What is snow load psf?
The state’s building code requires residential roofs withstand snow loads of at least 30 pounds per square foot. The trick is determining the weight per square foot of whatever combination of snow, ice, slush and water has piled onto your roof. If it’s more than 30 pounds, the roof could collapse.
What is a good snow load rating?
5-20 for light snow. 20-40 for packed snow. 40-58 for packed snow with ice. 58 for ice.
How is psf snow load calculated?
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. 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.
What is a typical snow load?
The maximum snow load of your roof depends on several factors, but the average roof can support about 20 pounds of snow per square inch. However, some areas of the U.S. that are prone to lots of snow may have roofs that support a heavier snow load.
Is snow load a dead load?
There are two types of loads in construction: live loads and dead loads. Ever-changing live loads like snow and ice are temporary weights on the structure. Dead loads are all the permanent parts of the building that add to the weight of the structure.
What is roof load psf?
Roof loads are measured by pounds per square foot. The dead load of asphalt shingle roofs with wooden frames is usually 15 pounds per square foot (psf). Heavier residential roofing materials such as clay and slate have dead loads that reach up to 27 psf.
What pitch roof is best for snow?
Roofs in snowy climates should have a slope of at least a 10-degree pitch minimum. A steeper angled roof sheds the snow more quickly. While the angle of the roof helps shed snow, adding too many angles to the roof for a more aesthetic effect could cause structural problems with snow shedding in the wintertime.
What does 30 lb snow load mean?
This downward imposed load on the home is also known as the snow load. The North Zone design live load equates to 40 pounds per square foot, the Middle Zone equates to 30 pounds per square foot, and the South Zone equates to 20 pounds per square foot.
Is snow load a live load?
Live loads are those loads produced by the use and occupancy of a building or structure and do not include construction loads, environmental loads (such as wind loads, snow loads, rain loads, earthquake loads and flood loads) or dead loads (see the definition of “Live Load” in IBC 202).
Is snow a dead load?
These could include seismic activity, wind, rain, and snow. They are considered separate from live or dead loads because they may act laterally on a structure (whereas other loads act vertically). Other factors that would be considered environmental loads include wind, soil movement, and other environmental conditions.
Does roof pitch affect snow load?
A roof with an especially steep roof pitch can still develop dangerous snow loads. That’s because virtually all roofs have valleys, inclusions, or structural obstructions that will disrupt snow shedding.
How much snow can a 4/12 pitch roof handle?
Most roofs can withstand 20 pounds per square foot of snow. 2. Calculate the weight of the snow on your roof. Ten inches of fresh snow equates to about five pounds per square foot, which means your roof likely can support four feet of fresh snow.