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Home My WebLink AboutENG REPORT %VECTOR / r Lt5 E fl O 1 n E E R VSE Project Number: U2620-0100-181 April 4,2018 Green Solar Technologies ATTENTION:lake Stevenson 6400 Laure Canyon Blvd,#400 North Hollywood,CA 91606 REFERENCE: Bennie Williams Residence:322 Commanche Drive,Erwin,NC 28339 Solar Array Installation To Whom It May Concern: We have reviewed the documents and photographs provided by Green Solar Technologies relating to the installation of the solar array at the above-referenced site. Based upon our review, it is our conclusion that the installation of the solar array on this existing roof will not adversely affect this structure. It is our understanding that the structural components of the existing roof framing are in good condition and free of damage. The design of the solar panel racking (mounts, rails, etc.) is by the manufacturer or contractor. Please note a representative of Vector Structural Engineering has not physically observed the roof framing.The North Carolina Board of Examiners for Engineers and Surveyors recommends that the professional engineer or an employee of the professional engineer perform a visual inspection of the roof framing. Alternatively,the building official of the authority having jurisdiction may perform or arrange for the required inspection in lieu of inspection by the professional engineer. Desinn Parameters Code:North Carolina Building Code,2012 Edition(2009 IBC) Occupancy Category:II Design wind speed:97 mph (3-sec gust)per ASCE 7-05 Wind exposure category:C Ground snow load: 10 psf (verify with local Building department) Existing Roof Structure Roof structure:2x4 manufactured trusses @ 24"O.C. Roofing material:composite shingles Roof slope: 14° Connection to Roof Mounting connection:(I) S-5! VersaBracket 47 at max.48 in.O.C. (2)rails per row of panels,panel height not to exceed 5'-6" 651 W.Galena Park Blvd.,Ste. 101/Draper,UT 84020/T(801)990-1775/F(801)990-1776/www.vectorse.com VSE Project Number:U2620-0100-181 VECTOR Bennie Williams Residence 4/4/2018 E rl Q 1 rl E E R B Conclusions Our conclusion regarding the adequacy of the existing roof is based on the fact that the additional weight of the solar array is 3 psf or less. In the area of the solar array,other live loads will not be present or will be greatly reduced.The gravity loads in the area of the solar array are decreased; thus,the stresses of the structural elements are decreased. Therefore, the requirements of Section 807.4 of the 2015 NCEBC(2012 IEBC)are met and the structure is permitted to remain unaltered. 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. Because the increase in lateral forces is less than 10%, this addition meets the requirements of the exception in Section 807.5 of the 2015 NCEBC(2012 IEBC).Thus the existing structure is permitted to remain unaltered. 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.Particular attention must be paid to the maximum allowable spacing of connections and the location of solar panels relative to roof edges. 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. 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 '''''s''''''''''''''CAq NC Firm License:COA#P-0742 .