If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.
Porch roof beam span table.
In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
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.
However this seems to match the 6 joist span column of the table.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
In the example the beam spans the 10 foot width of the roof.
Table 9 1 in span tables for joists and rafters figure 5 gives a required compression value of 237 psi for a span of 16 feet and bearing length of 1 5 inches.
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.
View joist rafter tables.
A 4 by 10 can usually span up to 12 feet between posts.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
The tables permit a bearing length of up to 3 5 inches but since 1 5 is probably the worst case that you ll encounter for joist or rafter bearing it s a safe value.
Michael t 5 17 2017 12 53 19 am reply.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts.
Fill in the parts of the formula that are already known.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
Includes size and spacing tables for load bearing and links to related articles.
F stands for the beam s fiber strength in bending which depends on the species of wood.
Download a pdf.
The total load is 4 000 pounds.
The tables below give maximum spans for rafters and beams.
Tables 7 12.
The smallest beams for patio covers are typically 4 by 6.
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.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
For the initial calculation f can be estimated at 1 000.
Jan 15 2017 a simple buying guide for beams and rafters that support patio roofs.
