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21 Corticelli Engineer 2018-11-19VSE Project Number: U1982-0892-181 November 13, 2018 Trinity Solar ATTENTION: Phil Smith 4 Open Square Way, Suite 410 Holyoke, MA 01040 REFERENCE: Lindsay Slabich Residence: 21 Corticelli Street, Northampton, MA 01062 Solar Array Installation To Whom It May Concern: Per your request,we have reviewed the existing structure at the above referenced site.The purpose of our review was to determine the adequacy of the existing structure to support the proposed installation of solar panels on the roof as shown on the panel layout plan.Based upon our review,we conclude that the existing structure will require retrofit in order to support the proposed solar panel installation.The existing rafters of roof 1 must be retrofit by installing a new 2x6 the full length of the existing rafter. Install the new 2x6 rafter with 16d sinkers at 6" O.C. staggered. Roof 3 is permitted to remain unaltered. Design Parameters Code: Massachusetts State Residential Code (780 CMR Chapter 51, 9th Edition (2015 IRC)) Risk Category: II Design wind speed: 117 mph (3-sec gust) per ASCE 7-10 Wind exposure category: C Ground snow load: 40 psf Existing Roof Structure Roof structure: true 2x4 rafters @ 24" O.C. Roofing material: asphalt shingles Roof slope: 40° Connection to Roof Mounting connection: (1) 5/16" lag screw w/ min. 2.5" embedment into framing at max. 72" O.C. along rails Conclusions Based upon our review,we conclude that the existing structure will require retrofit in order to support the proposed solar panel installation.The glass surface of the solar panels allows for a lower slope factor per ASCE 7,resulting in reduced design snow load on the panels.The attached calculations verify the adequacy of the roof to support the solar array after the aforementioned retrofit is complete. 651 W. Galena Park Blvd., Ste. 101 / Draper, UT 84020 / T (801) 990-1775 / F (801) 990-1776 / www.vectorse.com VSE Project Number: U1982-0892-181 Lindsay Slabich Residence 11/13/2018 The solar array will be flush-mounted (no more than 6"above the roof surface)and parallel to the roof surface.Thus,we conclude that any additional wind loading on the structure related to the addition of the proposed solar array is negligible. The attached calculations verify the capacity of the connections of the solar array to the existing roof against wind (uplift), the governing load case. Limitations Installation of the solar panels must be performed in accordance with manufacturer recommendations.All work performed must be in accordance with accepted industry-wide methods and applicable safety standards.The contractor shall notify Vector Structural Engineering,LLC should any damage,deterioration or discrepancies between the as-built condition of the structure and the condition described in this letter be found.Connections to existing roof framing must be staggered,except at array ends,so as not to overload any existing structural member.The use of solar panel support span tables provided by others is allowed only where the building type,site conditions,site-specific design parameters,and solar panel configuration match the description of the span tables.The design of the solar panel racking (mounts,rails,etc.),and electrical engineering is the responsibility of others.Waterproofing around the roof penetrations is the responsibility of others.Vector Structural Engineering assumes no responsibility for improper installation of the solar array. VECTOR STRUCTURAL ENGINEERING, LLC 11/13/2018 _______________________________________________________ Wells Holmes, S.E. MA License: 54240 - Expires: 06/30/2020 Project Engineer Enclosures WLH/koc 11/13/2018 651 W. Galena Park Blvd., Ste. 101 / Draper, UT 84020 / T (801) 990-1775 / F (801) 990-1776 / www.vectorse.com JOB NO.:U1982-0892-181 SUBJECT:WIND PRESSURE PROJECT:Lindsay Slabich Residence Label:Note: Calculations per ASCE 7-10 SITE-SPECIFIC WIND PARAMETERS: Basic Wind Speed [mph]:117 Notes: Exposure Category:C Risk Category:II Importance Factor, I: ADDITIONAL INPUT & CALCULATIONS: Height of Roof, h [ft]:20 (Approximate) Comp/Cladding Location:Hip?No Enclosure Classification: Zone 1 GCp:1.0 Figure 30.4-2C (enter largest abs. value) Zone 2 GCp:1.2 (enter largest abs. value) Zone 3 GCp:1.2 (enter largest abs. value) α:9.5 Table 26.9-1 zg [ft]:900 Table 26.9-1 Kh:0.90 Table 30.3-1 