Before building a composite deck always read the installation instructions from the manufacturer paying.
Roof deck joists span.
For example joists spaced 16 inches from the center of the joist next to it can span 1 5 times in feet the depth of their inches.
Ready to start calculating how much lumber you ll need for your joists.
The closer the joists are to each other the greater the distance they re able to span safely.
Span tables f7 rafters 30mm 11 f7 rafters 42mm 14 verandah beams f7 42mm sheet roof 17 verandah beams f7 42mm tile roof 20 verandah beams gl8 sheet roof 21 verandah beams gl8 tile roof 24 ridge beams f7 42mm sheet roof 25 ridge beams f7 42mm tile roof 28 internal floor joists f7 42mm 30.
Joist spacing for composite decking.
As a rule the larger the deck the larger the joists.
Two by twelve douglas fir joists spaced 12 inches apart on center for example can span 20 feet 7.
The 2015 irc includes a new table r507 5 deck joist spans for common lumber species.
Also available for the android os.
Most decking is not strong enough to support longer spans than 16.
Most decks use 16 on center spacing for joists.
Span calculator for wood joists and rafters also available for the android os.