) than 1,100 psi to ensure sufficient bending stress in the specify that guardrails and handrails be capable of post. Assuming the lever arm is 39.5" (36"+ 1'A" deck resisting a minimum concentrated live load of 200 lbs board+2" edge distance),the bending moment is 39.5" applied in any direction for required guard rails(See IRC x 200 lbs=7,900 in-lbs. Bending stress, fb, is calculated R312.1). Commonly used residential guardrail post as follows: connections were laboratory tested at the required load level for a code-conforming assembly per the IBC M/S(4X4)=7,900 in-lbs/7.146 in3 = 1,106 psi. (Loferski et al.,2006). A commercially available connector,typically used in shear wall construction,was No. 2 grades of all Table 2 species meet this requirement tested in a post-to-deck residential guardrail assembly. with the following assumptions. The adjusted bending The connection passed a load test based on code design value,F'b, is based on a wet service factor, CM= provisions for a"tested assembly."Connection details in 0.85,and incising factor, Ci=0.80(Douglas Fir-Larch, Figures 25 and 26 reflect these test results. Hem-Fir, Spruce-Pine-Fir).A load duration factor, CD= 1.6,is assumed for consistency with the hold-down A minimum requirement of 1,800 lbs for the hold-down device used to connect the guard to the joist. connector ensures adequate capacity(Loferski et al., 2005)for a 36"maximum rail height. A higher rail Figures 25 and 26 show minimum and maximum height requires design of a higher capacity connector. spacing requirements for bolts in deck joists and deck . Manufacturers' tabulated values for hold-down rim boards. The 5"maximum spacing is per NDS 11.5.1.3. This requirement is based on potential connectors typically include a load duration(CD) q � " increase of 60%since connectors for shear walls are shrinkage of the joist or rim board which could create used to resist wind and seismic loads. The 200 lbs tension perpendicular to grain stresses if the outer edges concentrated load requirement for guard rails is assumed of the deck joist or rim are constrained by bolts. To to be a 10 minute load duration(e.g. it would not see a achieve the minimum spacing requirements, a nominal maximum 200 lbs outward load for more than 10 2x8 or wider(deeper)outside joist or rim board is minutes cumulatively in its lifetime). Therefore, CD=1.6 required. is used for hold-downs in this application. American Wood Council Prescriptive Residential Wood Deck Construction Guide - Commentary C12 STAIR REQUIREMENTS lbs is distributed across 2 inches(e.g. 150 pli),based on Figure 29 shows 5/4 boards spanning 18" or less. As L/288 deflection criteria(ICC ES Acceptance Criteria noted under DECKING REQUIREMENTS 174 requires '/8" deflection limit: 36"/1/8"=288).No • commentary, specific products classified by size as species will calculate for that span using 2x6 No. 2 decking are usually assigned a recommended span of 16" grade. or 24". Solid stringers were analyzed as simple span beams Additionally,IRC Table R301.5 footnote(c)requires a using the horizontal span not the actual stringer length. 300 lbs concentrated load check on stair treads.Analysis Cut stringers were analyzed with 5.1" depth which is revealed that 2x8 No. 2 Southern Pine works for a 34'/2" based on 7.75:10 rise to run ratio. A size factor,CF, of span(36" minus 3/4"bearing at each end)when the 300 1.0 is used since 2x12 is the size basis. STAIR FOOTING REQUIREMENTS eleven#8 wood screws(16d box or common threaded Stair stringers should be supported by bearing at the end nails would be comparable). where the stairway meets grade.The detail shown assumes a 40 psf live load and 10 psf dead load over a While bolts are sometimes used for this detail,proximity tributary area of 18" and one-half of the maximum span to the end of the stringer could lead to splitting of the of 13'-3"permitted for solid stringers. This calculates to stringer—especially cut stringers.The 2x4 bearing block 500 lbs. For Southern Pine, seven#8 wood screws alleviates this situation.However,in addition to the would be required.Northern Species would require bearing block,bolts would also be required to provide lateral support if a guard post is used. FRAMING AT CHIMNEY OR BAY WINDOW less than that shown in Table C7a, a double trimmer joist IRC R502.10 on framing of openings states: "Openings is also permitted. in floor framing shall be framed with a header and trimmer joists. Where the header joist span does not Bending and shear were checked to determine the exceed 4 feet,the header joist may be a single member reduction in a double trimmer joist span when carrying a the same size as the floor joist. Single trimmer joists 6'header. For a simple span beam,with a concentrated shall be used to carry a single header