The URL can be used to link to this page

Home My WebLink AboutRobFisherLetterSS619bd71095c19Engineering Alliance, Inc https://www.eng-alliance.com 22 November 2021 UNIRAC 1411 Broadway Blvd. NE Albuquerque, NM 87102 REFERENCE: ROB FISHER: 4811 PENDULA DR, CARMEL, IN 46033 Solar Array Installation Based upon our review, we conclude that the existing structure is adequate to support the proposed solar panel installation. Design Parameter Code: International Building Code 2012 (IBC 2012) Risk Category: II Design wind speed: 115 MPH Wind exposure category: C Ground snow load: 20 PSF Seismic design category: B Existing Roof Structure Existing Roof Structure: 2"X4" RAFTERS @24" O.C. Roofing material: COMP SHINGLE Connection to Roof Mounting connection: (1) 5/16 in lag screw w/ min. 2.5 in embedment into framing at max. 72 in o.c. along rails (2) rails per row of panels, evenly spaced; panel length perpendicular to the rails not to exceed 68.5 in Conclusions 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. To Whom It May Concern: Based upon ourreview, we conclude that the existing structure is adequate to support the proposed solar panel installation. In the area of the solararray, other live loads will not be present orwill be greatly reduced .The glass surface ofthe solar panels allows for a lower slope factor perASCE7, resulting in reduced design snowload on the panels.The gravity loads and; thus, the stresses of the structural elements, in the area of the solar array are either decreased or increased by no more than 5%. Therefore, the requirements of Section 403.3 of the 2012 IEBC are met and the structure is permitted to remain unaltered. 4603 April Meadow Way, Sugar Land, TX 77479. Ph: 832 865 4757475712/20/21 Engineering Alliance, Inc https://www.eng-alliance.com Limitations Engineering Alliance, Inc Saddam Ahmad P.E., P.Eng. President and Lead Structural Engineer Engineering Alliance, Inc Phone: 832 865 4757 The solar array will be flush-mounted (not more than 5 in 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. Regarding seismic loads, we conclude that any additional forces will be small. As perSection 1613.1, Exception-1of the 2012 IBC, detached one-and two-family dwellings with Seismic Design Category A, B or C or located where the mapped short-period spectral response acceleration, Ss, is less than 0.4 g are exempted from seismic load. Thus the existing lateral force resisting system is permitted to remain unaltered. 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 must notify Engineering Alliance, Inc should anydamage, deterioration or discrepancies between the as-built condition ofthe 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 are 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. Engineering Alliance, Inc assumes no responsibility for improper installation of the solar array. 4603 April Meadow Way, Sugar Land, TX 77479. Ph: 832 865 47574757 22-NOV-2021 12/20/21 Project: Location: Designer:MIM Date: Calculations per ASCE 7-10 International Building Code 2012 (IBC 2012) ROOF DEAD LOAD (D): Material Design material weight (psf) Increase due to pitch Material weight (psf) COMP SHINGLE 2.50 1.25 2 1/2" Plywood 1.3 1.25 1 Framing 3 3 Insulation 0.5 0.5 1/2" Gypsum Clg. 2.5 1.25 2 M, E & Misc 1.5 1.5 Total Dead Load 11.3 PV Array Dead Load 3.8 1.25 3 ROOF LIVE LOAD (Lr): Existing Design Roof Live Load [psf] 20 ASCE 7-10, Table 4-1 Roof Live Load With PV Array [psf] 0 SEISMIC LOAD, (E): Risk category: II Table 1.5-1 Seismic Design Category: B Table 11.6-2 Ip: 1 Table 1.5-2 Site Class: D Rp: 1.5 Table 13.6-1 Ss: 0.146 S1: 0.081 ap: 1 Table 13.6-1 z: 1 ft h: 1 ft z/h: 1 Fa: 1.6 Table 11.4-1 Fv: 2.4 Table 11.4-2 SMS: 0.234 Eqs. 11.4-1 SM1: 0.194 Eqs. 11.4-2 SDS: 0.156 Eqs. 11.4-3 SD1: 0.130 Eqs. 11.4-4 ROB FISHER 22 November 2021 4811 PENDULA DR, CARMEL, IN 46033 Engineering Alliance, Inc 12/20/21 Project: Location: