Roof Live Load

Chapter 3 design loads for residential buildings.

Roof live load.

Where snow isn t a problem the. The dead load on a roof is the weight of the roof structure itself along with any permanently attached. It the roof is subjected to snow load it should be designed for the actual load due to snow or lot the live loads specified in table 1 3 whichever is more severe. The live load on a roof is the weight of any temporary objects on the roof.

Minimum design live load can be found in asce 7 table 4 1 or ibc table 1607 1. This downward imposed load on the home is also known as the snow load. Roofs of buildings used for promenade or incidental assembly purposes shall be designed for a minimum load of 400 kg m2 4 kn m2 or heavier it required. 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. And each case shall be treated on its own merits. For a larger map with greater detail refer to asce 7 98. 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.

Using the term live loads when referring to roofs might make you scratch your head initially because roofs unlike floors aren t asked to bear the weight of things such as furniture and occupants of a home what you would normally think of as a live load. The north zone middle zone and the south zone are identified on the roof load zone map above. Roof load live load design is affected by the shape of the roof whether it is flat curved or pitched. Loads used in design load equations are given letters by type.

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 the most unfavorable load effect. Live roof load w wind load s snow load e earthquake load r rainwater load or ice water load t effect of material temperature h hydraulic loads from soil f hydraulic loads from fluids. Roof loads are a downward vertical force on the home. Actual load due to snow will depend upon the shape of the roof and its capacity to retain the snow.

The uniform design live load in unoccupied landscaped areas on roofs shall be 20 psf 0 958 kn m 2.