Residential Roof Live Load

The live load on a roof is the weight of any temporary objects on the roof.

Residential roof live load. 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. Cold weather loads snow typically applied to exposed roofs or decks ground snow load commonly 10 psf usually roof live load governs unless snow drifts are considered frost heave condition where soil under footing freezes and exerts upward movement on the foundation bottom of footings must be below frost depth to avoid this. Since it is possible to use the attic for storage the live load of the attic floor is set at 20 psf according to code. Unlike the trussed roof live load and dead load of the rafters and ceiling joists must be accounted for as separate systems.

Where snow isn t a problem the live load can come from people working on the roof and any equipment they take on to the. 1603 1 3 roof snow load. As a result the live load dead load and distribution of forces are different. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated.

1603 1 2 roof live load. Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states. 0 9d 1 0e effect or 0 9 when resisting the load when permanent. 0 9d 1 0w a load factor of 1 6 when adding to load 7.

Minimum uniformly distributed live loads adapted from sei asce 7 10. Further in most areas of the united states design winds are produced by either hurricanes or. 1607 12 1 distribution of roof loads. This issue of live load vs.

Minimum design loads for buildings and other structures location uniform load psf kn m2 apartments see residential access floor systems office use. The roof live load used in the design shall be indicated 780 cmr 1607 11. Axial forces from snow loads and roof live loads should usually not be considered simultaneously with an extreme wind load because they are mutually exclusive on residential sloped roofs. The ground snow load p gf and the flat roof snow load p and if applicable the sloped roof snow load p s shall.

Design loads for residential buildings 3 1 general.