Residential Roof Live Load

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.

Residential roof live load.

Unlike the trussed roof live load and dead load of the rafters and ceiling joists must be accounted for as separate systems. Victor staley a building official in the town of brewster mass responds. The ground snow load p gf and the flat roof snow load p and if applicable the sloped roof snow load p s shall. 0 9d 1 0w a load factor of 1 6 when adding to load 7.

0 9d 1 0e effect or 0 9 when resisting the load when permanent. Design loads for residential buildings 3 1 general. Minimum uniformly distributed live loads adapted from sei asce 7 10. 1607 12 1 distribution of roof loads.

Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states. Minimum design loads for buildings and other structures location uniform load psf kn m2 apartments see residential access floor systems office use. The live load on a roof is the weight of any temporary objects on the roof. As a result the live load dead load and distribution of forces are different.

This issue of live load vs. 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. 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. Applied shall be indicated.

The roof live load used in the design shall be indicated 780 cmr 1607 11. 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. 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. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated.

1603 1 3 roof snow load.