Roof Snow Load Tables

Live loads result from snow and wind.

Roof snow load tables.

In addition the weight of the truss itself acts as a dead load. The sloped roof snow load p s shall be obtained by multiplying the flat roof snow load p f by the roof slope factor c s. In most cases there is less snow on the roof than on the ground. Supporting light frame roof only supporting icf second storey and light frame roof maximum ground snow load kn m2 1 50 3 33 1 50 3 33 140 200 1 41 1 18 1 03 0 93 300 1 78 1 50 1 30 1 18 400 2 08 1 75 1 53 1 38 500 2 33 1.

Snow loads design snow load for a structure is based on the ground snow load for its geographic location expo sure to wind and its thermal geosure to wind and its thermal geo metric and functional charac teristics. This is the snow load calculated in the previous section. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. 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.

The balanced snow. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. The loads are based on adjusted roof snow loads from the governing building code. Dead loads include shingles and sheathing on the top chord and insulation and ceiling finishon the bottom chord.

If your structure has a sloped or flat roof you still need to calculate the flat roof snow load. In most regions the first thing to consider before sizing the wood framing members for a roof is the maximum snow load that the roof will have to bear. For roof live loads less than 20 pounds per square foot psf rafter spans and required e values tabulated for 20 psf shall be permitted to be adjusted in accordance with the fol lowing table. If you live in a region that gets winter snowfall contact your municipal building department to find out what maximum snow loads you.

For roof live loads of 12 psf or 16 psf. Bulb tee purlins 32 5 8 o c 1 2 gypsum board 2 poured gypsum 2 insulation bur. I am a structural engineer in the mid west and have a project that would put snow drift load on an existing structure. The existing roof construction is bar joists 4 0 o c.

After you obtain the roof slope factor from those sections in asce 7 10 the balanced design snow load for the sloped roof can easily be calculated using equation 7 4 1. Roof trusses are designed to carry live and dead loads uniformly on the top and bottom chords.