Specifications ea c./t5$ Crc' / 7
1 g 3 S r s •..i ,S' //s Fe.,..�
FIELD TECHNICAL INFORMATION
Application recommendations for work at the wall or ceiling
4 Suspension Systems for
6/05. Acoustical Lay -in Ceilings
THIS DOCUMENT HAS BEEN •
APPROVED BY THE BUILDING
DEPARTMENT
_ . -.. . .
This document provides the various
standards for the installation of sus -
General Recommendations
pension systems for acoustical lay -in
• Referenced sources per hierarchy: 2003 IBC (International Building Code),
ceilings. Incorporation of this document American Society of Testing Materials (ASTM C 635, ASTM C 636),
will provide a more uniform standard for American Society of Civil Engineers (ASCE 7 -02) and Ceilings and Interior
, Systems Construction Association (CISCA).
installation and inspection. This document • Partitions that are tied to the ceiling and all partitions greater than 6 feet in
is designed to accomplish the intent of height shall be laterally braced to the structure. Bracing shall be indepen-
dent of the ceiling splay bracing system. s. r -e !B!: sec, :),: '62 7.1.,:'
the International Building Code (IBC) with For further information on bracing of non -load bearing partitions refer to
regard to the requirements for seismic NWCB technical document #201.
• All main beams are to be Heavy Duty (HD). sa ce ,isc_ - -o ,;%S s
design category D for suspended ceilings • All cross tees shall be capable of carrying the design load without exceed -
and related items. Unless supported by ing deflection equal to 1/360 of its span. so:,,- A c zonG:: 2
• These recommendations are intended
engineering or approved by local build
for suspended ceilings including grid,
ing department, the suspension system i panel or tile, light fixtures and air terminals
weighing no more the 4 lbs. per square
shall be installed per the requirements for foot. so.,,re ASCE 7 ,e,7% s
Seismic Design Category (SDC) D, E max,mum 3' �r
(76mm) y • All wire ties are to be three tight turns
9 ry ( )
around itself within three inches. Twelve
and F per the IBC. Manufacturers' gage Hanger wire spaced 4 foot on center
recommendations should be followed (figure 1). so „ e < s c 6,- :
. n • Changes in ceiling planes will require
positive bracing.
figure1 - LS,c- ,. ce _. '
NORTHWEST WALL & CEILING BUREAU SUSPENSION SYSTEMS FOR ACOUSTICAL LAY -IN CEILINGS
figure 2 Lateral Force Bracing (figures 2 and 3)
Lateral force Bracing
• Ceilings constructed of lath and plaster or gypsum board, screw or nail at-
tached to suspended members that support a ceiling on one level extending
from wall to wall shall be exempt from the lateral force bracing requirements.
45° or lees , - 45 w 1438
Source CISCA zones 3 -4
• Lateral force bracing is the use of vertical struts (compression posts) and
- 12 gape splay wires (see figure 2).
- - -— �
splayed
I _ brace • Lateral force bracing is required for ceilings over 1,000 square feet and not
40° or less t ` 45° or lase wires
required for ceilings less than 1,000 square feet provided they are surrounded
by four walls and braced to structure. Source ASCE 7 -02 section 9.6 2.6.2.2 Item c
— Cross lee Main beam — • Lateral Force Bracing shall be 12 feet on center (maximum) and begin no
farther than 6 feet from walls. Source CISCA Seismic zones 3-4
• Splay wires are to be four 12 gage wires attached to the main beam. Wires
are arrayed 90° from each other and at an angle not exceeding 45° from the
plane of the ceiling. Source COCA Seismic zones 3 -4
• Splay wires are to be within 2 inches of the connection of the vertical strut to
suspended ceiling. Source CISCA Seismic zones 3 -4
figure 3 • Rigid bracing may be used in lieu of splay wires. Source ASCE section 9.6.2.6.2.2
Maximum Recommended Lengths for
Vertical Struts • Ceilings with plenums less than 12 inches to structure are not required to
have lateral force bracing. Source Portiand Building Department
• Vertical struts must be positively attached to the suspension systems and the
EMT CONDUIT structure above. Source CISCA 3 -4
'/z" EMT conduit up to 6'0" • The vertical strut may be EMT conduit, metal studs or a proprietary compres-
sion post (see figure 3).
