What is the snow load for Massachusetts?
780 CMR Commercial Mass State Building Code Table 1604.11 provides snow load for roofs. The Ground Snow Load ranges from 45 lbs to 65 lbs per horizontal square foot depending on each community and the zone in which it is located.
What is snow load psf?
Collect and weigh 1 cubic foot of snow (1 foot high x 1 foot wide x 1 foot long). Then estimate or measure snow depth on the roof. If your cubic foot of snow weighs 11 lbs and you have 2 feet of snow on the roof, then you have about 22 psf of snow load on your roof.
How does roof pitch affect snow load?
For example, if a roof’s angle rises four inches every foot, its pitch is commonly denoted as ‘4/12’. It stands to reason that a steeper roof is going to do a better job at shedding snow. And, the faster snow naturally falls off the roof, the less time it will have to build up and create a potential problem.
What is a typical snow load?
The state’s building code requires residential roofs withstand snow loads of at least 30 pounds per square foot. That type of load, says Town of Suffield Building Official Ted Flanders, takes 4 feet of fluffy snow, 2 feet of dense snow or about six inches of water.
Are snow guards required by code?
Snowpack, or the buildup of snow and ice, on any roof can produce significant sliding forces. In most alpine regions of Europe and Scandinavia, the use of snow-guard systems is mandated by building authorities, however such policy in North America is quite rare and only required by local code authorities if at all.
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.
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.
Is a 3/12 roof pitch good for snow?
Roof pitches of 3:12, 4:12, 5:12, or 6:12 work best for metal buildings in snow country. Anything over a 6:12 pitch tends to make massive amounts of snow slide off the roof without warning. Anything less than 1:12 pitch is a huge mistake in snow-prone climates.
Is snow load live or dead?
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).
How many snow guards do I need?
Use: 2 snow guards per valley for every 8 feet of roof. Snow load: Up to 45 PSF ground snow load. Starting at 6 inches from the bottom edge, place 2 snow guards equally spaced apart in the valley, in a staggered pattern, across the entire roof area.
How to calculate ground snow loads in Massachusetts?
Massachusetts Ground Snow Loads TM. Use our Massachusetts Ground Snow Loads map to easily determine the ground snow load (Massachusetts State Building Code: 780 CMR 51.00) for any location in the State of Massachusetts. You can click on the map below to find the design ground snow load for that location. The 8th Edition Massachusetts…
Which is greater a snow load or a live load?
In my region on Cape Cod, we have a ground snow load design of 25 psf, which is a greater design load than the live load (12 psf to 20 psf) over an entire roof system. The bottom line is that the IRC requires you to design the roof structure to the greater roof load, and in my region, that’s the ground snow load.
When to use ground snow load in roof design?
In areas where the ground snow load, Pg, exceeds 10 pounds per square foot (psf) (0.479 kN/m 2 ), the following additional information shall also be provided, regardless of whether snow loads govern the design of the roof: Flat-roof snow load, Pf. Snow exposure factor, Ce.
How is seismic design determined in Ma building code?
The jurisdiction shall fill in this part of the table with the seismic design category determined from Section R301.2.2.1.