The URL can be used to link to this page

Report (4) Domus EEI RECEIVED Domus Structural Engineering, LLC TR U C T U R A P.O. Box 6986 �+� OCT 13 2021 Broomfield, CO 80021 I NEER UNG 11C. 530-864-7055 CITY OF TIGARD Domusstructural@gmail.com 3UILDING DIVISION August 31,2021 Z) L// �50 To: Ion Solar u < D-5u—) 5 e 4801 N.University Ave.Suite 900 / tJ l•�l Provo,UT.84604 Subject: Certification Letter Sandburg Residence 14590 SW 92nd Ave Tigard,OR.97224 To Whom It May Concern, A jobsite observation of the condition of the existing framing system was performed by an audit team of Ion Solar as a request from Domus Structural Engineering.All review is based on these observations and the design criteria listed below and only deemed valid if provided information is true and accurate. On the above referenced project,the roof structural framing has been reviewed for additional loading due to the installation of the solar PV addition to the roof.The structural review only applies to the section of the roof that is directly supporting the solar PV system and its supporting elements.The observed roof framing is described below.If field conditions differ,contractor to notify engineer prior to starting construction. The roof structures of(RSI&2)consist of composition shingle on roof plywood that is supported by pre-manufactured trusses that are spaced at @ 24"o.c..The top chords,sloped at 6 degrees,are 2x4 sections,the bottom chords are 2x4 sections and the web members are 2x4 sections.The truss members are connected by steel gusset plates.The max unsupported projected horizontal top chord span is approximately 6'-6". The existing roof framing systems of(RSI&2)are judged to be adequate to withstand the loading imposed by the installation of the solar panels.No reinforcement is necessary. The spacing of the solar standoffs should be kept at 48"o.c.for landscape and 48"o.c.for portrait orientation,with a staggered pattern to ensure proper distribution of loads. The scope of this report is strictly limited to an evaluation of the fastener attachment, underlying framing and supporting structure only.The attachment's to the existing structure are required to be in a staggered pattern to ensure proper distribution of loading.All panels,racking and hardware shall be installed per manufacturer specifications and within specified design limitations.All waterproofing shall be provided by the manufacturer. Domus Structural Engineering assumes no responsibility for misuse or improper installation of the solar PV panels or racking. D PROFES Design Criteria: �� S �5 NGINEp /� • Applicable Codes=2019 OSISC&2017 ORSC,ASCE 7-16 �� 29 • Roof Dead Load=7 psf(RS1&2) 345PE r • Roof Live Load=20 psf • Wind Speed=96 mph(Vult),Exposure C • Ground Snow Load=25 psf - Roof Snow Load=20 psf OREGO • Attachment:1-5/16 dia.lag screw with 2.5 inch min.embedment depth,at spacing shown above. y6,201 �� N A. C ALJ Digitally signed Please contact me with any further questions or concerns regarding this project. by John Calvert Date:2021.10.06 Sincerely, Exp:12/31/21 08:06:22-06'00' John Calvert,P.E. Project Engineer Sandburg Residence Tigard OR.xlsm 1 T Domus Structural Engineering, LLC lS P.O. Box 6986 S 'I' H t t; "I' I R A I. Broomfield, CO 80021 530-864-7055 `," 6 T N 1` 117. 1t i N 1, L C: Domusstructural@gmail.com Gravity Loading Roof Snow Load Calculations p9=Ground Snow Load= 25 psf pf=0.7 Ce Ct I p9 (ASCE7-Eq 7-1) Ce=Exposure Factor= 1 (ASCE7-Table 7-2) Ct=Thermal Factor= 1 (ASCE7-Table 7-3) 1= Importance Factor= 1 pf=Flat Roof Snow Load= 20.0 psf PS=CSpf (ASCE7-Eq 7-2) Cs=Slope Factor= 1 ps=Sloped Roof Snow Load= 20.0 psf PV Dead Load=3 psf(Per Ion Solar) DL Adjusted to 6 Degree Slope 3.02 psf PV System Weight Weight of PV System(Per Ion Solar) 3.0 psf X Standoff Spacing= 4.00 ft Y Standoff Spacing= 3.00 ft Standoff Tributary Area= 12 00 sft Point Loads of Standoffs 36 Ib Note: PV standoffs are staggered to ensure proper distribution cf loading Roof Live Load=20 psf Note: Roof live load is removed in area's covered by PV array. Roof Dead Load(RS1&2) Composition Shingle 4.00 Roof Plywood 2.00 2x4 Top Chords @ 24"o.c. 0.73 Vaulted Ceiling 0.00 (Ceiling Not Vaulted) Miscellaneous 0.27 Total Roof DL(RS1&2) 7.0 psf DL Adjusted to 6 Degree Slope 7.0 psf Sandbura Residence Tigard OR.xlsm 2 1J�+o m u s Domus Structural Engineering,LLC 5 T R U C T i' R A L P.O.Box 6986 Broomfield,CO 80021 N Ci 1 N E 1: R T N ti 1. 