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Home My WebLink AboutLA205377 - Approved - Stamped Engineering Letter1555 Freedom Blvd #REF! Provo, UT 84604 Phone: 844.357.2258 Email: solarpermits@solcius.com Solcius Job # P-243559-22 Prepared by Arlo Hulick August 15, 2022 License Expires 6.30.24 16549 Gunflint Trail Lakeville, MN I have examined the existing Truss framing with 2 x 4 rafters @ 24 inches on center spanning 5 feet that support the roof of this structure. I have performed structural calculations finding the framing to be adequate for gravity and uplift loads applied to the roof by the solar panels, including snow loads applied as point loads to the roof framing, where applicable. The attachments and railing are also adequate without reinforcement for the loads imposed when installed with the attachment spacing shown in the drawings. We recommend the attachments be staggered as shown in the drawings to avoid overloading the rafters. Solar Panel Addition for: Structural Analysis Report Cerna Residence Structural Calculations Rev 7.00 1/6/17 Table of Contents General Notes 3 Project Data 4 Dead Loads 5 Live Loads 6 Gravity Load Increase 6 Lateral Force Increase 6 Solar Panel Support Frame 7 Wind uplift on Mounting System 7 Lateral Forces Analysis N/A Roof Framing Analysis 8 Snow Load Calculations 10 References Attachment Pull-out Capacity R-1 The following reference sheets are attached and inserted behind construction plans. •Solar Panel Characteristics •Mounting System Specifications •Rail Specifications Drawings Roof Plan PV-02 Attachment Spacing PV-05 Racking Elevation PV-08 Job # P-243559-22 Cerna Residence August 15, 2022 Structural Calculations Rev 7.00 1/6/17 Page 2 Job # P-243559-22 Cerna Residence August 15, 2022 General Notes 1) These structural calculations are not intended to be applicable for non-structural items including, but not limited to, electrical, waterproofing, or drainage. 2) All construction methods and materials shall comply with the building code listed in the design criteria. Structural Calculations Rev 7.00 1/6/17 Page 3 Job # P-243559-22 Cerna Residence August 15, 2022 Project Data Project Location Lakeville, MN Design Criteria: Building code:2020 Minnesota State Building Code Design Specifications:ASCE 7-16, NDS 2018, AISC 2016 Roof snow load on solar panel 50.0 psf See snow load calcs supplement Roof snow without solar panel 50.0 psf Risk category II Basic wind speed V 115 mph Wind exposure C Roof angle θ 21.0 deg. Roof zone 2 Interior component GCpi +/- 0.18 Seismic design criteria Existing residence Roof area 2912.0 sf Eave to ridge distance 17 ft Roof rise 4.6 :12 Ridge height 18.5 ft Eave height 12 ft Mean roof height hr 15.3 ft Roof structure:Truss Roof material:Asphalt Shingle Proposed PV system Solar panels:ZNShine ZXM6-NH120-370/M Solar panel rail system:EcoFasten ClickFit Mounting System:EcoFasten GF-1 Flashing w/L-Foot Attachment screws:(1) 4" x 5/16" lag screw Lateral analysis is based on percentage of weight added to main force resisting system and is independent of seismic force parameters. Per IEBC §1103.2 existing design does not require retrofitting if added weight is less than 10% of original weight. Structural Calculations Rev 7.00 1/6/17 Page 4 Job # P-243559-22 Cerna Residence August 15, 2022 Dead Loads PV System Panel wt 45.2 lbs Panel frame wt 5.2 lbs Conductor wt 3.0 lbs Total weight 53.4 lbs Width 40.87 in. Length 69.09 in. Panel area 19.6 sf Panel dead load 2.72 psf Roof Type wt Covering Asphalt Shingle 5.4 psf Sheathing 7/16" OSB (See Note)1.8 psf assumes weight of heavier Roof framing 1.0 psf plywood for purposes of Roof load 8.2 psf checking the framing Ceiling Joists 0.0 psf Mechanical, Insulation 0.0 psf Ceiling 5/8"gypsum 2.8 psf Ceiling load 2.8 psf Total roof and ceiling load 11.0 psf Floor Type wt Covering Carpet & pad 2.0 psf Underlayment 