Porch Roof Beam Span Chart

If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.

Porch roof beam span chart.

In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts. 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. Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. A 4 by 10 can usually span up to 12 feet between posts.

Lumber species southern pine douglas fir douglas fir larch hemlock fir spruce pine fir redwood western cedar ponderosa pine red pine. Patio roof maximum beam rafter spans. This means the example porch would need a 6 inch by 8 inch beam. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.

This post may contain affiliate links. This tells you the size of the beam needed to support the porch s roof. Calculate the initial value for d then round it up to the nearest inch. 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. The smallest beams for patio covers are typically 4 by 6. Window door garage door headers supporting roof loads only.