Designer:MIM Date: ROB FISHER 22 November 2021 4811 PENDULA DR, CARMEL, IN 46033 Engineering Alliance, Inc SITE-SPECIFIC WIND PARAMETERS: Basic Wind Speed [mph]: 115 Exposure Category: C Sec. 26.7.3 Risk Category: II Table 1.5-1 Height of Roof, h [ft]: 30 (Approximate) Roof Slope [°]: 37 Site Elevation [ft]: 760 Comp/Cladding Location: FIGURE 30.4-2C Enclosure Classification: Enclosed Buildings Zone 1 GCp: 1.0 (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: 0.98 Table 30.3-1 Kzt: 1 Equation 26.8-1 Kd: 0.85 Table 26.6-1 Velocity Pressure, qh [psf]: 28.27 Equation 30.3-1 GCpi 0 Table 26.11-1 PRESSURES: p = qh((GCp)-(GCpi)) (lb/ft2) Equation 30.9-1 Zone 1 : 28.3 psf (1.0 W) Zone 2 : 33.9 psf (1.0 W) Zone 3 : 33.9 psf (1.0 W) (a= 3 ft) Gable Roofs, 27° < θ ≤ 45° 12/20/21 Project: Location: Designer:MIM Date: ROB FISHER 22 November 2021 4811 PENDULA DR, CARMEL, IN 46033 Engineering Alliance, Inc COMPARE WIND & SEISMIC LOADS FOR CONNECTION (1 Sq. Ft. Section) Wind Load, W: Wind pressure, p: 17.0 psf (Zone 1: 0.6 W from wind pressure calculation) Height, h: 1 ft Width, w: 1 ft Fperp: 17.0 lb (Uplift) Seismic Load, E: 0.7 * Fp ,min: 0.098 lb 0.7 * Fp ,max: 0.523 lb 0.7 * Fp ,vert: 0.065 lb 0.7 * Fp ,long: 0.262 lb 0.7*Fp ,perp: 0.210 lb (uplift) Wind (uplift) Controls Connection Design CHECK INCREASE IN OVERALL SEISMIC LOADS SEISMIC: Seismic Design Category: B As per Section 1613.1, Exception-1 of the 2012 IBC, Seismic load is Exempted. 12/20/21 Project: Location: Designer:MIM Date: ROB FISHER 22 November 2021 4811 PENDULA DR, CARMEL, IN 46033 Engineering Alliance, Inc Lag Screw Connection Tributary Length (in): 68.5 Max Tributary Width (in): 72 Capacity: Lag Screw Size [in]: 5/16 Cd: 1.6 NDS Table 2.3.2 Embedment 1 [in]: 2.5 Grade: SPF (G = 0.42) Capacity [lbs/in]: 205 NDS Table 12.2A Number of Screws in tension: 1 Prying Coefficient: 1.4 Total Capacity [lbs]: 586 Demand: Zone 1 : 14.0 6.0 2.9 17.1 239 Zone 2 : 17.4 6.0 2.9 17.1 297 Zone 3 : 17.4 6.0 2.9 17.1 297 Total Tension Force(lbs): 297 Demand< Capacity: 50.7%, OK Notes 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). Max. Trib. Length (ft) Pressure (0.6 Wind) (psf) Max Tributary Width (ft) Max. Trib. Area2 (ft2) Max. Uplift Force (lbs)Zone 12/20/21 Project: Location: Designer:MIM Date: ROB FISHER 22 November 2021 4811 PENDULA DR, CARMEL, IN 46033 Engineering Alliance, Inc SNOW LOAD (S): Existing w/ Solar Panel Array Roof Slope [x:12]: 9.0 9.0 Roof Slope [°]: 37 37 Snow Ground Load, pg [psf]: 20 20 ASCE 7-10, Section 7.2 Surface Roughness Category: C C ASCE 7-10, Table 7-2 Exposure of Roof: Fully Exposed Fully Exposed ASCE 7-10, Table 7-2 Exposure Factor, Ce: 0.9 0.9 ASCE 7-10, Table 7-2 Thermal Factor, Ct: 1.1 1.1 ASCE 7-10, Table 7-3 Risk Category: II II ASCE 7-10, Table 1.5-1 Importance Factor, Is: 1 1 ASCE 7-10, Table 1.5-2 Flat Roof Snow Load, pf [psf]: 14 14 ASCE 7-10, Equation 7.3-1 Minimum Roof Snow Load, p m [psf]: 0 0 ASCE 7-10, Section 7.3.4 Unobstructed Slippery Surface? NO YES ASCE 7-10, Section 7.4 Slope Factor Figure: Figure 7-2b Figure 7-2b ASCE 7-10, Section 7.4 Roof Slope Factor, Cs: 0.94 0.55 ASCE 7-10, Figure 7-2 Sloped Roof Snow Load, ps [psf]: 13 8 ASCE 7-10, Equation 7.4-1 Design Snow Load, S [psf]: 13 8 Summary of Loads Existing With PV Array D [psf] 11 15 Lr [psf] 20 0 S [psf] 13 8 Maximum Gravity Loads: Existing With PV Array (D + Lr) / Cd [psf] 25 17 ASCE 7-10, Section 2.4.1 (D + S) / Cd [psf] 21 20 ASCE 7-10, Section 2.4.1 (Cd = Load Duration Factor = 0.9 for D, 1.15 for S, and 1.25 for Lr) Maximum Gravity Load [psf]: 25 20 79% OKRatio Proposed Loading to Current Loading: The gravity loads and; thus, the stresses of the structural elements, in the area of the solar array are either decreased or increased by no more than 5%. Therefore, the requirements of Section 403.3 of the 2012 IEBC are met and the structure is permitted to remain unaltered. 12/20/21