Roof Live Load Psf

3 20 residential structural design guide.

Roof live load 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. 1607 13 4 awnings and canopies. 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. Minimum design live load can be found in asce 7 table 4 1 or ibc table 1607 1.

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. 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. 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.

The north zone middle zone and the south zone are identified on the roof load zone map above. 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. Roof load live load design is affected by the shape of the roof whether it is flat curved or pitched.

1607 3 uniform live loads the live loads used in the design of buildings and other structures shall be the maximum loads expected by the intended use or occupancy but shall in no case be less than the minimum uniformly distributed unit loads required by table 1607 1. 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. The uniform design live load for occupied landscaped areas on roofs shall be determined in accordance with table 1607 1. The uniform design live load in unoccupied landscaped areas on roofs shall be 20 psf 0 958 kn m 2.

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. For a larger map with greater detail refer to asce 7 98. 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. This downward imposed load on the home is also known as the snow load.