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Home My WebLink AboutMaryam Hadavi letter - MN (Revised) (S&S) TERRA ENGINEERING CONSULTING Structural Letter of Approval Date: 11 October 2022 Solcius LLC 9124 Grand Ave S Suite 105 Minneapolis, MN 55420 Maryam Hadavi Residence: 5466 W Bavarian Pass, Fridley, MN 55432 Dear Sir/Madam, Terra Engineering Consulting (TEC)has performed a structural load comparison for the existing roof based on the existing and proposed load conditions, and determined that the structure can support the additional weight of the proposed solar panel system. The attached calculations are based off the assumptions that the existing structural components are in good condition and that they meet industry standards. The design information and assumptions that the calculations are based off are located in the attached References page. The contractor shall notify TEC of any damage to the roof system encountered at the time of installation. The design of the solar panel's mounting hardware is to be provided by the manufacturer or installer. Structural observation or construction inspections will not be performed by TEC, Engineer-of-Record(EOR), nor their representatives. Conclusion This engineering analysis was performed in accordance with ASCE 7-16 design method. In general, this design method is a comparison of the roof loads before and after the solar panel installation. Snow load in the area of the panels will be reduced due to the roof pitch and the panel's slippery surface, as justified in section 7.4 in ASCE 7-16; and in this scenario, the total stresses of the structural elements are decreased after the solar system is installed. The total load of the solar panels is assumed to not exceed 3 psf, and the typical 20 psf live load will not be present in the area of the panels, as defined per Section 1607.13.5.1 in 2020 MBC. The total combined gravity loads result in an increase of less than 5% to the existing load, meeting Section 806.2 of 2020 MBC, thus the structure still meets standards. Regarding lateral loads, the wind load controls, and due to the low profile of the panels (3" to 6") as well as PV frame, wiring, conduit, and structural component below the module causing restriction in airflow which allow it to be considered as "partially enclosed structure"; thus the additional pressure on the structure is considered negligible. The addition of total PV system weight result in an increase under 10% of the total roof weight, and meets the seismic requirements in Section 502.5 of 2020 MBC. TEC concludes that the installation of solar panels on existing roof will not affect the structure, and allows it to remain unaltered under the applicable design standards. These conclusions are based on the attached calculations. 1863 GOLDENROD WAY/NORTH SARATOGA SPRINGS,UT 84045/T(801)-616-6204 General Instructions The solar array mounting system shall be connected to every other joist (48 inch maximum penetration spacing) in order to distribute the load evenly. The installer shall stagger the connections into the roof framing to not overload any existing structural members.Installation and waterproofing shall be performed within accepted industry standards. Best Regards, Terra Engineering Consulting, PLLC �0\4•.E:..FgR ��.�'• •'�9�; I hereby certify that this plan, specification, or report was LICENSED • I* ; prepared by me or under my direct supervision and that I PROFESSIONAL 13=Oct 2022 ENGINEER am a duly Licensed Professional Enqineer under the laws of Exi' N 49529_ ?