Porch Roof Beam Span Table

Download a pdf.

Porch roof beam span table.

The tables below give maximum spans for rafters and beams. Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. 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.

Fill in the parts of the formula that are already known. Jan 15 2017 a simple buying guide for beams and rafters that support patio roofs. Michael t 5 17 2017 12 53 19 am reply. The total load is 4 000 pounds.

F stands for the beam s fiber strength in bending which depends on the species of wood. The smallest beams for patio covers are typically 4 by 6. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.

The figures are based on quality materials. A 4 by 10 can usually span up to 12 feet between posts. For the initial calculation f can be estimated at 1 000. However this seems to match the 6 joist span column of the table.

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. If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts. 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. In the example the beam spans the 10 foot width of the roof.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts. In the article it is stated that a 12 joist span corresponds to the double beam span a length equal to the 2x width. View joist rafter tables.

Includes size and spacing tables for load bearing and links to related articles. Tables 7 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.