The URL can be used to link to this page

Home My WebLink AboutPE Calcs_Conroy, Julieprojects@evengineersnet.com http://www.evengineersnet.com 276-220-0064 12/10/2020 RE: Structural Certification for Installation of Residential Solar Conroy, Julie:53 Barnboard Ln, West Yarmouth, MA 02673 Attn: To Whom It May Concern Design Criteria Code 2015 International Building Code (ASCE 7-10) Risk category II Wind Load (component and Cladding) Roof Dead Load Dr 10 psf V 141 mph PV Dead Load DPV 3 psf Exposure B Roof Live Load Lr 20 psf Ground Snow S 30 psf If you have any questions on the above, please do not hesitate to call. Sincerely, Vincent Mwumvaneza, P.E. EV Engineering, LLC projects@evengineersnet.com http://www.evengineersnet.com This Letter is for the existing roof framing which supports the new PV modules as well as the attachment of the PV system to existing roof framing. From the field observation report, the roof is made of Composition shingle roofing over roof plywood supported by 2X10 Rafters at 16 inches. The slope of the roof was approximated to be 43 degrees and having an allowable maximum beam span of 10 feet between supports. After review of the field observation data and based on our structural capacity calculation, the existing roof framing has been determined to be adequate to support the imposed loads without structural upgrades. Capacity calculations were done in accordance with applicable building codes. 1/1 projects@evengineersnet.com http://www.evengineersnet.com 276-220-0064 Structural Letter for PV Installation 12/10/2020 Job Address:53 Barnboard Ln West Yarmouth, MA 02673 Job Name:Conroy, Julie Job Number:201210CJ Scope of Work Table of Content Sheet 1 Cover2Attachment checks3Snow and Roof Framing Check 4 Seismic Check and Scope of work Engineering Calculations Summary Code 2015 International Building Code (ASCE 7-10) Risk category II Roof Dead Load Dr 10 psf PV Dead Load DPV 3 psf Roof Live Load Lr 20 psf Ground Snow S 30 psf Wind Load (component and Cladding) V 141 mph Exposure B References 1 International Residential Code, 2015 2 NDS for Wood Construction Sincerely, Vincent Mwumvaneza, P.E. EV Engineering, LLC projects@evengineersnet.com http://www.evengineersnet.com This Letter is for the existing roof framing which supports the new PV modules as well as the attachment of the PV system to existing roof framing. All PV mounting equipment shall be designed and installed per manufacturer's approved installation specifications. 1/1 projects@evengineersnet.com http://www.evengineersnet.com 276-220-0064 Wind Load Cont. ASCE 7-10 Table 1.5-1 141 mph ASCE 7-10 Figure 26.5-1A ASCE 7-10 Sec 26.7.2 ASCE 7-10 Sec 26.7.3 ASCE 7-10 Sec 26.8.2 23.0 ft 18.0 ft 22.0 ft 43.0 Degrees ASCE 7-10 Figure 30.5-1 40.0 ft 60.0 ft 4.00 ft ASCE 7-10 Figure 30.5-1 Uplift (0.6W)Zone 1 (psf) Zone 2 (psf) Zone 3 (psf) Pnet30= -29.7 -35.8 -35.8 Figure 30.5-1 Pnet = 0.6 x λ x KZT x Pnet30)= 17.84 21.49 21.49 Equation 30.5-1 Downpressure (0.6W)Zone 1 (psf) Zone 2 (psf) Zone 3 (psf) Pnet30= 32.5 32.5 32.5 Figure 30.5-1 Pnet = 0.6 x λ x KZT x Pnet30)= 19.52 19.52 19.52 Equation 30.5-1 Rafter Attachments: 0.6D+0.6W (CD=1.6) Lag Screw Connection Attachement max. spcaing=4 ft 5/16" Lag Screw Withdrawl Value=266 lb/in Table 12.2A - NDS