Roof Live Load Less Than 20

On a roof with a slope greater than 4 to 12 the live load limit is typically adjusted downward from 20 psf to 15 psf to allow for the relatively greater dead load on the steeper roof.

Roof live load less than 20. Af pa s appendix a lists a variety of live and dead load combinations for floors ceilings and rafters. Factors that influence. 1607 12 1 distribution of roof loads. For example appendix a indicates that one type of clay tile roof system has a live load value of 20 psf and a dead load value of 15 psf.

R 1 1 for a t less than or equal to 200 psf r 1 1 2 0 001 a t for between 200 psf and 600 psf. For roof live loads of 12 psf or 16 psf. The loads are based on adjusted roof snow loads from the governing building code. R 1 0 6.

Where l r shall not be less than 12 psf and not more than 20 psf. In my region on cape cod we have a ground snow load design of 25 psf which is a greater design load than the live load 12 psf to 20 psf over an entire roof system. Roof live load may be reduced by the following equation. Many factors influence how a system responds to loading.

L r l o r 1 r 2. In other words on a steep roof less material would be stacked in a concentrated area at one time to avoid having it slide off. Where uniform roof live loads are reduced to less than 20 psf 0 96 kn m 2 in accordance with section 1607 13 2 1 and are applied to the design of structural members arranged so as to create continuity the reduced roof live load shall be applied to adjacent spans or to alternate spans whichever produces the most unfavorable load effect see section 1607 13 2 for reductions in minimum roof. Where uniform roof live loads are reduced to less than 20 psf 0 96 kn m 2 in accordance with section 1607 12 2 1 and are applied to the design of structural members arranged so as to create continuity the reduced roof live load shall be applied to adjacent spans or to alternate spans whichever produces the most unfavorable load effect.