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ENGINEERED POWER SOLUTIONS <br />72 SOUTH MAIN STREET, SUITE A <br />TEMPLETON, CA 93465 <br />Solar Warehouse Rail Analysis – Generic Packet <br />3.4 – Ground Snow Load Capacity <br />It is the responsibilty of others to confirm that the existing building was designed <br />correctly for the site specific design snow loads per the governing building code. The <br />addition of a new rooftop PV system (mounted flush with the roof) does not change <br />the amount of snow that falls on the roof but it can change how the snow load is <br />distributed to the roof as the modules transfer the snow loads as numerous point <br />loads through the anchorage points rather than an area load over the roof. The <br />adequacy of the existing structure to support the PV loads (including changes to how <br />the snow load is distributed) shall be checked by a registred licensed engineeer as it <br />is not the responsibility of EPS. <br />The design Roof Live Load is interchangeable with the design Roof Snow Load as <br />noted in the load combinations. The point loads (uplift and downward) transferred <br />by the PV racking system to the building’s structural support system shall be <br />evaluated by a registred licensed engineer during the building evaluation (not per <br />EPS). Downward loads shall be calculated on a site by site basis by the engineering <br />responsibily for justifiying the building adequacy. If the calculated downward loads <br />at the maximum allowable span is determined to be in excess of the allowable <br />capacity of the building, shorter rail spans between anchors may be required to more <br />evenly distribute the downward loads to the existing building (per building <br />engineer). <br />The sloped roof snow load (ps) is determined as follows: <br />• ps = pf*Cs Eq. 7.4-1 <br />o Flat Roof Snow Load pf = 0.7*Ce*Ct*I*pg Eq. 7.3-1 <br />▪ Exposure Factor Ce: 1.0 Table 7-2 <br />▪ Thermal Factor Ct: 1.2 Table 7-3 <br />▪ Snow Importance Factor (I): Table 1.5-2 <br />• 1.00 used in all cases <br />o Cs = 1.00 for tilts of 0° to 27° or 0.78 for tilts of 27° to 45° <br />Example Scenario Calculation: <br /> Sloped Roof Snow = 1.00*pf <br />Where pf = 0.7*1.0*1.2*1.00*30 psf = 25.2 psf <br /> Snow Load per Rail = 25.2 psf. * 3.25 ft. = 81.9 plf <br />Page 69 <br />2004 W Picasso - <br />2018062008/29/23