Porch Roof Beam Span Chart

Calculate the initial value for d then round it up to the nearest inch.

Porch roof beam span chart. The smallest beams for patio covers are typically 4 by 6. Window door garage door headers supporting roof loads only. Beam span calculator for help simply click on the beside the section you need help with watch this tutorial video. 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. Window door garage door headers supporting roof wall floor loads. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. 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.

This means the example porch would need a 6 inch by 8 inch beam. Lumber species southern pine douglas fir douglas fir larch hemlock fir spruce pine fir redwood western cedar ponderosa pine red pine. For more information see our disclosures here. In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts.

A 4 by 10 can usually span up to 12 feet between posts. If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts. This tells you the size of the beam needed to support the porch s roof.