`O • y, 044974 '• 0; 04/04/2018 Trevor Hawkes,P.E. NC License:044374-Expires: 12/31/2018 Project Engineer Enclosures TPH/wic 651 W.Galena Park Blvd.,Ste. 101/Draper, UT 84020/T(801)990-1775/F(801)990-1776/www.vectorse.com : \/ EC-1-CRWINDPRESSURE JOB NO.: U1 SUBJECT: WIND En O I n E E R 8 PROJECT: Bennie Williams Residence Components and Cladding Wind Calculations Label: , ' �, I. J�,:. , _.srt rte. Note: Calculations per ASCE 7-05 SITE-SPECIFIC WIND PARAMETERS: Basic Wind Speed [mph]: 97 Notes: Exposure Category: C Occupancy Category: II Importance Factor, I: 1.0 ADDITIONAL INPUT&CALCULATIONS: Height of Roof, h [ft]: ' .'t„ (Approximate) Comp/Cladding Location Hip? MVPS Enclosure Classification: .f Zone 1 GCp %i4 Figure 6-11C (enter largest abs. value) Zone 2 GCp �;- �p (enter largest abs. value) Zone 3 GCp L, •t : 12 (enter largest abs. value) a: 9.5 Table 6-2 zp [ft]: 900 Table 6-2 Kh: 0.95 Table 6-3 Kr: 1 Equation 6-3 Ka: 0.85 Table 6-4 Velocity Pressure, qh,[psf]: 19.4 Equation 6-15 GCp;: 0 Figure 6-5 (largest abs. value) OUTPUT: p=gl,[(GCp)—(GCp1) Equation 6-4 Zone 1 Pressure, p [psf]: 17.4 psf(1.0 W, Interior Zones') Zone 2 Pressure, p [psf]: 32.9 psf(1.0 W, End Zones') Zone 3 Pressure, p [psf]: 50.3 psf(1.0 W, Corner Zones'within a) (a= 3 ft) /� ECTOR JOB NOT.: CONN CTIO 6, SUBJECT: CONNECTION E n e 1 n E E R 9 PROJECT: Bennie Williams Residence S-51 VersaBracket 47 Connection Capacity: Demand: Pressure Max Max. Trib. Max. Uplift (1.0 Wind) Spacing Area Fastener: ,�,.i :11,,1 t...a2„.3 (psf) (ft) (ftp) Force (lbs) Zone 1 17.4 r "S`�=C.: 12 209 2 32.9 F " ' 12 395 350.3 �, ,,,, .;�; 12 604 Total Capacity: 628 lbs Demand< Capacity: CONNECTION OKAY "Capacity per ICC Report or Manufacturer Recommendations Vxmenvket 47•lava Npam4 Nana'to Seam Units safety Fedor. ImpecII • .manse .a M. Furca. Mnem �a Fa acro mnavert H 31333o-. 1433 sow H. 333_ 187 A 3 Ds to ��/ E C T O R JOB NO.: U2620-0100-161 SUBJECT: GRAVITY LOADS E ri S I rl E E R S PROJECT: Bennie Williams Residence CALCULATE ESTIMATED GRAVITY LOADS Increase due to Original ROOF DEAD LOAD (D) pitch loading Roof Pitch/12 r''6�"116.1412f1-.7-.1 Composite Shingles 2.1 1.03 2.0 psf 1/2" Plywood 1.0 1.03 1.0 psf Framing 3.0 psf Insulation 0.5 psf 1/2" Gypsum Clg. 2.0 psf M, E & Misc 1.5 psf DL 10 psf PV Array DL 3 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] " w/Solar Panel SNOW LOAD(S): Existing Array Roof Slope [x:12]: Roof Slope []: 14 14 a,4V. j ' c7= Snow Ground Load, pg [psf]: }E F".",° � I"a.^--- i � s.ASCE 7-05,Section 7.2 Terrain Category: ,. .i x1 ..=r , '^'- ASCE 7-05,Table 7-2 Exposure of Roof: 11 6"�uA ., „., ? ,:2,1 7 s ., ` ASCE 7-05,Table 7-2 Exposure Factor, Ce: 0.9 0.9 ASCE 7-05,Table 7-2 Thermal Factor, Ct: � .4• ' y ASCE 7-05,Table 7-3 Risk Category: i �y i„!(„ems ASCE 7-05,Table 1-1 Importance Factor, Is: 1.0 1.0 ASCE 7-05, Table 7-4 Flat Roof Snow Load, pr[psf]: 7 7 ASCE 7-05, Equation 7-1 Minimum Roof Snow Load, pg, [psf]: 10 10 ASCE 7-05, Section 7.3.4 Unobstructed Slippery Surface? Entitajni ASCE 7-05. Section 7.4 Slope Factor Figure: Fi•ure 7-2b Fi•ure 7-2b ASCE 7-05, Section 7.4 Roof Slope Factor, Cs: 1.00 0.93 ASCE 7-05, Figure 7-2 Sloped Roof Snow Load, ps [psf]: 7 6 ASCE 7-05, Equation 7-2 Design Snow Load, S [psf]: 10 10 -181 �/ ECTORJOB NO.: LOADCO0 SUBJECT: LOAD COMPARISON E n O I n E E R 9 PROJECT: Bennie Williams Residence Summary of Loads Existing With PV Array D [psf] 10 13 Lr[psf] 20 0 S [psf] 10 10 Maximum Gravity Loads: Existing With PV Array D+L,[psf] 30 13 ASCE 7-05,Section 2.4.1 D+S [psf] 20 23 ASCE 7-05,Section 2.4.1 Maximum Gravity Load [psi]: 30 23 Ratio Proposed Loading to Current Loading: 77% OK The gravity loads in the area of the solar array are decreased;thus,the stresses of the structural elements are decreased.Therefore,the requirements of Section 807.4 of the 2015 NCEBC(2012 IEBC)are met and the structure is permitted to remain unaltered. %VECTOR JOB NO.: S1U1 SUBJECT: SOLAROLARLAYOUT E fl O I fl E E R S PROJECT: Bennie Williams Residence III 11111I1111"� 1I „_ M,. ., _!�_� �oihoUU-- 6l9� li _ il� w S44 ro