3" EMT conduit up to 8' 6"
1" EMT conduit up to 10' 0" Wall Moldings (figure 4)
1 METAL STUD • Wall moldings (perimeter closure angles) are required to have a horizontal
• flange 2 inches wide, unless alternate methods are approved prior to instal-
1%" metal stud (25 gage) up to 6' 2" lation by the local building department and the designer of record. One end
2'/z" metal stud (25 gage) up to 10'6" of the ceiling grid shall be attached to the wall molding, the other end shall
have a Y4 inch clearance from the wall and free to slide. Source ASCE 7 - section
Source Portland Building Department 9.6.2.6.2.2 item b
• The grid shall be attached at two adjacent walls (pop rivets or approved
Note: Plenum areas greater than 11'0" will require method). Source CISCA Seismic zones 3 -4
engineering calculations.
• There shall be a minimum s/ inch clearance from the end of the grid system
at un- attached walls. Source ASCE 7 -02 section 9.6.2.6.2.2 item b
Spreader Bars (figure 4)
• Spreader (spacer) bars or other means approved by local building depart -
figure 4 ment shall be used to prevent the ends of the main beams at perimeter walls
Wall Molding Requirements from spreading open during a seismic event. Perimeter wires shall not be in
lieu of spreader bars. Source CISCA Seismic zones 3 -4
• Wire tying is an acceptable alternative to spreader bars.
ma e' 1202 mm)
WALL • Spreader bars are not required if a 90 degree intersecting cross or main is
within 8 inches of the perimeter wall.
0 `o Spreader bar or
other Sable
608881, r440irae t0
'Gs I � keaa�tr� Hanger (Suspension) Wires (figures 5a and 5b)
components from
m inimum scseao1n0 Wan
3/4 (10 =V
I � f at unattached wets ` . • Hanger and perimeter wires must be plumb within 1 in 6 unless (figure 5a)
counter sloping wires are provided-(figure 5b). Source AST1✓ C 636 section 2.1.4
`a • Hanger wires shall be 12 gage and spaced 4 feet on center or 10 gage
spaced 5 feet on center. Source ASTM C 636
• Any connection device at the supporting construction shall be capable of car-
rying not less than 100 pounds. Source CISCA zones 3 -4
NORTHWEST WALL & CEILING BUREAU • SUSPENSION SYSTEMS FOR ACOUSTICAL LAY.IN CEILINGS
• For essential facilities, hanger wire connections must be capable of carrying figure 5a
200 pounds and bracing (splay) wires shall be capable of carrying 440 pounds, "° I
shot -in anchors in concrete are not permitted for bracing wires. source Depart-
' ment of State Architects (DS.A) /R /.. -3
• • Bracing wires shall be attached to the grid and to the structure in such a man-
ner that they can support a design load of not less than 200 pounds or the
actual design load, with a safety factor of 2, whichever is greater (figure 6b). mmm.a - - •
Source CISCA zones 3 -4
• Powder driven fasteners must be approved for the appropriate loading. _ -_
SoulceASCE 7 -02 sect +on 9.6.1.6.5 r = • Terminal ends of each main beam and cross tee must be supported within 8
inches of each wall with a perimeter wire (see figure 4 & 5 b). Source CISCA zones .3.4
figure 5b • Countersloping
Electrical fixtures f r ..
/' / 3pemry \
• Light fixtures weighing less than 10 pounds shall have one 12 gage hanger `' 0` .
wire connected from the fixture to the structure above. This wire may be slack. �'
SNm un mom
enpY I upb
Source CISCA Seismic zones 3 -4 , 1)
• Light fixtures weighing more than 10 pounds and less than 56 lbs. shall have -- , I ' - - -- - -
two 12 gage wires attached at opposing corners of the light fixture to the
structure above. These wires may be slack. Source CISCA Seismic zones 3 -4.
• Light Fixtures weighing more than 56 lbs. shall be supported by directly from
the structure above. These wires must be taut. Source CISCA Seismic zones 3 -4
Pendant mounted fixtures shall be directly supported from the structure above figure 6a
• using a 9 gage wire or an approved alternate support without using the ceiling Vertical hanger wire attachment
suspension system for direct support. so urce CISCA Seismic zones 3 -4
Shot -In enchcr ( i] 3/4'
• Tandem fixtures may utilize common wires.
Structural concrete —j L_
Ceiling clip m /
Mechanical Services
(II
• Terminals or services weighing 20 lbs. but not more than 56 lbs. must have two 3 turns •
12 gage wires connecting them to the ceiling system hangers or the structure
Vertical hanger wire
above. These wires may be slack. source CISCA Seismic zones 3 -4 __
• Terminals or services weighing more than 56 lbs. must be independently figure 6b
supported directly from the structure above. These wires must be taut.
