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GUIDELINES FOR PERMITTING A RESIDENTIAL <br />PHOTOVOLTAIC (PV) SYSTEM <br />SPAN TABLES3: <br />A framing plan is required only if the combined weight of the PV array exceed 5 pounds per <br />square foot (PSF or lbs/ ft2) or, the existing rafters are over -spanned. The following may help <br />determine if the rafters are over -spanned. <br />Use this table for rafter spans that have conventional lightweight dead loads. If there is a roof <br />system that doesn't fall within these tables consider obtaining the advice of a State of Hawaii <br />registered professional Architect or Structural Engineer. <br />Use this table for rafter spans with a ceiling attached, and conventional light dead loads <br />10 PSF Dead Load <br />Roof live <br />load= <br />20 psf, ceiling not attached to rafters, L/A= 180 <br />Rafter Size <br />2 x 4 <br />2 x 6 <br />2 x 8 <br />2x10 <br />2x12 <br />Spacing <br />The measurements below are in feet -inches <br />Species <br />Grade <br />(inches) <br />(e.g. 9-10=9 feet, 10 inches) <br />Douglas <br />42 or <br />16 <br />Fir -larch <br />better <br />9-10 <br />14-4 <br />18-2 <br />22-3 <br />25-9 <br />Douglas <br />42 or <br />24 <br />Fir -larch <br />better <br />8-0 <br />11-9 <br />14-10 <br />18-2 <br />21-0 <br />Use this table for rafter spans with a ceiling attached, and conventional light dead loads <br />If the roof system has: <br />a. Over -spanned rafters or trusses, <br />b. The array is over 5 lbs/ft2 on any roof construction, or <br />c. The attachments with a dead load exceeds 45 lbs per attachment; <br />It is required that you provide one of the following: <br />L A framing plan showing details how you will strengthen the rafters using <br />the supplied span tables. <br />3 The Span Tables and Exhibits A -C were printed with permission from the Solar America Board of Codes & Standards. <br />10 PSF Dead Load <br />Roof live <br />load= <br />20 psf, ceiling not attached to rafters, L/A= 240 <br />Rafter Size <br />2 x 4 <br />2 x 6 <br />2 x 8 <br />2x10 <br />2x12 <br />Spacing <br />The measurements below are in feet -inches <br />Species <br />Grade <br />(inches) <br />(e.g. 9-10=9 feet, 10 inches) <br />Douglas <br />42 or <br />16 <br />Fir -larch <br />better <br />8-11 <br />14-1 <br />18-2 <br />22-3 <br />25-9 <br />Douglas <br />42 or <br />24 <br />Fir -larch <br />better <br />7-10 <br />11-9 <br />14-10 <br />18-2 <br />21-0 <br />If the roof system has: <br />a. Over -spanned rafters or trusses, <br />b. The array is over 5 lbs/ft2 on any roof construction, or <br />c. The attachments with a dead load exceeds 45 lbs per attachment; <br />It is required that you provide one of the following: <br />L A framing plan showing details how you will strengthen the rafters using <br />the supplied span tables. <br />3 The Span Tables and Exhibits A -C were printed with permission from the Solar America Board of Codes & Standards. <br />