Snow Load On A 2 4 Pitch Roof

For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters.

Snow load on a 2 4 pitch roof.

Snow load is the downward force on a building s roof by the weight of accumulated snow and ice. For any rafter the portion of the roof deck that transfers this load is the tributary area. In general determining the pitch of an existing roof is a simple calculation. If you put extra spikes or hangers in the gutters and a gutter cover that will help allow the snow to slide off.

For example a roof with a 6 inch 12 pitch is one where it rises 6 inches vertically for every 12 inches of the horizontal run. This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally. Once again you will need to look at your local charts and use your local snow load factor to determine the maximum span for a given wood rafter size. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are.

Sample maximum roof beam span table feet inches spruce pine or fir no 1 or no 2 with 31 3 psf of snow loading. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Snow will slide off at just about any pitch. How much snow a roof can hold depends on the type of snow roofline and material among other considerations.

If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow. Or if the building was poorly designed or constructed. The roof deck collects the snow load and transfers the weight to the rafters. For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters.

Your best bet is to hold the snow load and let it melt slowly. 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. 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.

Ice damns and fast melts are more a result of air and heat leaving the structure as opposed to exterior melting. The table below shows built up beams for 31 3 psf of snow loading. If you live in the us our snow load calculator compares the total weight on your roof with the permissible load calculated according to the standards issued by the american society of civil engineers regarding the minimum design loads for buildings and other structures asce7 16. These questions aren t quite so easy to answer because there are several variables.