- Souce CISCA Seismic zones 3 -4 Splayed seismic bracing wire attachment
Seismic Separation Joints (figure 7) 5/18• drill-in expansion anchor —t
minimum
For ceiling areas exceeding 2500 square feet, a seismic separation joint or full Structural concrete I 46•
height wall partition that breaks the ceiling shall be provided unless analyses are Steel strap 1 • wide x 2' long x
performed of the ceilings bracing system, closure angles and penetrations to pro- 12 gage minimum
vide sufficient clearance. Soaks ASCE 7 -02 heir 9.6.2.6.2.2 d 3 turns i
k r' ,
The layout and location of the seismic separation joint shall be per the designer Splayed seismic bracing wire
of record and noted on the plans. If a seismic separation joint is required by the
designer, the designer may use the generic joint detailed in this document or a pro-
prietary joint. The amount of free movement (gap design) shall be per the designer figure 7
of record.
Special Inspections
Special inspections may be required by the jurisdiction or municipality. Contact the
local building department I /
i _ .
Sprinklers . I -
For ceilings without rigid bracing, sprinkler head penetrations shall have a 2 inch oversize ring, sleeve or adapter through the ceiling tile to allow free movement of at _ --
least 1 inch in all horizontal directions. Flexible head design that can accommodate — r t 1
1 inch free movement shall be permitted as an alternate. Souce ASCE 7 -02 9.6.2.6.2.2.itam a I Flange
Gap Pop
• — Design — Rivet
NORTHWEST WALL a CEILING BUREAU • SUSPENSION SYSTEMS FOR ACOUSTICAL LAY -IN CEILINGS
•
•
GLOSSARY FOR THIS DOCUMENT (regional terminology may vary)
CLOSURE ANGLES HANGER WIRE PLENUM
Wall molding that surrounds the perim- 10 or 12 gage soft annealed wire used as The space above a suspended ceiling.
eter of the suspension system and ceiling primary support for the grid system. Also
tiles. called suspension wires. SLACK WIRE
A 12 gage wire that is not tight or taut.
CROSS TEES LATERAL FORCE BRACING
The cross member that interlock with the The bracing method used to prevent ceil- SPREADER or SPACER BAR
main beams, also known as cross run- ing uplift or restrict lateral movement dur- A bar with notches to prevent the sus -
ners or cross T -bars. ing a seismic event. Lateral force bracing pension system from separating, also
consists of vertical struts and splay wires. called a stabilizer bar.
DIFFUSER
A circular or rectangular metal grill used MAIN BEAM SPLAY WIRES
for the passage of air from a ducted The primary suspension member sup - Wires installed at an angle rather than
system. ported by hanger wires, also known as Perpendicular to the grid.
the main runner, carrying tee, carrying
ESSENTIAL SERVICE BUILDINGS
STRUTS • runner or mains. The rigid vertical member used in lateral i
Any buildings designed to be used by 9�
public agencies as a fire station, MOLDING force bracing of the suspension system.
police station, emergency operations A light gauge metal angel or channel Also known as compression posts,
center, State Patrol office, sheriff's fastened to the wall or partition to seismic pods, seismic struts. Common
office, or emergency communication support the perimeter of an acoustical materials are electrical conduit (EMT),
dispatch center. tile or ceiling. metal studs or proprietary products.
GRID PERIMETER WIRES
The main beams and cross tees of the Hanger wires placed within eight inches
suspension system. of the surrounding walls.
The NWCB has been serving the construction
industry for over forty years. It is recognized
as a technical authority, educational body and
Nspokes person for the wall and ceiling industry.
It provides services to architects and the con -
struction community on all matters relating to the
NWCB - Oregon diversified wall and ceiling industry.
Phone: (503) 295 -0333 As the industry's development and coordination
Fax: (503) 295 -2733 organization, the NWCB saw the need to estab-
1032 NE 65th St, lish a document to provide clarification and the
Seattle, WA 98115 B.C. Wall and Ceiling Association Intent of NEHRP (National Earthquake Hazards
Phone: (604) 597 -7180 Reduction Program) an agency of FEMA (Federal
Phone (206) 524 - 4243 Fax: (604) 597 -7208 Emergency Management Agency). It is meant to
Fax (206) 524 - 4136 serve as a set of recommendations and is not
Toll Free (800) 524 - 4215 Alberta Wall and Ceiling Bureau intended for any specific construction project.
inioOnwcb.org Phone: (403) 250 -7045 The NWCB makes no express or implied warranty
www.nwcb.org Fax: (403) 291 -9515 or guarantee.
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