Kzt:1 Equation 26.8-1 Kd:0.85 Table 26.6-1 Velocity Pressure, qh [psf]:26.9 Equation 30.3-1 GCpi:0 Table 26.11-1 (largest abs. value) OUTPUT:Equation 30.9-1 Zone 1 Pressure, p [psf]:26.9 psf (1.0 W, Interior Zones*) Zone 2 Pressure, p [psf]:32.2 psf (1.0 W, End Zones*) Zone 3 Pressure, p [psf]:32.2 psf (1.0 W, Corner Zones* within a) (a= 3 ft) Solar Panel Array Gable Roofs 27° < θ ≤ 45° Enclosed Buildings Components and Cladding Wind Calculations ()()piphGCGCqp−= VECTOR STRUCTURAL ENGINEERS JOB NO.:U1982-0892-181 SUBJECT:CONNECTION PROJECT:Lindsay Slabich Residence Lag Screw Connection Capacity:Demand: Lag Screw Size [in]:5/16 Cd:1.6 NDS Table 2.3.2 Embedment1 [in]:2.5 Grade: Capacity [lbs/in]:205 NDS Table 12.2A 1 16.1 6.0 16.5 266 Number of Screws:1 2 19.3 6.0 16.5 319 Prying Coefficient:1.4 3 19.3 6.0 16.5 319 Total Capacity [lbs]:586 Demand< Capacity:CONNECTION OKAY SPF (G = 0.42) Pressure (0.6 Wind) (psf) Max Tributary Width (ft) Max. Trib. Area2 (ft2) Max. Uplift Force (lbs) Zone 1. Embedment is measured from the top of the framing member to the beginning of the tapered tip of the lag screw. Embedment in sheathing or other material is not effective. The length of the tapered tip is not part of the embedment length. 2. 'Max. Trib Area' is the product of the 'Max. Tributary Width' (along the rails) and 1/2 the panel width/height (perpendicular to the rails). VECTOR STRUCTURAL ENGINEERS JOB NO.:U1982-0892-181 SUBJECT:GRAVITY LOADS PROJECT:Lindsay Slabich Residence CALCULATE ESTIMATED GRAVITY LOADS ROOF DEAD LOAD (D) Increase due to pitch Original loading Roof Pitch/12 10.1 Asphalt Shingles 2.6 1.31 2.0 psf 1/2" Plywood 1.3 1.31 1.0 psf Framing 3.0 psf Insulation 0.0 psf 1/2" Gypsum Clg.0.0 psf M, E & Misc 0.0 psf DL 7 psf PV Array DL 4 psf ROOF LIVE LOAD (Lr) Existing Design Roof Live Load [psf]20 ASCE 7-10, Table 4-1 Roof Live Load With PV Array [psf]20 SNOW LOAD (S):Existing w/ Solar Panel Array Roof Slope [x:12]:10.1 Roof Slope [°]:40 Snow Ground Load, pg [psf]:40 ASCE 7-10, Section 7.2 Terrain Category:C ASCE 7-10, Table 7-2 Exposure of Roof:Fully Exposed ASCE 7-10, Table 7-2 Exposure Factor, Ce:0.9 ASCE 7-10, Table 7-2 Thermal Factor, Ct:1.1 ASCE 7-10, Table 7-3 Risk Category:II ASCE 7-10, Table 1.5-1 Importance Factor, Is:1.0 ASCE 7-10, Table 1.5-2 Flat Roof Snow Load, pf [psf]:35 ASCE 7-10, Equation 7.3-1 Minimum Roof Snow Load, pm [psf]:0 ASCE 7-10, Section 7.3.4 Unobstructed Slippery Surface?Yes ASCE 7-10, Section 7.4 Slope Factor Figure:Figure 7-2b ASCE 7-10, Section 7.4 Roof Slope Factor, Cs:0.50 ASCE 7-10, Figure 7-2 Sloped Roof Snow Load, ps [psf]:18 ASCE 7-10, Equation 7.4-1 Design Snow Load, S [psf]:1832 10.1 40 40 C Fully Exposed 0.9 1.1 II 1.0 35 0 No Figure 7-2b 0.92 32 Abbrev GRADES Fbxx (psi) Fvxx (psi) g (lb/ft3) JOB NO.:U1982-0892-181 DFL#1 DFL#1 1,000 180 32 DFL#2 DFL#2 900 180 32 DF1 (5X)DFL#1 5X5 & LARGER 1,350 170 32 SPF#2 SPF#2 875 135 26.2 SP#2 SP#2 1,100 175 34.3 PROJECT:Lindsay Slabich Residence SUBJECT:BEAMS 24F-V4 24F-V4 2,400 240 32 24F-V8 24F-V8 2,400 240 40 LVL (1.9)LVL (1.9X106E)2,600 285 40 DESIGN LOADS:Load Types:Snow Live Dead LVL (2.0)LVL (2.0X106E)2,200 285 42 Roof 32 20 8 CRITERIA (L/)DTL DLL DDL LSL LSL (1.3X106E)1,700 400 42 Solar 3.5 A(BLANK)120 240 STL36 GRADE 36 STEEL 21,600 14,400 490 B 240 480 STL46 GRADE 46 STEEL 27,700 16,500 490 C 600 800 STL50 GRADE 50 STEEL 30,000 20,000 490 Label Length 'L' (ft) *Roof Trib (ft) Floor Trib (ft) Wall Trib (ft) Add'l Live Load (plf) Add'l Solar Load (plf) Point Load From React (A,B)Dist 'a' (ft) Point Live Load 'PLL' (lb) Point Dead Load 'PDL' (lb)# PLIESGrade Size "BM/HDR"D CRITERIACr CD CF,V Ra (lb)Rb (lb) Mmax (ft-lb) Mallow (ft-lb) Vmax (lb) Vallow (lb) DTL (in) DTLallow (in) DLL (in) (SEE COND 'C') DLLallow (in) (SEE COND 'C') 1.5DL GLB Camb Check Roof 3 5 2 7.0 (1)SPF#2 2x4 1.15 1.15 1.50 221 221 276 443 195 543 0.165 0.500 0.075 0.250 0.62 M Roof 1 10 0.68 2.4 (1)SPF#2 2x4 (True)1.15 1.15 1.00 150 150 374 514 140 828 0.451 1.000 0.204 0.500 0.73 M Roof 1 10 1.32 4.6 (1)SPF#2 2X6 1.15 1.15 1.30 292 292 729 948 265 854 0.451 1.000 0.204 0.500 0.77 M *Roof trib. adjusted based on the ratio of moment of Inertia. Exx (psi) 1,800,000 29,000,000 29,000,000 1,700,000 1,800,000 1,900,000 29,000,000 2,000,000 1,300,000 1,400,000 1,600,000 1,600,000 1,400,000 VECTOR STRUCTURAL ENGINEERS JOB NO.:U1982-0892-181 SUBJECT:SOLAR LAYOUT PROJECT:Lindsay Slabich Residence