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Home My WebLink AboutENGINEER LETTER - 23-00710 - 433 W 2nd S - Solar Panels___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com To: BlueRavenSolar 1403NorthResearchWay,BuildingJ Orem,UT.84097 Subject: CertificationLetter SnowResidence 433W2ndS Rexburg,ID.83440 ToWhomItMayConcern, DesignCriteria: භ ApplicableCodes=2015IBC/IRC,ASCE7Ͳ10 භ RoofDeadLoad=7psf(MP1) භ RoofLiveLoad=20psf භ WindSpeed=115mph(Vult),ExposureC,RiskCategoryII භ භ Sincerely, BrandonLittle,P.E. ProjectEngineer October4,2023 Theroofstructureof(MP1)consistsofcompositionshingleonroofplywoodthatissupportedbypreͲmanufacturedtrussesthat arespacedat@24"o.c..Thetopchords,slopedat16degrees,are2x4sections,thebottomchordsare2x4sectionsandtheweb membersare2x4sections.Thetrussmembersareconnectedbysteelgussetplates.Themaxunsupportedprojectedhorizontal topchordspanisapproximately6'Ͳ0''. Theexistingroofframingsystemof(MP1)isjudgedtobeadequatetowithstandtheloadingimposedbytheinstallationofthe solarpanels.Noreinforcementisnecessary. GroundSnowLoad=50psfͲRoofSnowLoad=35psf Thespacingofthesolarstandoffsshouldbekeptat48"o.c.forlandscapeand48"o.c.forportraitorientation,withastaggered patterntoensureproperdistributionofloads. AjobsiteobservationoftheconditionoftheexistingframingsystemwasperformedbyanauditteamofBlueRavenSolarasa requestfromDomusStructuralEngineering.Allreviewisbasedontheseobservationsandthedesigncriterialistedbelowand onlydeemedvalidifprovidedinformationistrueandaccurate. Ontheabovereferencedproject,theroofstructuralframinghasbeenreviewedforadditionalloadingduetotheinstallationof thesolarPVadditiontotheroof.Thestructuralreviewonlyappliestothesectionoftheroofthatisdirectlysupportingthesolar PVsystemanditssupportingelements.Theobservedroofframingisdescribedbelow.Iffieldconditionsdiffer,contractorto notifyengineerpriortostartingconstruction. Thescopeofthisreportisstrictlylimitedtoanevaluationofthefastenerattachment,underlyingframingandsupporting structureonly.Theattachmentstotheexistingstructurearerequiredtobeinastaggeredpatterntoensureproperdistribution ofloading.Allpanels,rackingandhardwareshallbeinstalledpermanufacturerspecificationsandwithinspecifieddesign limitations.Allwaterproofingshallbeprovidedbythemanufacturer.DomusStructuralEngineeringassumesnoresponsibility formisuseorimproperinstallationofthesolarPVpanelsorracking. Pleasecontactmewithanyfurtherquestionsorconcernsregardingthisproject. Attachment:1Ͳ5/16dia.lagscrewwith2.5inchmin.embedment depth,atspacingshownabove. Snow Rexburg ID 1 Brandon R. Little Digitally signed by Brandon R. Little Date: 2023.10.04 11:38:17 -06'00' ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com 50.0 psf (ASCE7 - Eq 7-1) 1 (ASCE7 - Table 7-2) 1 (ASCE7 - Table 7-3) 1 35.0 psf (ASCE7 - Eq 7-2) 1 35.0 psf 3.12 psf 3.0 psf 4.00 ft 6.08 ft 24.33 sft 73 lb 4.00 2.00 0.73 0.00 (Ceiling Not Vaulted) 0.27 7.0 psf 7.3 psf Gravity Loading PV System Weight Weight of PV System (Per Blue Raven Solar) X Standoff Spacing = Y Standoff Spacing = Note: PV standoffs are staggered to ensure proper distribution of loading 2x4 Top Chords @ 24"o.c. I = Importance Factor = Cs = Slope Factor = Standoff Tributary Area = ps = Cspf ps = Sloped Roof Snow Load = pf = Flat Roof Snow Load = DL Adjusted to 16 Degree Slope Roof Snow Load Calculations pg = Ground Snow Load = Ce = Exposure Factor = pf = 0.7 Ce Ct I pg Ct = Thermal Factor = Roof Live Load = 20 psf Roof Plywood Roof Dead Load (MP1) Composition Shingle Note: Roof live load is removed in area's covered by PV array. DL Adjusted to 16 Degree Slope Point Loads of Standoffs Miscellaneous Vaulted Ceiling Total Roof DL (MP1) PV Dead Load = 3 psf (Per Blue Raven Solar) Snow Rexburg ID 2 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com 115 mph C Hip/Gable 16 degrees 20 ft 21.3 ft (Eq. 30.3-1) 0.9 (Table 30.3-1) 1 (Fig. 26.8-1) 0.85 (Table 26.6-1) 115 mph (Fig. 26.5-1A) II (Table 1.5-1) qh = 25.90 15.54 Zone 1 Zone 2 Zone 3 Positive GCp = -0.85 -1.52 -2.42 0.43 (Fig. 30.4-1) Uplift Pressure = -13.20 psf -23.67 psf -37.59 psf 11.1 psf X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 6.08 3.041666667 3.04166667 Tributary Area = 24.33 12.17 8.11 Dead Load on Attachment=73.00 36.50 