Porch Roof Beam Span Chart

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Porch roof beam span chart.

Window door garage door headers supporting roof wall floor loads. Patio roof maximum beam rafter spans. Lumber species southern pine douglas fir douglas fir larch hemlock fir spruce pine fir redwood western cedar ponderosa pine red pine. 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. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. The smallest beams for patio covers are typically 4 by 6. For more information see our disclosures here.

Window door garage door headers supporting roof loads only. This tells you the size of the beam needed to support the porch s roof. Beam span calculator for help simply click on the beside the section you need help with watch this tutorial video. A 4 by 10 can usually span up to 12 feet between posts.

Calculate the initial value for d then round it up to the nearest inch. In the example d calculates to 7 75. If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.