Lag Screw Penetration=2.5 in DFL assumed Prying Coefficient 1.4 Allowable Capacity with CD= 760 lb 0.6D+0.6W Dpv+0.6W Zone Trib Width Area (ft) Uplift (lbs) Down (lbs) 1 4 11.0 176.5 247.7 2 4 11.0 216.6 247.7 3 3 8.3 162.5 185.8 Max=216.6 <760 CONNECTION IS OK 1. Pv seismic dead weight is negligible to result in significant seismic uplif, therefore the wind uplift governs 2. Embedment is measured from the top of the framing member to the tapered tip of a lag screw. Embedment in sheading or other material does not count. Topographic Factor, KZT = 1.00 Ridge Height = Eave Height = Mean Roof Height, h = Pitch = Adjustment Factor, λ =1 Buidling Width = Building Length = a = Where a: 10% of least horizontal dimension or 0.4h, whichever is smaller, but not less than 4% of least horizontal dimension or 3ft (0.9m) Exposure =B II B 1/1 projects@evengineersnet.com http://www.evengineersnet.com 276-220-0064 Vertical Load Resisting System Design Roof Framing Rafters 30 psf ASCE 7-10 , Section 7.2 pf = 21 psf 0.9 ASCE 7-10 , Table 7-2 pfmin. = 25.0 psf Ct =1.1 ASCE 7-10 , Table 7-3 ps = 25 psf 33.3 plf Is =1.0 ASCE 7-10 , Table 1.5-1 Consevatively (Cs=1) Max Length, L =10 ft (Beam maximum Allowable Horizontal Span) Tributary Width, WT =16 in Dr =10 psf 13.33 plf PvDL =3 psf 4 plf Load Case: DL+0.6W (CD=1.6) Pnet+ Ppvcos(θ)+PDL=43.4 plf Max Moment, Mu =542 lb-ft Conservatively Pv max Shear 247.7 lbs Max Shear, Vu=wL/2+Pv Point Load =334 lbs Load Case: DL+0.75(0.6W+S) (CD=1.6) 0.75(Pnet+Ps)+ Ppvcos(θ)+PDL=61 plf Mdown=760 lb-ft Mallowable = Sx x Fb' (wind)=3247 lb-ft >760 lb-ft OK Load Case: DL+S (CD=1.15) Ps+ Ppvcos(θ)+PDL=50 plf Mdown=620 lb-ft Mallowable = Sx x Fb' (wind)=2334 lb-ft >620 lb-ft OK Max Shear, Vu=wL/2+Pv Point Load =334 lbs Member Capacity DF-L No.2 2X10 CL CF Ci Cr KF φ λ Fb =900 psi 1.0 1.1 1.0 1.15 2.54 0.85 0.8 1139 psi Fv =180 psi N/A N/A 1.0 N/A 2.88 0.75 0.8 180 psi E =1600000 psi N/A N/A 1.0 N/A N/A N/A N/A 1600000 psi Emin =580000 psi N/A N/A 1.0 N/A 1.76 0.85 N/A 580000 psi Depth, d =9.25 in Width, b =1.5 in Cross-Sectonal Area, A = 13.875 in2 Moment of Inertia, Ixx =98.9316 in4 Section Modulus, Sxx =21.3906 in3 Allowable Moment, Mall = Fb'Sxx =2029.4 lb-ft DCR=Mu/Mall =0.26 < 1 Satisfactory Allowable Shear, Vall = 2/3Fv'A =1665.0 lb DCR=Vu/Vall =0.20 < 1 Satisfactory Design Value Adjusted Value 1/1 projects@evengineersnet.com http://www.evengineersnet.com 276-220-0064 Siesmic Loads Check Roof Dead Load 10 psf % or Roof with Pv 28% Dpv and Racking 3 psf Averarage Total Dead Load 10.8 psf Increase in Dead Load 3.4%OK Limits of Scope of Work and Liability The increase in seismic Dead weight as a result of the solar system is less than 10% of the existing structure and therefore no further seismic analysis is required. We have based our structural capacity determination on information in pictures and a drawing set titled PV plans - Conroy, Julie. The analysis was according to applicable building codes, professional engineering and design experience, opinions and judgments. The calculations produced for this dwelling's assessment are only for the proposed solar panel installation referenced in the stamped plan set and were made according to generally recognized structural analysis standards and procedures. 1/1