Frameing For Roof Loads

Consult local building codes for snow load capacity and reference the span tables for joists and rafters published by the american wood council awc as a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24.

Frameing for roof loads.

There are several roof types. It is important to list live load dead load and total load separately because live load is used to compute stiffness and total load is used to calculate strength. The dead load of a typical asphalt shingled wood framed roof is about 15 pounds per square foot. 15 psf x 14ft 210 pounds per lineal foot.

All roof framing tables are organized by maximum snow load. However if the attic is intended for storage the attic live load or some portion should also be considered for the design of. The dead load on a roof includes the framing sheathing and roofing. If you live in a region that gets winter snowfall contact your municipal building department to find out what maximum snow loads you need to design for.

Converting a flat roof to a pitched roof is essentially framing a new roof for an average of 6 to 9 per square foot. The gable roof hip roof gambrel roof flat roof shed roof mansard roof and many more custom roof types. Detailed flat to pitched roof conversion costs. Roof framing depends on the type of roof you want to build.

For dead loads you are correct. 50 psf x 14ft 700 pounds per lineal foot. The load increases with the use of heavier roofing material. Let s look at the sample table below which shows maximum rafter spans for a snow load of 31 3 pounds per square foot psf.

The boca code recognizes this and allows you to use the horizontal projection of the roof when calculating snow loads. 2attic loads may be included in the floor live load but a 10 psf attic load is typically used only to size ceiling joists adequately for access purposes. A dead load is the permanent non movable loading force exerted on the roof framing by the weight of the structure itself. 910 pounds per lineal foot.

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. A clay tiled roof may have a dead load. Depending on your region you may need to design for a maximum snow load of anything between zero to 65 pounds per square foot or roughly 0 3 kpa.