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24A-006 (5) %vcTPR 2 I9_ Qo-( UTAH OFFICES Sandy Layton E n e I n E E R s St. George Project Number: U1982-0186-171 April 24,2017 Trinity Solar 4 Open Square Way,Suite 410 Holyoke.MA 01040 ATTENTION: Phil Smith REFERENCE: Michael Grygorcewicz Residence:35 Terrace Lane,Northampton,MA 01060 Solar Panel Installation Dear Mr.Smith: Per your request, we have reviewed the attached layout and photos relating to the installation of solar panels at the above-referenced site.The following materials and components are proposed in the installation of the solar panels. Roof Structure:2x6 Rafters at 16 in O.C. Roof Material:Composition Shingles Mounting Connections:5/16-Lag Screw with 2.5"Embedment at 6'O.C.maximum. Based upon our review, it is our conclusion that the installation of solar panels on this existing roof will not adversely affect the stmcture of this house. The design of solar panel supporting members is by the manufacturer and/or installer. The adopted building code in this jurisdiction is the 2009 International Residential Code and ASCE 7-05. Appropriate design parameters which must be used in the design of the supporting members and connections are listed below: Ground snow load:40 psf per Massachusetts amendments to the IRC(verify with local building department) Roofsnow load:28 psf per Massachusetts amendments to the IRC(verify with local building department) Design wind speed: 92 mph(3-sec gust) Wind exposure:Category C Our conclusion regarding the adequacy of the existing roof is based on the fact that the additional weight related to the solar panels is less than 3.5 pounds per square foot In the area of the solar panels,no 20 psf live loads will he present. Regarding snow loads,it is our conclusion that since the panels are slippery,effective snow loads will be reduced in the areas of the panels. The attached calculations verify the capacity of the connections against wind, the governing load case. Solar panels will be flush-mounted, parallel to and no more than 6" above the roof surface. Thus, it is our conclusion that any additional wind or seismic loadings related to the addition of these solar panels is negligible. During design and installation,particular attention must be paid to the maximum allowable spacing of attachments and the location of solar panels relative to roof edges. The use of solar panel support span tables provided by the manufacturer is allowed only where the building type, site conditions, and solar panel configuration match the description of the span tables.Attachments to existing roof joist or rafters must be staggered so as not to over load any existing structural member. Waterproofing around the roof penetration is the responsibility of others. All work performed must he in accordance with accepted industry-wide methods and applicable safety standards. Vector Structural Engineering assumes no responsibility for improper installation of the solar panels. Please note a representative of Vector Structural Engineering has not physically observed the roof framing. Our conclusions are based upon the assumption that all structural roof components and other supporting elements are in good condition,free of damage and deterioration,and are sized and spaced such that they can resist standard roof loads. Very truly yours, VECTOR STRUCTURAL ENGINEERING,LLC tk cm Roger Alworth,P.E. I Principalal 4 ' RTAirsl 04/24/2017 9138 S. State St., Suite 101 /Sandy. UT 840701 T(801)990-1775 /F(801) 990-1776/www.vectorse.com S/ ECTCR JOB NO.: U1982-0186-171 E n e I n e E R s PROJECT: MICHAEL GRYGORCEWICZ RESIDENCE SUBJECT: WIND PRESSURE Components and Cladding Wind Calculations Label: Solar Panel Array Note: Calculations per ASCE 7-05 SITE-SPECIFIC WIND PARAMETERS: Basic Wind Speed [mph]: 92 Notes: Exposure Category: C Occupancy Category: II Importance Factor, I: 1.00 ADDITIONAL INPUT& CALCULATIONS: Height of roof, h [ft]: 25 (Approximate) Comp/Cladding Location: Gable/Hip:iti±nfs 7°<9 5zr, Enclosure Classification: Enclosed Buildings Zone 1 GCp: 0.9. Figure 6-11C (enter largest abs. value) Zone 2 GCp: L7 (enter largest abs. value) Zone 3 GCp: '26 (enter largest abs. value) a: 9.5 Table 6-2 zv [ftj: 900 Table 6-2 Kh: 0.945 Table 6-3 Kr: 1 Equation 6-3 Kd: 0.85 Table 6-4 Velocity Pressure, qh [psf]: 17.4 Equation 6-15 GCp;: 0 Figure 6-5 (largest abs. value) OUTPUT: p=qh[(GCp)-(GCp;)j Zone 1 Pressure, p [psf]: 15.67 psf(1.0W, Interior Zones*) Zone 2 Pressure, p [psf]: 29.60 psf(1.0W, End Zones*) Zone 3 Pressure, p [psf]: 45.26 psf(1.0W, Corner Zones* within a) (*a=assumed=3') %VECTOR JOB NO.: U1982-0186.171 EFIGIFIEERS PROJECT: MICHAEL GRYGORCEWICZ RESIDENCE SUBJECT: CONNECTION CAPACITY Lag Screw Connection Capacity: Demand: Lag Screw Size: 5/16 Cd: 1.6 Pressure Max Max. Trib. (1.0 Wind) Spacing Area Max. Uplift Embedment: 2.5 in (psi) (ft) (ftz) Force (Ibs) Grade: SPF (G = 0.42) Capacity: 205 lbs/in. emb. Zone 1: 15.7 4 12 188 Number of Screws: 1" Zone 2: 29.6 4 12 355 Total Capacity: 820 lbs Zone 3: 45.3 4 12 543 Demand< Capacity: CONNECTION OKAY "V E C i O R JOB NO.: U1982-0186-171 E rl G I n E E R S PROJECT: MICHAEL GRYGORCEWICZ RESIDENCE SUBJECT: GRAVITY LOADS CALCULATE ESTIMATED GRAVITY LOADS Increase due to Original DEAD LOAD (D) pitch loading Roof Pitch/12 I 5.1 Composite/Asphalt Shingles 4.3 1.09 4.00 psf 1/2" Plywood 1.1 1.09 1.00 psf Framing 3.0 psf Insulation 0.8 psf 1/2" Gypsum CIg. 2.2 psf M, E & Misc 1.5 psf DL 12.9 psf PV Array DL 3.0 psf ROOF LIVE LOAD (Lr) Existing Design Roof Live Load [psf] 20 ASCE 7-05, Table 4-1 Roof Live Load With PV Array [psf] 11.1111.E 2015 BC, Section 1607.12.5 SNOW LOAD (S): Existing With PV Array Roof Slope(:12): 5.1 " 5.1 Roof Slope [1: 23 23 Snow Ground Load, pg [psf]: ;40 40 ASCE 7-05, Section 7.2 Terrain Category: 4't - C ; C -„ASCE 7-05, Table 7-2 Exposure of Roof: Fully Exposed [z Fully E4 bbed^`" ASCE 7-05, Table 7-2 Exposure Factor, Ce: 0.9 0.9 ASCE 7-05, Table 7-2 Thermal Factor, q: N1 ' ' t "" ,.,] <{ASCE 7-05, Table 7-3 Risk Category: II <._ II & ASCE 7-05,Table 1-1 Importance Factor, Is: 1.0 1.0 ASCE 7-05, Table 7-4 Flat Roof Snow Load, pt [psf]: 28 28 ASCE 7-05, Equation 7-1 Minimum Roof Snow Load, pm [psf]: 0 0 ASCE 7-05, Section 7.3.4 Unobstructed Slippery Surface? ""No - Yes. 'I ASCE 7-05, Section 7.4 Slope Factor Figure: Figure 7-2b Figure 7-2b ASCE 7-05, Section 7.4 Roof Slope Factor, C3: 1.000 0.783 ASCE 7-05, Figure 7-2 Sloped Roof Snow Load, p3 [psf]: 28 22 ASCE 7-05, Equation 7-2 Design Snow Load, S [psf]: 28 22 �\IECTOR JOB NO.: U1982-0186-171 E rl G I M E E R S PROJECT: MICHAEL GRYGORCEWICZ RESIDENCE SUBJECT: LOAD COMPARISON Summary of Loads Existing With PV Array D [psf] 13 16 Lr[psf] 20 0 S [Psf] 28 22 Maximum Gravity Loads: Existing With PV Array D+L,[psf] 33 16 ASCE 7-05, Section 2.4.1 D+S [psf] 41 38 ASCE 7-05, Section 2.4.1 Maximum Gravity Load [psf]: 41 38 Ratio Proposed Loading to Current Loading: 92.6% OK The gravity loads in the area of the solar panels are decreased;thus, the stresses of the structural elements are decreased.Therefore,the requirements of Section 3403.3 of the Massachusetts State Building Code,8th Edition(2009 IBC) are met and the structure is permitted to remain unaltered.