Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
Flat roof wooden beam.
In the warm flat roof construction there is insulation packed into every possible space where air can flow.
The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Also available for the android os.
After the roof is framed plywood sheathing is installed for the roofing.
On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases.
Wooden beams attach atop the posts and rafters install between the beams.
Span calculator for wood joists and rafters also available for the android os.
The major difference between the warm flat roof and the cold flat roof has to do with the air flow between the roofing timbers known as joists that help to hold up the roof.
For a flat roof with snow loading this is 25 lbs.
This is a completion video of a flat roof framing.
This is a completion video of a flat roof framing.
Calculate the weight the beam must support.
Steel is cheaper than wood in most cases and it can handle a load much better but steel beams must usually be cut off site and trucked into a location whereas wood beams can readily be cut on site.
For rooms which are heavily frequented it may be 50 lbs.
The size of lumber used depends on the size of.
Multiply the loading per square foot by the area in square feet of the surface which the beams will be supporting.
Per square foot for northern areas of the u s.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.