On multiple factors including.
Sloped roof snow load chart.
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.
Ground snow load pg.
Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.
In order to stay intact and in place a roof must be able to resist loads both permanent and temporary that are pushing.
This information is found in the code book.
The boca code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads.
P s c s p f the thermal factor c t from table e 3 determines if a roof is cold or warm slippery surface values shall be used only where the roof s surface is unobstructed and sufficient space is.
Pent roof is a collection of low mono pitched roofs often seen on residential terraces.
Length of roof downwind of the snow drift.
Wind exposure of roof.
The snow load is treated as a live load when you use af pa s tables.
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.
From eave to ridge w.
It is a traditional roof shape employed everywhere from tropical.
Importance occupancy and use of the building.
Load limits on the roof of a building.
So consider a simple gable roof on a 24 foot wide ranch framed with 2 6 exterior walls and a 1 1 2 ridge.
Roofs are under a lot of pressure.
For dead loads you are correct.
Length of low roof ll.
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.
Horizontal distance from eave to ridge.
This sizing guide for roof rafters will help determine what you need for your small project.
There are several variables to consider when determining the proper rafter size.
Figure 7 1 pages 84 85 and table 7 1 page 92.
Length of roof upwind of the snow drift.
A gable roof is a traditional triangle shaped roof that can range from a medium pitch to sharp angled roofs.
A frame roof is the sharpest gable style roof resembling the shape of the letter a.
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.
Boca also allows you to reduce the snow load for roofs with slopes greater than 30 degrees presumably because snow will slide or blow off steeply pitched roofs.
Ground snow load value.
Roof snow load is defined as the weight of snow on the roof surface used in design of the building structure ibc 2012.
The span would be 11 5 3 4.
