Roof Live Load Less Than 20

Roof live load of 20 psf or less see ibc 1607 and chapter 3 of this publication r rain load see ibc 1611 and chapter 3 of this publication s snow load see ibc 1608 chapter 7 of asce sei 7 and chapter 4 of this publication t cumulative effects of self straining forces and effects see asce sei 2 3 4 and 2 4 4 w load due to wind pressure see ibc.

Roof live load less than 20.

R 1 0 6. Many factors influence how a system responds to loading. Where l r shall not be less than 12 psf and not more than 20 psf. For roof live loads of 12 psf or 16 psf.

1607 12 1 distribution of roof loads. Where uniform roof live loads are reduced to less than 20 psf 0 96 kn m2 in accordance with section 1607 12 2 1 and are applied to the design of structural members arranged so as to create continulty the reduced roof live load shall be applied to adjacent spans or to alternate spans whichever produces. 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. Factors that influence.

Roof live load may be reduced by the following equation. L r l o r 1 r 2. 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. The loads are based on adjusted roof snow loads from the governing building code.

Af pa s appendix a lists a variety of live and dead load combinations for floors ceilings and rafters. 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. 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. For roof live loads less than 20 pounds per square foot psf rafter spans and required e values tabulated for 20 psf shall be permitted to be adjusted in accordance with the fol lowing table.