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IDaniel W. DUnzik Architect LEED-AP <br /> 370 Burnt Hill Rd. Skillman, NJ.08558 908-872-3664 <br /> Studiogdesign@comcast.net <br /> April 25, 2019 <br /> Zephyrhills, FL <br /> Attn: Construction Official <br /> Re: Proposed Photovoltaic Solar Panel Installation <br /> Romelio Chirino <br /> 6525 Wagon Trail St. <br /> Zephyrhills,FL 33541 <br /> Dear Plan Reviewer: <br /> Certification: I have reviewed the engineering testing reports for the racking and attachments to <br /> be used on this project and I certify that the products are capable of supporting the code <br /> required loads and are suitable for this installation when installed in strict compliance with the <br /> manufacturers printed instructions. <br /> Regarding the solar panel array installation on the above referenced project please note that <br /> an inspection was performed, and analysis of the existing structure was conducted. There is <br /> adequate structural capacity for the installation of the array with the following <br /> recommendations: <br /> 1. The array will be installed on the existing roof. The roof is constructed of 2"x4" wood trusses <br /> @ 24" O.C. spanning ITT with a top chord length of 217'with intermediate supports at 1/3rd <br /> points making the effective longest span 8'with 1/2" OSB plywood sheathing. The new array <br /> (See Site map by contractor)will add 2.63 Lb./ Sf. overall to the roof.No additional structure <br /> support is required for the existing roof structure. <br /> 2. The system shall be secured to the roof using the"Ecofasten Solar""Rock-IT"®attachment <br /> system. The installation shall be in strict compliance with manufacturers printed instructions. <br /> The attachment system shall be UL 1703 approved tested. The attachments shall be min. 5116" <br /> x 4"long stainless-steel lags with a min. embedment of 3"into the rafters. Attachments shall be <br /> @ 48"o.c. Max. in roof wind zone 1 and @ 24"o.c. Max. in roof wind zone 2 and 3 lags to <br /> alternate rafters. Provide 6 mil. vapor barrier between dissimilar metals. Provide water tight <br /> gasket and sealant at all penetrations. Attachments shall follow panel rows as specified by the <br /> system manufacturer's installation manual. The panel angle shall match the roof slope. <br /> Structural Design Loads per ASCE 7-10 <br /> -Dead Loads= 10 psf(+2.6psf,New Solar Panels)= 12.6 psf.-Live Load=20psf <br /> Total dead weight on attachment= 18Lb. Max. <br /> Ch. 30 Wind Loads Components and Cladding <br /> windloads= 140 mph Exposure B zone 1=+/- 31.4 psf.,Zone 2&3=+/-77.7psf. <br /> Area of Panels largest array=652.68sf <br /> Tributary area panels/attachment max. 652.68sf/ 81min= 8sf. <br /> Min Number of Attachments=81. <br /> Wind pressure 31.4 x Area 652.68/81 No.Attachments=398 <br /> TABLE 10.3.1 NDS Pull out strength of 5/16"x4" lags in rafter=W'=WxCdxCt=2661bs/in <br /> embedment x 3"embedment=798 x1.6Cd xl.00t= 1,276 Lbs Max. >398lbs/attachment OK <br />