3/4" Plywood 2.5 psf Framing 10.0 psf Mechanical / Electrical 2.0 psf Ceiling 5/8" gypsum 2.8 psf Other 0.7 psf Floor dead load 20.0 psf Walls Type wt Covering 7/16" OSB 10.0 psf Sheathing 3/8" plywood 3.0 psf Insulation 1.0 psf Framing per 1' of rafter 1.1 psf Interior surface 5/8" gypsum 3.0 psf Wall dead load 18.1 psf Structural Calculations Rev 7.00 1/6/17 Page 5 Job # P-243559-22 Cerna Residence August 15, 2022 Live Loads Unbalanced roof snow load S 50.0 psf See snow load calculations Roof live load Lr 20.0 psf Cd = 1.25 Governing load 50.0 psf Snow load governs, based on max (load/Cd) Snow load on panel 50.0 psf See snow load calculations Gravity Load Increase Rafters Rafter length 17 ft. Rafter spacing 24 in. on center Roof area trib to rafter 34.0 sf Original roof load 279 lbs Dead load only Panel trib width to rafter 24 in. # Panels on rafter (portrait)2 # Panels on rafter (landscape)1 Panel area trib to rafter 29.8 sf Added weight 81 lbs % Load increase 29.1% IEBC §1103.1 Lateral Force Increase Roof trib area to MFRS 1456 sf Interior wall trib to MFRS 0 sf Floor trib area to MFRS 0 sf Interior wall weight 8 psf Wall trib area to MFRS 259 sf Interior wall wt to MFRS 0.0 kips Roof wt tributary to MFRS 16.0 kips Floor wt tributary to MFRS 0.0 kips Wall wt tributary to MFRS 4.7 kips Original wt to MFRS 20.7 kips # PV panels trib to MFRS 25.00 panels PV system weight 1.3 kips % weight increase 6.4% IEBC §1103.2Lateral force increase <10%, existing MFRS is O.K. FURTHER ANALYSIS REQUIRED (see page 8) Structural Calculations Rev 7.00 1/6/17 Page 6 Job # P-243559-22 Cerna Residence August 15, 2022 Solar Panel Support Frame Maximum span length 64 in Rail span 48 in The mounting system is adequate for the proposed fastener spacing. Wind uplift on Mounting System Governing Load Case:0.6D + 0.6W (ASD Load Case 7, ASCE 7-16 §2.4.1) Attachment spacing Sattach 48 in. Attachment spacing Sperp 33 in. Mounting point trib area Atrib 11.0 sf Atrib = Sattach Sperp Pressure Coeff. GCp (up)-2.5 psf ASCE 7-16 29.4.4, fig. 30.3-2C, zone 2r Array edge factor γE 1.5 ASCE 7-16 29.4.4 Pressure equal. factor γa 0.4 ASCE 7-16 fig. 29.4-8 Velocty Pressure Coeff. (qh)34.0 ASCE 7-16 29.4.4 Array trib area 174.2 sf = module area * # modules in array Mean roof height hr 15.3 ft Bldg ht adjust factor λ 1.00 N/A, used only in ASCE 7-10 Topographic factor Kzt 1.0 ASCE 7-16, Figure 26.8-1 Design wind pressure P -50.1 psf ASCE 7-16, Eqn. 29.4-7 Dead load 2.7 psf Wind load -50.1 psf Net Uplift (0.6D + 0.6W)28.4 psf (upward) Uplift on attachment Puplift 313 lbs Puplift = Net Uplift Atrib Attachment screws used: Use (1) 4" x 5/16" lag screw Min. embedment depth 3.25 inches Pull-out capacity per inch 582 lbs Pull-out capacity per manufacturer, see page R-1 Tensile capacity 1890 lbs Attachment spacing is O.K. Attachment is O.K. EcoFasten, Exp. C, 115 mph, zone 2, ECO50 psf snow,see allowable rail span chart. Structural Calculations Rev 7.00 1/6/17 Page 7 Existing Rafter Analysis Beam properties, size, spacing and span Douglas fir-larch #1 & BTR assumed Rafter span L 5.00 feet Rafter spacing 24 inches Rafter size 2 x 4 Additional point loads may be considered - see Section modulus 3.06 in3 next sheet, "Point Loads for Rafter Analysis" Allowable stress Fb 1200 psi Size factor CF 1.50 Repetitive use factor Cr 1.15 Cd shown for individual load cases below All other adjustment factors = 1 Loads on roof and solar panels Roof dead load 8.2 psf Panel dead load 2.72 psf Roof live load 20.0 psf Wind uplift -46.3 psf Wind downforce 16.0 psf Snow load on panels 50.0 psf Assumes slippery panels Snow load on roof, no panels 50.0 psf Assumes non-slippery roof (except metal roofs) Loads prior to installation:w (plf)Cd w/Cd Point loads from solar not applied prior to install D + Lr 56.4 1.25 45.1 45.1 0.6 D + 0.6 W up -45.7 1.60 -28.6 28.58162 D + 0.6 W dn 35.6 