Minimum Roof Slope For Snow Load

A steep slope roof is one whose slope is greater than 3 12.

Minimum roof slope for snow load.

Roof design snow loads derived from figure 321 02 of the wisconsin. P s cspf equation 68 5 3. Btw i think there is some confusion on what i m saying about the 7 factor. The sloped roof snow load is calculated using equation 7 4 1.

All snow loads acting on a sloping surface shall be considered to act on the horizontal projection of that surface. If your roof is 1 000 square feet the total snow load is 15 000 pounds of snow. All commercial buildings and structures should use the ground snow load values from the 2009 ibc and not the residential design values given below. So you do not multiply cs by the minimum pf for sloped roofs.

Steeper slopes are ideal for areas that have higher snow loads and will also prevent the possibility of ponding water on the roof. 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. Okay i just got the word from a highly placed source that the minimum snow load provision only applies to low slope roofs. B sloped roof snow loads ps.

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. P s c s p f. This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally. 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.

A minimum pitch of 3 in 12 or even 4 in 12 will normally be required. In general determining the pitch of an existing roof is a simple calculation. The slope roof snow load p s shall be obtained by multiplying the flat roof snow load pf by the roof slope factor cs. Minimum pitch for corrugated metal roof.

When the roof slope is greater than 5 the roof is considered sloped. Suitable materials for pitched roofs. You multiply it by whatever equation 7 1 gives you. Keep in mind that neither metal shingles not corrugated metal panels are suitable options for low slope or nearly flat roofs.

According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal. 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. When it comes to residential construction your roof is a visible part of the structure. Sloped roof snow loads are assumed to be acting on the horizontal projection of the surface.

Values of c s for warm roofs and cold roofs are as.