Porch Roof Beam Span Chart

Window door garage door headers supporting roof loads only.

Porch roof beam span chart.

Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. This post may contain affiliate links. Fill in the parts of the formula that are already known. Window door garage door headers supporting roof wall floor loads.

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. L stands for the span of the beam in feet. The total load is 4 000 pounds. An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry.

In the example the beam spans the 10 foot width of the roof. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. For the initial calculation f can be estimated at 1 000. The smallest beams for patio covers are typically 4 by 6.

In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts. For more information see our disclosures here. Patio roof maximum beam rafter spans. F stands for the beam s fiber strength in bending which depends on the species of wood.