24.33 Footing Uplift (0.6D+0.6W)= -277 lb -266 lb -290 lb Zone 1 Zone 2 Zone 3 Positive GCp = -0.85 -1.52 -2.42 0.43 (Fig. 30.4-1) Uplift Pressure = -13.20 psf -23.67 psf -37.59 psf 10.0 psf (Minimum) X Standoff Spacing = 4.00 4.00 2.67 Y Standoff Spacing = 3.50 1.75 1.75 Tributary Area = 14.00 7.00 4.67 Dead Load on Attachment=42.00 21.00 14.00 Footing Uplift (0.6D+0.6W) = -160 lb -153 lb -167 lb -290 lb 450 lb Therefore, OK Fastener =1 - 5/16" dia. lag Number of Fasteners = 1 Embedment Depth = 2.5 Pullout Capacity Per Inch = 250 lb Fastener Capacity = 625 lb w/ F.S. of 1.5 & DOL of 1.6= 667 lb Therefore, OK Wind Calculations Maximum Design Uplift = Standoff Uplift Capacity = 450 lb capacity > 290 lb demand Fastener Capacity Check Standoff Uplift Check Kz (Exposure Coefficient) = Kzt (topographic factor) = Kd (Wind Directionality Factor) = V (Design Wind Speed) = Risk Category = qh = 0.00256 * Kz * Kzt * Kd * V^2 Wind Pressure P = qh*G*Cn Exposure Category PerASCE7Ͳ10ComponentsandCladding Mean Roof Height Roof Slope 667.2 lb capacity > 290 lb demand 0.6 * qh = Standoff Uplift Calculations-Landscape Input Variables Wind Speed Effective Wind Area Design Wind Pressure Calculations Roof Shape Standoff Uplift Calculations-Portrait Snow Rexburg ID 3 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com (MP1)PASS Dead Load 7.3 psf PV Load 3.1 psf Snow Load 35.0 psf Governing Load Combo = DL + SL Total Load 45.4 psf Fb (psi) = f'b 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 (wL^2) / 8 = 408.6269 ft# = 4903.523 in# Actual Bending Stress = (Maximum Moment) / S = 1601.2 psi L/180 (E = 1600000 psi Per NDS) = 0.4 in Deflection Criteria Based on = (w*L^4) / (185*E*I) = = L/559 > L/180 Therefore OK Allowed Deflection (Live Load) =L/240 0.3 in (w*L^4) / (185*E*I) L/728 > L/240 Therefore OK Member Area = Fv (psi) = 180 psi (NDS Table 4A) Allowed Shear = Fv * A = Max Shear (V) = w * L / 2 = 272 lb Framing Check 5.3 in^2 Check Shear w = 91 plf 2x4 Top Chords @ 24"o.c. Member Span = 6' - 0" 945 lb Allowed > Actual -- 28.9% Stressed -- Therefore, OK DF#2 Member Spacing @ 24"o.c. Maximum Moment = Check Deflection I (in^4) 5.36 Lumber Sp/Gr Actual Deflection (Live Load) = Allowed Deflection (Total Load) = Actual Deflection (Total Load) = Allowed > Actual -- 89.7% Stressed -- Therefore, OK Member Properties Member Size 2x4 S (in^3) 3.06 0.099 in Continuous Span 0.129 in Check Bending Stress (True Dimensions) Snow Rexburg ID 4 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com Level Area Weight (psf) Weight (lb) Roof 1199 sf 7.3 psf 8734 lb Ceiling 1199 sf 6.0 psf 7196 lb Wood Siding 100 ft 5.0 psf 2000 lb (8'-0" Wall Height) Int. Walls 100 ft 6.4 psf 2560 lb 20491 lb 3.0 psf 192 sf 576 lb 2049 lb 576 lb 2.8% Lateral Check 2049 lb > 576 lb, Therefore OK Existing Weight of Effected Building Existing Weight of Effected Building Proposed Weight of PV System Weight of PV System (Per Blue Raven Solar) Approx. Area of Proposed PV System Approximate Total Weight of PV System 10% Comparison 10% of Existing Building Weight (Allowed) Approximate Weight of PV System (Actual) Percent Increase Snow Rexburg ID 5 ___________________________________________________________________________________________ Domus Structural Engineering, LLC P.O. Box 560 Broomfield, CO 80038 530-864-7055 projects@domusstruc.com Appendix A: General Notes GENERAL Ɣ The contractor shall verify all dimensions, property setbacks, AHJ/HOA CC&R's, elevations and site conditions before starting work and shall notify Domus Structural Engineering, LLC of any discrepancies. Ɣ All report conclusions represent Domus Structural Engineering, LLC's best professional judgment based upon industry standards. Ɣ Resolve any conflicts on the drawings with Domus Structural Engineering, LLC before proceeding with construction. Ɣ The design criteria used for this project & listed on the first page of the report is based on the engineers best judgement and/or provided by the ATC council. AHJ specific requests may differ. Please contact our team if the design criteria needs to be modified. Ɣ A site visit was not physically conducted by Domus Structural Engineering, LLC. The accompanying calculations and certification are provided with the