•Q 30 June 2024 the state of Minnesota. e; ' '"� h '0 Signature: t 2022 •,FpF M NN�� Typed or Printed Name: ANTHONY E. FARMAND Date: 13 Oct 2022 License Number: 49529 Anthony E. Farmand, PE Civil Engineer 1863 GOLDENROD WAY/NORTH SARATOGA SPRINGS,UT 84045/T(801)-616-6204 References Design Parameter Code: 2020 Minnesota Building Code/Residential Code, ASCE 7-16, and National Design Specification for Wood Construction (NDS) 2015 Edition Load Combination: ASD Risk Category: II Ground Snow load: 50 psf Roof Snow load: 34.7 psf Design Wind Speed: 115 mph (3 sec gust)per ASCE 7-16 Seismic Design Category: D Wind Exposure Category: C Existing Roof Structure Roof framing: 2x4 Pre-fab trusses at 24" O.C. Roof material: Composite shingles Roof slope: 21' Roof type: Gable Solar Panels Weight: 3 psf Connections: (1) 5/16"Lag screw with 2.5" min. embedment into the framing at 48" O.C. spaced along the rail 1863 GOLDENROD WAY/NORTH SARATOGA SPRINGS,UT 84045/T(801)-616-6204 E. LICENSED = Date: 10/11/2022 PROFESSIONAL .o13-Oct 2022 Client: Maryam Hadavi s t ♦ ENGINEER Terra ;N 49529 'Q 30 June 2024 Subject: Gravity load Englnee ing C.-11'nq Gravity load calculations �' F ""'N� Snow load (S) Existing w/solar panels Roof slope(°): 21 21 Ground snow load, pg(psf): 50 50 ASCE 7-16, C7.2 Terrain category: C C ASCE 7-16,table 7.3-1 Exposure of roof: Fully exposed Fully exposed ASCE 7-16,table 7.3-1 Exposure factor, Ce: 0.9 0.9 ASCE 7-16,table 7.3-1 Thermal factor, Ct: 1.1 1.1 ASCE 7-16,table 7.3-2 Risk Category: II II ASCE 7-16,table 1.5-1 Whcrc px is 20 lb/ft2(0.96 kN/m'-)or less: P.=I,pR (Importance Factor times p1,) Where pR exceeds 20 ab/ft2(0.96 kN/m2): pf=0.7CeC,I,p, (7.3-1) pm=20(1,) (20 lb/W times Importance Factor) Importance Factor, Is: 1 1 ASCE 7-16,table 1.5-2 Flat roof snow load, pf(psf): 34.7 34.7 ASCE 7-16, equation 7.3-1 Minimum roof snow load, pm (psf): 0 0 ASCE 7-16, equation 7.3-4 Unobstructed Roof Surface type: Other slippery surface ASCE 7-16, C7.4 Roof slope factor, Cs: 1 0.82 ASCE 7-16, C7.4 P,= C,pf (7.4-1) ASCE 7-16, equation 7.4-1, Design Sloped roof snow load, ps[psf]: 34.7 28.4 Snow Load (S) Roof dead load (D) Roof pitch/12 4.6 Composite shingles 3 psf 1/2" Gypsum clg. 2.2 psf 1/2" plywood 1 psf insulation 0.8 psf Framing 3 psf M, E& Misc 1.5 psf Roof DL without PV arrays 12.3 psf PV Array DL 3 psf Roof live load(Lr) Existing w/solar panels Roof Live Load 20 0 2018 IBC,Section 1607.13.5.1 ASD Load combination: Existing With PV array D [psf] 12.3 15.3 ASCE 7-16,Section 2.4.1 D+L[psf] 12.3 15.3 ASCE 7-16,Section 2.4.1 D+[Lr or S or R] [psf] 47.0 43.7 ASCE 7-16,Section 2.4.1 D+0.75L+0.75[Lr or S or R] [psf] 38.3 36.6 ASCE 7-16,Section 2.4.1 Maximum gravity load [psf]: 47.0 43.7 Ratio proposed load to existing load: 93.11% The stresses due to gravity load in the area of the solar panels is reduced,allowing the structure to remain unaltered. `1111111/,� _ LICENSED •' 2' PROFESSIONAL ';�= Date: 10/11/2022 t _ ENGINEER : 13_Oct 2022 Client: Maryann Hadavi Terra N 49529_ (Q 30 June 2024 Subject: Wind load and 0: Connection Wind Pressure Calculation '�,,OF Mi 14 p = q,,((GCn) - (GC,,;)) (30.9-1) Basic wind speed (mph) 115 Risk category II Exposure category C Roof type Gable Figure for GCp values ASCE 7-16 Figure 30.3-2A-1 Zone 1 Zone 2 Zone 3 GCp (neg) -0.9 -1.7 -2.6 GCp (pos) 0.5 0.5 0.5 zg(ft) 900 (ASCE 7-16 Table 26.11-1) a 9.5 (ASCE 7-16 Table 26.11-1) Kzt 1 (ASCE 7-16 Equation 26.8-1) (only changes if structure located on a hill or ridge) Kh 0.9 (ASCE 7-6 Table 26.10-1) Kd 0.85 (ASCE 7-16 Table 26.6-1) Velocity Pressure,qh (psf) 25.90 (ASCE 7-16 Equation 26.10-1) Gcpi 0 (ASCE 7-16 Table 26.13-1) (0 for enclosed buildings) Zone 1 Zone 2 Zone 3 W Pressure, (neg) [psf] -23.31 -44.03 -67.34 W Pressure, (pos) [psf] 12.95 12.95 12.95 W Pressure, (Abs. max) [psf] 23.31 44.03 67.34 Connection Calculations Capacity Connection type: Lag screw Lag screw diameter: 5/16 Embedment(in): 2.5 Framing grade: DFL#2 G: 0.5 Capacity[Ibs/in]: 266 (2015 NDS table 12.2A) Number of screws: 1 Total capacity [Ibs]: 665.00 Demand Anchor spacing: 48 in Anchor spacing in roof corners: 48 in (0.6 W Pressure, Max. psf),see tributary Zone Note 1 area (ft^2) Max Uplift force (Ibs) 1 14.0 11 153.8 2 26.4 11 290.6 3 40.4 11 444.4 Connection Meets Demand Note 1:0.6W results from dominant ASD combo [0.6D+0.6W] (ASCE 7-16 2.4.1).