1.60 22.3 22.3 D + S 116.4 1.15 101.2 101.2 D + S 116.4 1.15 101.2 Governing load case is determined by max w/Cd Total load before install:582 lbs =wL Rafter end conditions Continuous at one end Moment at center span 291 ft lbs = wL^2 / 10 Check member for adequacy prior to install: Stress (=(M/S)*12"/ft):1141 psi O.K. Adjusted allowable stress F'b 2381 psi = Fb * adjustment factors given above Loads after install Point loads applied from solar panels - where the point load is outside the span, load = 0 Beam Load Diagram Job # P-243559-22 Cerna Residence August 15, 2022 w2 w2P2P1P3 w1 X1 X2 X3 X4 L/2 L/2 Structural Calculations Rev 7.00 1/6/17 8 Job # P-243559-22 Cerna Residence August 15, 2022 Points listed as "staggered" are on a different rafter, and therefore have no load applied Point load load location on rafter span (ft)trib (sf)D + Lr 0.6 D + 0.6 W up D + 0.6 W dnD + S Moment (ft lbs) 1 2.5 11.0 29.9 -287.7 135.5 579.9 1449.9 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.2 0.0 0.0 0.0 0.0 0.0 0.0 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 9 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 11 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 13 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 15 0.0 0.0 0.0 0.0 0.0 0.0 Staggered 0.0 0.0 0.0 0.0 0.0 0.0 Distributed loads on rafter span where not covered by solar panels w1 0.0 0.0 0.0 0.0 0.0 0.0 w2 5.0 0.0 0.0 0.0 0.0 0.0 Roof dead load 2.5 0.0 0.0 0.0 0.0 0.0 Governing load case D + S Total load (lbs)580 30 -288 136 580 1450 Cd 1.15 1.25 1.60 1.60 1.15 Load/Cd 504 24 180 85 504 Reaction on right 290 lbs = moment / rafter span Reaction on left 290 lbs = total load - reaction on left Max moment 725 ft lbs Reduced moment 604 ft lbs Applies reduction in moment due to continuity. Stress (=M/S/12"/ft):2369 psi O.K. Adjusted allowable stress F'b 2381 psi =Fb * adjustment factors above. = reaction on left * span/2 - sum (moments from point loads left of center) Structural Calculations Rev 7.00 1/6/17 9 Roof Snow Load Calculations Ground Snow Load Pg 50.0 psf Thermal factor Ct 1.1 Flat Roof Snow Load Pf = 0.7 Pg Ce Ct Is 38.5 psf Ps = Cs Pf Solar panels are assumed cold and slippery: Cs (slippery) =0.82 ASCE 7-16 fig. 7.4-1 Ps (solar panels, slippery) =31.4 psf Ps = Cs Pf Non-metal roof without solar panels is assumed NOT slippery: Cs (not slippery) =1.00 ASCE 7-16 fig. 7.4-1 Ps (roof, not slippery) =38.5 psf Ps = Cs Pf Unbalanced snow load Pitch:5:12 Is pitch < 1/2:12 or > 7:12?No W (horizontal projection of eave to ridge)15.9 ft Is rafter simply supported?No Snow density γ 20.5 pcf ASCE 7-10, Eqn. 7.7-1 Unbal. drift ht hd 1.7 ft ASCE 7-10 fig. 7-9 Unbalanced drift surcharge 0.0 psf ASCE 7-10 7.6.1 Length of drift surcharge 7.5 ft ASCE 7-10 7.6.1 Solar array distance from ridge 3.0 ft Unbalanced snow load on rafters 50.0 psf I*Pg*Cs applied as unbalanced snow on leeward slope Unbalanced snow load on solar panels 50.0 psf I*Pg*Cs applied as unbalanced snow on leeward slope Drifting/sliding snow on low roof Balanced snow height hb 1.9 ft = balanced snow load / density Clear ht from bal. snow to high roof hc 0.0 ft Upper roof length lu Lower roof width wlower Lower roof drift height hd 0.0 ft Lower roof drift max surcharge pd 0.0 psf Lower roof drift length 0.0 ft Solar array distance from upper roof 0.0 ft Lower roof drift surcharge Plow drift 0.0 psf not combined with sliding or rain surcharges Sliding snow surcharge Psliding 0.0 psf combined with balanced snow only (ASCE 7-10 7.9) Rain on snow surcharge Prain 0.0 psf combined with balanced snow only (ASCE 7-10 7.10) Snow loads used for design, considering unbalanced and/or drifting/sliding snow as needed: Ps design (solar panels)50.0 psf Ps design (roof without solar panels)50.0 psf Job # P-243559-22 Cerna Residence August 15, 2022 10 Job # P-243559-22 Cerna Residence 8/15/2022 R-1 R-2