Porch Roof Beam Span Table

F stands for the beam s fiber strength in bending which depends on the species of wood.

Porch roof beam span table.

Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. The total load is 4 000 pounds. 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 move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.

A 4 by 10 can usually span up to 12 feet between posts. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Tables 7 12. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Fill in the parts of the formula that are already known. In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts. 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 smallest beams for patio covers are typically 4 by 6. L stands for the span of the beam in feet. The tables below give maximum spans for rafters and beams. For the initial calculation f can be estimated at 1 000.

Download a pdf. Includes size and spacing tables for load bearing and links to related articles. Jan 15 2017 a simple buying guide for beams and rafters that support patio roofs. Tables providing size selections for various beam spans and loading combinations for southern pine dimension lumber and southern pine glued laminated timber are available for the following applications.