Roof Live Load Psf

3 20 residential structural design guide.

Roof live load 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. In areas where the ground snow load is less than 15 psf the minimum roof live load refer to section 3 4 is usually the controlling rgavity load in roof design. 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 loads are a downward vertical force on the home.

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. This downward imposed load on the home is also known as the snow load. Roof load live load design is affected by the shape of the roof whether it is flat curved or pitched. Minimum design live load can be found in asce 7 table 4 1 or ibc table 1607 1.

To correctly apply the values of the tables and the prescriptive methods of construction build ers must know the structural design criteria in the planning chapter of the code. The uniform design live load in unoccupied landscaped areas on roofs shall be 20 psf 0 958 kn m 2. The uniform design live load for occupied landscaped areas on roofs shall be determined in accordance with table 1607 1. Roof and floor live loads are produced during maintenance by workers equipment and materials and during the life of the structure by movable objects such as planters and people.

Gridirons over stages shall be designed to support a uniformly distributed live load of 50 psf 2 40 kn m 2 in addition to the rigging loads indicated. 1607 13 4 awnings and canopies. 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. 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 a larger map with greater detail refer to asce 7 98. Chapter 3 design loads for residential buildings. 6 2015 home builders jobsite codes note the roof is designed for the roof live load not more than 20 psf or the snow load whichever is greater. 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.