Snow will slide off at just about any pitch.
Snow load on a 2 4 pitch roof.
How much snow a roof can hold depends on the type of snow roofline and material among other considerations.
For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters.
Snow load is the downward force on a building s roof by the weight of accumulated snow and ice.
If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow.
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.
Or if the building was poorly designed or constructed.
These questions aren t quite so easy to answer because there are several variables.
You can use either 2 6 or 2 4 rafters for roofs with a 3 12 pitch or greater but it depends on the overall size of your shed.
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.
Ice damns and fast melts are more a result of air and heat leaving the structure as opposed to exterior melting.
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.
The roof deck collects the snow load and transfers the weight to the rafters.
It extends outward in.
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.
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.
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.
This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally.
Sample maximum roof beam span table feet inches spruce pine or fir no 1 or no 2 with 31 3 psf of snow loading.
Your best bet is to hold the snow load and let it melt slowly.
If you put extra spikes or hangers in the gutters and a gutter cover that will help allow the snow to slide off.
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.
In general determining the pitch of an existing roof is a simple calculation.
The roof or the entire structure can fail if the snow load exceeds the weight the building was designed to shoulder.
For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters.
