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.
Minimum roof slope for snow load.
Roof design snow loads derived from figure 321 02 of the wisconsin.
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.
In case a slope greater than this is necessary then a double underlayment application must be used as per the requirements of the international building code.
The sloped roof snow load is calculated using equation 7 4 1.
B sloped roof snow loads ps.
When it comes to residential construction your roof is a visible part of the structure.
This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally.
Keep in mind that neither metal shingles not corrugated metal panels are suitable options for low slope or nearly flat roofs.
Btw i think there is some confusion on what i m saying about the 7 factor.
You can click on the map below to find the minimum roof design snow load for that location.
A minimum pitch of 3 in 12 or even 4 in 12 will normally be required.
So you do not multiply cs by the minimum pf for sloped roofs.
Pitched roofs begin with with slopes greater than 3 in 12.
The slope roof snow load p s shall be obtained by multiplying the flat roof snow load pf by the roof slope factor cs.
Okay i just got the word from a highly placed source that the minimum snow load provision only applies to low slope roofs.
Values of c s for warm roofs and cold roofs are as.
If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow.
Minimum pitch for corrugated metal roof.
According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal.
Sloped roof snow loads are assumed to be acting on the horizontal projection of the surface.
A steep slope roof is one whose slope is greater than 3 12.
All snow loads acting on a sloping surface shall be considered to act on the horizontal projection of that surface.
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.
When the roof slope is greater than 5 the roof is considered sloped.
You multiply it by whatever equation 7 1 gives you.
Steeper slopes are ideal for areas that have higher snow loads and will also prevent the possibility of ponding water on the roof.
In general determining the pitch of an existing roof is a simple calculation.
P s c s p f.
All commercial buildings and structures should use the ground snow load values from the 2009 ibc and not the residential design values given below.
