Residential Roof Snow Loads

How snow load can damage your buildings.

Residential roof snow loads.

Or if the building was poorly designed or constructed. The roof or the entire structure can fail if the snow load exceeds the weight the building was designed to shoulder. If the snow weighs 10 pounds per cubic foot and there are 1 5 feet on the roof each square foot of the roof is getting 15 pounds of pressure. Snow load is the downward force on a building s roof by the weight of accumulated snow and ice.

The live load on a roof is the weight of any temporary objects on the roof. 0 9d 1 0w a load factor of 1 6 when adding to load 7. On the upcodes website. This issue of live load vs.

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. Victor staley a building official in the town of brewster mass responds. Overestimation of snow loads can unnecessarily increase the cost of construction.

To figure out the load on your roof take the depth of snow in feet and multiply it by the weight of a cubic foot of snow. 7 2b with a c s 1 0 p f flat roof snow load in psf. 7 4 1 7 4 4 and asce figure 7 2 below. 0 9d 1 0e effect or 0 9 when resisting the load when permanent.

Where snow isn t a problem the live load can come from people working on the roof and any equipment they. P s sloped roof snow load in psf c s roof slope factor as determined by asce sec. Chapter 16 structural design. 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 roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. 2018 international building code. Minimum uniformly distributed live loads adapted from sei asce 7 10. Snow loads are influenced by elevation general weather and moisture patterns slope direction exposure roof or trail bridge configuration and wind direction and severity.

Calculate unbalanced snow load for hip and gable roofs as shown in asce figure 7 5 below. Simple design check representative of worst case combined axial and transverse loading. Residential roof with asphalt wood shingles or shakes would use fig.