1. C; 530-864-7055 Domusstructural@gmail.com Wind Calculations Per ASCE 7-16 Components and Cladding Input Variables Wind Speed 96 mph Exposure Category C Roof Shape Gable Roof Roof Slope 6 degrees Mean Roof Height 20 ft Effective Wind Area 20.1 ft Ground Elevation Off Design Wind Pressure Calculations qh=0.00256*Kz*Kzt*Kd*Ke*V^2 (Eq.26.10-1) Kz(Exposure Coefficient)=0.90 (Table 30.3-1) Kzt(topographic factor)= 1.00 (Fig.26.8-1) Kd(Wind Directionality Factor)= 0.85 (Table 26.6-1) Ke(Ground Elevation Factor)= 1.00 V(Design Wind Speed)=96 mph (Fig.26.5-1 A) Risk Category=II (Table 1.5-1) ch= 18.09 Standoff Uplift Calculations-Portrait Zone 1 Zone 2 Zone 3 Positive Ya= 0.77 0.77 0.80 0.77 GCp= -2.00 -2.89 -3.60 0.52 (Fig.30.3) Uplift Pressure= -28.0 psf -40.4 psf -52.1 psf 7.2 psf (Eq.29.4-7) ASD Uplift Pressure= -16.8 psf -24.2 psf -31.3 psf 9.6 psf X Standoff Spacing= 4.00 4.00 2.67 Y Standoff Spacing= 3.00 3 3 Tributary Area= 12.00 12.00 8.00 Dead Load on attachment= 3611b 3611b 241b Footing Uplift(0.6D+0.6W)_ -180 lb -2691b -2361b Standoff Uplift Calculations-Landscape Zone 1 Zone 2 Zone 3 Positive Ya= 0.80 0.80 0.80 0.80 GCp= -2.00 -3.00 -3.60 0.58 (Fig.30.3) Uplift Pressure= -28.9 psf -43.4 psf -52.1 psf 8.3 psf (Eq.29.4-7) ASD Uplift Pressure(0.6W)= -17.4 psf -26.0 psf -31.3 psf 9.6 psf X Standoff Spacing= 4.00 4.00 2.67 Y Standoff Spacing= 1.67 1.67 1.67 Tributary Area= 6.68 6.68 4.45 Dead Load on attachment= 20.04 20.04 13.36 Footing Uplift(0.6D+0.6W)= -104 lb -162 Ib -131 Ib Standoff Uplift Check Maximum Design Uplift=-269 Ib Standoff Uplift Capacity =450 Ib 450 Ib capacity>269 Ib demand Therefore,OK Fastener Capacity Check Fastener=1 5 l da iaa Number of Fasteners=1 Embedment Depth=2.5 Pullout Capacity Per Inch= 2501b Fastener Capacity=62511b w/F.S.of 1.5&DOL of 1.6=667 Ib 667.2 Ib capacity>269 Ib demand Therefore,OK Sandburg Residence Tigard OR.xlsm 3 Domus Structural Engineering, LLC Do1T � P.O. Box 6986 S i, K T -i, T; R A i Broomfield, CO 80021 530-864-7055 EN G T "ti T= F R T 1\ C', T. T. C: Domusstructural@gmail.com Framing Check (RSI&2) PASS w=60plf Dead Load 7.0 psf PV Load 3.0 psf Snow Load 20.0 psf 2x4 Top Chords @ 24"o.c. O Governing Load Combo=DL+SL Member Span=6'-6" Total Load 30.1 psf Member Properties Member Size S(in"3) 1(in"4) Lumber Sp/Gr Member Spacing 2x4 3.06 5.36 DF#2 @ 24"o.c. Check Bending Stress Fb(psi)= fb x Cd x Cf x Cr (NDS Table 4.3.1) 900 x 1.15 x 1.5 x 1.15 Allowed Bending Stress= 1785.3 psi Maximum Moment = (wL^2)/8 = 317.4568 ft# = 3809.482 in# Actual Bending Stress=(Maximum Moment)/S = 1244 psi Allowed>Actual--69.7%Stressed -- Therefore,OK Check Deflection Allowed Deflection(Total Load) _ L 1 bu (E= 1600000 psi Per NDS) = 0.433 in Deflection Criteria Based on = Continuous Span Actual Deflection(Total Load) _ (w*L"4)/(185*E*I) = 0.117 in = U667 > L/180 Therefore OK Allowed Deflection(Live Load) = L/240 0.325 in Actual Deflection(Live Load) _ (w*L"4)/(185*E*I) 0.078 in L/1000 > U240 Therefore OK Check Shear Member Area= 5.3 in^2 Fv(psi)= 180 psi (NDS Table 4A) Allowed Shear = Fv*A = 945 Ib Max Shear(V)=w*L/2 = 195 Ib Allowed>Actual--20.7%Stressed -- Therefore,OK Sandhura Residence Tigard OR Asm 4 Domus Structural Engineering, LLC f) o [:Ts P.O. Box 6986 .1, R l C T I.r RA 1, Broomfield, CO 80021 530-864-7055 E N G T 1 F T? R T 1\ G► T. T. Ctateral Check Domusstructural@gmail.com Existing Weight of Effected Building Level Area Weight(psf) Weight(lb) Roof 3139 sf 7.0 psf 22094 Ib Ceiling 3139 sf 6.0 psf 18834 Ib Wood Siding 100 ft 5.0 psf 2000 Ib (8'-0"Wall Height) Int.Walls 100 ft 6.4 psf 2560 Ib Existing Weight of Effected Building 45488 Ib Proposed Weight of PV System Weight of PV System(Per Ion Solar) 3.0 psf Approx.Area of Proposed PV System 421 sf Approximate Total Weight of PV System 1263 Ib 10%Comparison 10%of Existing Building Weight(Allowed) 4549 Ib Approximate Weight of PV System(Actual) 1263 Ib Percent Increase 2.8% 4549 Ib>1263 Ib,Therefore OK Sandbura Residence Tigard OR.xlsm 5