joist that is located load offset from the center,maximum moment is within 3feet of the trimmer joist bearing. Where the calculated as Pab/LJ and maximum shear is calculated as header joist span exceeds 4 feet,the trimmer joists and Pb/Li,where P is the concentrated load based on the the header joist shall be doubled and of sufficient cross tributary area carried by the header,b=LJ—a,and Li is section to support the floor joists framing into the the trimmer joist span. header." Moment controlled for this analysis in determining a.. Trimmer Joist Size and Span Limited by Concentrated While shear was evaluated,the NDS permits the shear Load from the Header load to be reduced within a distance"d"(equal to the Where the header frames into the trimmer joist,a joist depth)from the end of the joist. With that concentrated load is created. This condition was reduction, shear did not control any of the spans evaluated assuming one ply of a double trimmer joist evaluated. carries the uniform load and one ply carries the point load from a 6'header. The analysis revealed that the distance from the end of the trimmer joist to the point where the header frames into it—designated as dimension"a"—must be limited. The maximum distance was calculated based on joist spans given in Table 2. A maximum distance of a=3'was chosen to cover common framing conditions. Triple trimmer joists are required on each side of the header if joist spacing is 12" or 16" o.c.,or if the trimmer joist span exceeds 8'-6"; otherwise a double trimmer joist is permitted. If"a"is American Wood Council Prescriptive Residential Wood Deck Construction Guide-Commentary C13 Table C7a. Maximum Distance "a" from Trimmer Joist End to a Point where a 6' Header Frames into Table C7b. Maximum Trimmer Joist Span (Li) Based a 2-ply Trimmer Joist. on Distance "a"from the Trimmer Joist End to the Point where the Header Frames into the Trimmer.1'4 Species Trimmer Size amax 2-2x6 15" Ledger Species Size a = 1' a=2' a = 3' 2-2x8 17" 2x85 5'-9" 7'-5" 8'-11" Southern Pine 2-2x10 19" Southern Pine 2x10 9'-2" 10'-11" 12'-T' 2-2x12 25" 2x12 9'-5" 11'-2" 12'-10" 2-2x6 11" Douglas Fir- 2x85 4'-6" 6'-0" 7'-6" Douglas Fir-Larch, Hem- 2-2x8 14" Larch,Hem-Fir, 2x10 6'-10" 8'-6" 10'-1" Fir, SPF1 2-2x10 16" Spruce-Pine-Fire 2x12 7'-0" 8'-9" 10'-4" 2-2x12 19" Ponderosa Pine3, 2x85 4'-3" 5'-9" 7'-3" 2-2x6 10" Red Pine3, 2x10 6'-5" 8'-1" 9'-8" Redwood, Western 2-2x8 13" Redwood, Cedars, Ponderosa Pine2, 2-2x10 16" Western Cedar 2x12 6'-7" 8'-3" 9'-10" Red Pine2 2-2x12 18" 1. Assumes 6'header span.See Figure 35 for header,trimmer, and ledger framing details. 1. Incising assumed for Douglas Fir-Larch,Hem-Fir,and 2. Incising assumed for Douglas Fir-Larch, Hem-Fir,and Spruce- Spruce-Pine-Fir. Pine-Fir. 2. Design values based on Northern Species with no incising 3. Design values based on Northern Species with no incising assumed. assumed. 4. Shading indicates where triple trimmers are required.See text The trimmer hanger capacities listed in Table 7 are based for alternate 2-ply trimmer conditions. on Southern Pine joist spans at 12" o.c. or 16" o.c. 5. Applies to 2x6 trimmer joist spans as well. spacing(whichever controls). The reaction is a Table C7c. Trimmer Joist Hanger Vertical Capacity combination of the concentrated header load Pb/14 and Based on Trimmer Span. the tributary uniform load between the trimmer and the Trimmer Span Minimum Capacity, lbs next adjacent joist. Another way of tabulating trimmer 8' 660 hanger capacities is shown in Table C7c based on 10' 860 trimmer spans. Table C7c is based on the header framing 12' 1060 into the trimmer at 1' (a=1', see Figure 35). Table C7c will be conservative for larger protrusions (larger"a" 14' 1260 values.)Linear interpolation of tabulated values is 16' 1325 permitted. 18' 1430 Trimmer Joist Span Limited by Concentrated Load on Examples the Ledger 1) Assume a 2x10 Redwood joist spanning 12'-0" at Bolts or lag screws used to attach the trimmer hanger to 16" o.c. (per Table 2) framing around a 5'wide by 2'-6" the ledger are required to fully extend through the ledger deep chimney. Set a 6' header 3' from the end of the into the band joist or rim board. If a typical face trimmer joist. A triple trimmer joist is required since the mounted hanger is installed where only nails are used to span exceeds 8'-6". If the trimmer hanger does not attach attach the hanger to the ledger,the ledger would carry a through the ledger to the rim board or band joist, the large portion of the load. Since a concentrated load trimmer joist span is limited to 9'-8" per Table C7b. would be created on the ledger, it would be resisted by Several solutions exist: the bolts at the end of the ledger. As discussed under - Reduce all joist spans to 9'-8". LEDGER ATTACHMENT REQUIREMENTS,the - Li/4=2'-5" so LJ+L4/4= 12'-1" total joist length, provisions for minimum distance,de,between the top of which would provide the same square footage. • the ledger and the bottom row of fasteners (Figure 19) is - Place a post under the center of the header to reduce based on NDS 3.4.3.3(a) for shear design at connections. the header span. Based on this analysis,trimmer joist lengths would need to be limited to the maximum trimmer joist spans shown 2) Assume a 2x8 Western cedar joist spanning 8'-0" at in Table C7b,regardless of the trimmer joist species or 24" o.c. (per Table 2) framing around a 5'wide by 1.5' number of plies. Since this analysis is based on a simple deep bay window. Set a 6'header 2' from the end of the span trimmer joist, a trimmer joist with an overhang of trimmer joist. A double trimmer joist is permitted since up to L4/4 would be conservative. The load on the end of the spacing is 24" o.c. If the trimmer hanger does not the cantilever would reduce the reaction at the ledger. attach through the ledger to the rim board or band joist, American Wood Council C14 Prescriptive Residential Wood Deck Construction Guide-Commentary the trimmer joist span is limited to 5'-9"per Table C7b. 6" deep bay window. Set a 6'header 2' from the end of Several solutions exist: the trimmer joist.A double trimmer joist is permitted - Reduce all joist spans to 5'-9". since a=24"which is less than amp=25" in Table C7a. - Place a post under the center of the header to reduce However,if the trimmer hanger does not attach through the header span. the ledger to the rim board or band joist,the trimmer - Increase joist size to 2x10 which will span 8'-1"per joist span is limited to 11'-2" per Table C7b. Several Table C7b. solutions exist: - Reduce all joist spans to 1 l'-2". 3) Assume a 2x12 Southern Pine joist spanning 18'-0" - Place a post under the center of the header to reduce at 12" o.c. (per Table 2) framing around a 5'wide by 1'- the header span. REFERENCES ASTMF547-06 Standard Terminology of Nails for Use with Wood and Wood-Base Materials,ASTM,West 2015 International Building Code(IBC), International Conshohocken,PA,2012. Code Council(ICC),Washington,DC,2015. AWPA Book of Standards,American Wood Protection 2015 International Residential Code(IRC),International Association,Birmingham,AL,2017. Code Council(ICC),Washington, DC,2015. Carradine,D.M.,Donald Bender,Joseph R. Loferski, AC174 Acceptance Criteria for Deck Board Span and Frank E. Woeste. "Residential Deck Ledger Ratings and Guardrail Systems(Guards and Handrails), Connection Testing and Design." Wood Design Focus. International Code Council Evaluation Service, Vol. 16,No. 2. Forest Products Society.Madison,WI. Washington,DC,2014. Summer 2006. ANSI/AWC NDS-2015 National Design Specification Loferski, Joseph R.,Dustin Albright,and Frank E. (NDS)for Wood Construction,American Wood Council, Woeste. "Tested Guardrail Post Connections for Leesburg,VA,2015. Residential Decks." Wood Design Focus. Vol. 16,No.2. Forest Products Society. Madison,WI. Summer 2006. ASTMD245-06 Standard Practice for Establishing Structural Grades and Related Allowable Properties for Loferski,Joseph R. and Frank E. Woeste. "Strong Rail- Visually Graded Lumber,ASTM,West Conshohocken, Post Connections for Wooden Decks."Journal of Light PA,2011. Construction.Williston,VT. February 2005. ASTM D2555-06 Standard Practice for Establishing Policy for Evaluation of Recommended Spans for Span Clear Wood Strength Values,ASTM West Rated Decking Products,American Lumber Standard Conshohocken,PA, 2001. Committee,Germantown,MD. 2004. American Wood Council RECEIVED MOUNT POSTS DEC 1. 5 202i CITY OF TIGARD i BUILDING DIVISION . e- '' ''''-''< Fe26 I CABLE RAILING } ,,:::,,,,_,„..„.„_H wet• MOUNT BRACKETS & PANELS -- Fortress Posts must always be secured to the deck framing and should never be attached to only the deck boards. ATR Wood Cap--- _i ATR OPTION 1 . Spacer Epoxy UNIVERSAL BRACKETS Cap Rail Clip— Spacer-- Flat Accent Rail Wood or Composite Top Rail i * Cap Rail Clip UB-05 ♦i•''- - - - - - --'1♦ UB-05 ♦ Ld UB-05 4 4- -4 4 E a) F-L ci p - 0 N T I 50 UNIVERSAL BRACKETS: ANGLE/MITER • Ball Cap Pressed Dome Cap — Accent Top Rail UB-05 Bracket —UB-05 Bracket UB-OSAngleAdapter UB-05 Angle Adapter UB-05 Cap 0— UB-05 Cap UB-OS Angle Adapter — UBOS Angle Adapter L Vertical or Panel 69-1/2'or 93-1/2" UB-05 Bracket U8-05 Bracket Base Cover 2'X 2'or 3'X 3°Iron Posts with Base — Ball Cap g UB-05 Bracket — UNIVERSAL BRACKETS: iBo5 AngleAdapter STAIR WITH UB-05 ANGLE Accent Top Rail ADAPTER Pressed Dome Cap IIII UB-05 Cap eEL UB-05 Bracket — UB-05 Angle Adapter t 111101 UB-05 Bracket UB-05 Angle — Base Cover Adapter Vertical Stair Cable'anel UB-05 Cap • UB-05 Angle I A� Adapter B-05 Brack 2"X 2'or 3'X 3"Iron Posts with Base 57 . . . 4 I