understanding that the site building and construction standards meet an acceptable level of industry standards. It shall be the contractors responsibility to identify any irregularities such as inconsistent framing conditions, water damage, fire damage, cracked, split or noticeably deflecting framing members. Ɣ Domus Structural Engineering, LLC is not responsible for enforcing safety measures or regulations. The contractor shall design, construct, and maintain all safety devices including shoring and bracing, and shall be solely responsible for conforming to all local, state and federal safety and health standards, laws and regulations. The contractor shall take necessary precautions to maintain and insure the integrity of the structure during construction. If a lawsuit is filed by one of the contractor's or subcontractor's employees, or any one else, the contractor will indemnify, defend and hold the owner and Domus Structural Engineering, LLC harmless of any and all such claims. Ɣ Any and all waterproofing shall be provided by the contractor. Domus Structural Engineering, LLC is not responsible for waterproofing. Ɣ All hardware shall be installed per manufacturer specifications and within specified design limitations. Domus Structural Engineering, LLC assumes no responsibility for incorrectly installed hardware or hardware installed outside of the manfacturer specifications. USER RELIANCE Ɣ Domus Structural Engineering, LLC was engaged by Blue Raven Solar (Client) to perform this assessment. This report and the information therein, are for the exclusive use of the Client. This report has no other purpose and shall not be relied upon, or used, by any other person or entity without the written consent of Dous Structural Engineering, LLC. Third parties that obtain this report, or the information within shall have no rights of recourse or recovery against Domus Structural Engineering, LLC, it’s officers or employees. ROOF MOUNTED ARRAYS Ɣ If an analysis of a supporting stucture is included in our scope of work, the structural assessment only applies to the section of the roof that is directly supporting the proposed solar PV system. Ɣ No structural members can be cut for conduit, etc., unless specifically shown. Obtain prior written approval for installation of any additional conduit, etc. Ɣ It is assumed that a standard quality of construction care was used to construct the original building. It shall be the contractors responsibility to field verify any and all framing member supporting the proposed PV array are in adequate condition. The contractor shall field inspect for sub-standard construction means, signs of dry rot, mold, fire damage, etc. and notify engineer if any compromised material is found on site prior to starting construction. Ɣ It is assumed that there have been no additional loads (HVAC or MEP equipment, additional layers of roofing, etc) added to the building over the course of the structures histroy. The contractor and/or client shall verify this with the property owner and notify Domus Structural Engineering, LLC if additional load has been added to the structure already. Ɣ Flexible utility connections must be used at any building seismic joint. Ɣ Care should be taken to ensure that PV arrays do not preclude drainage of rain water. Ɣ Unless otherwise noted, construction material shall be evenly distributed if placed on framed floors or roofs. Loads shall not exceed the allowable loading for the supporting members and their connections. Ɣ All lags or wood screws at the roof shall be stainless steel and installed withing the middle 1/3 of the dimensional width of the framing members. Ɣ All fasteners shall be a minimum of 6" away from any truss panel or hinge joints, truss plates and/or member ends. Field verify location of fasteners prior to starting construction. All fasteners shall be pre-drilled to avoid splitting existing lumber. Ɣ Domus Structural Engineering, LLC is not responsible for downslope effects of snow shedding or sliding off of the PV array nor any damage to downslope decks, roofs, walkways, landscaping, automobiles, pets, people, etc.. If snow guards are requested by the customer, notify Domus Structural Engineering, LLC. Snow Rexburg ID 6