in typical deck construction, with a ledger on one side of the joist and beam on the other, the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above. for best results, refer to our wood and composite deck joist span table.
sizing deck beams got a lot easier with the publication of the 2015 international residential code. deck builders can now refer to section r507.6 deck beams and table r507.6 deck beam span lengths to determine the size of 2-ply and 3-ply built-up beams made from 2×6 through 2×12 lumber.
deck cantilevers. section r507.5 notes that deck joists can cantilever up to 1/4 of the joist span. but you’ll notice when you look at the portion of the span table for joists with cantilevers that the joist span for decks with a cantilever is often less than the span for the same sized joist without cantilevers.
when supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. a double 2x12 beam can span 12 feet; a 2 2x10 can span 10 feet and so on. dimensional lumber deck beam span chart . the numbers in gray indicate the distance between the support posts.
although the practice is common, there’s no allowance for interpolating beam spans when the joist length you’re dealing with isn’t listed in the table. for example, a double 2×8 beam can span 8-ft.-0 in. when the deck joists are 6 ft. long. when the deck joists are 8 ft. long, the beam can span 7-7.
the distance you can span a 2-by-10 joist without additional support depends on the species and grade of the wood, how far apart the joists are and the expected load on the joists. how far can you span a 2x10 floor joist? hunker may earn compensation through affiliate links in this story.
how to compute the spans for a deck how to compute the spans for a deck. building a deck? then you'll need to know how to compute the spans. find tips and information on lumber types, decking, standard lengths, and more. 16' span: 16 1/2' joist: 2x10 if joists are spaced: 24' span: 13 1/2' decking. decking boards span from joist to joist