Roof Live Load Tables

You must determine the snow load for your region.

Roof live load tables.

The fact that snow loads only act part of the year has been used to create the rafter tables. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. 1607 10 1 basic uniform live load reduction. Load types loads used in design load equations are given letters by type.

Uniform live loads at roofs are permitted to be reduced in accordance with section 1607 12 2. L o unreduced roof live load per square foot m 2 of horizontal projection supported by the member see table 1607 1. 1 for garages. If your code book says your snow load is 40 psf then you use the 40 psf live load rafter table.

D dead load l live load l r live roof load w wind load s snow load e earthquake load r rainwater load or ice water load. Roof live loads largest roof loads typically caused by repair and maintenance pitch rise span lr 20 r1r2 12 lr 20 lr horizontal projection roof live load 16 r 1 r 2 live load reduction factors r 1 accounts for size of tributary area of roof column a t r 2 effect of the roof rise. The fact that snow loads only act part of the year has been used to create the rafter tables. Compression perpendicular to the grain.

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. Except for uni form live loads at roofs all other minimum uniformly distrib uted live loads lo in table 1607 1 are permitted to be reduced in accordance with section 1607 10 1 or 1607 10 2. Loads should be determined in accordance with this chapter. Floors in garages or portions of buildings used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of table 1607 1 or the following concentrated loads.

For roof live loads of 12 psf or 16 psf table multiply tabulated multiply required number span by e value by 12 psf 16 psf 12 psf 16 psf. This information is found in the code book. L r reduced roof live load per square foot m 2 of horizontal projection supported by the member. The reduction factors r 1 and r 2 shall be determined as follows.

However if the attic is intended for storage the attic live load or some portion should also be considered for the design of. The snow load is treated as a live load when you use awc s tables. Equation 16 27 equation 16 28. 1 inch 25 4 mm 1 square inch 645 16 mm 2 1 pound per square foot 0 0479 kn m 2 1 pound 0 004448 kn 1 pound per cubic foot 16 kg m 3.

The snow load is treated as a live load when you use af pa s tables. 2attic loads may be included in the floor live load but a 10 psf attic load is typically used only to size ceiling joists adequately for access purposes. Used but they typically defined the load cases or combination stress or strength limits and deflection limits.