Minimum Roof Slope For Snow Load

All commercial buildings and structures should use the ground snow load values from the 2009 ibc and not the residential design values given below.

Minimum roof slope for snow load.

If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow. 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. When it comes to residential construction your roof is a visible part of the structure.

In general determining the pitch of an existing roof is a simple calculation. Suitable materials for pitched roofs. You multiply it by whatever equation 7 1 gives you. Minimum pitch for corrugated metal roof.

All snow loads acting on a sloping surface shall be considered to act on the horizontal projection of that surface. The slope roof snow load p s shall be obtained by multiplying the flat roof snow load pf by the roof slope factor cs. Roof design snow loads derived from figure 321 02 of the wisconsin. Values of c s for warm roofs and cold roofs are as.

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. 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.

B sloped roof snow loads ps. Btw i think there is some confusion on what i m saying about the 7 factor. 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. Keep in mind that neither metal shingles not corrugated metal panels are suitable options for low slope or nearly flat roofs.

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. Okay i just got the word from a highly placed source that the minimum snow load provision only applies to low slope roofs. Pitched roofs begin with with slopes greater than 3 in 12. 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.

So you do not multiply cs by the minimum pf for sloped roofs. When the roof slope is greater than 5 the roof is considered sloped. Steeper slopes are ideal for areas that have higher snow loads and will also prevent the possibility of ponding water on the roof. P s cspf equation 68 5 3.

According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal.