Most decks use 16 on center spacing for joists.
Roof deck joists span.
Most decking is not strong enough to support longer spans than 16.
The 2015 irc includes a new table r507 5 deck joist spans for common lumber species.
Also available for the android os.
The table makes it easier for deck builders to accurately size deck joists and for inspectors to check decks for adequate framing.
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.
Ready to start calculating how much lumber you ll need for your joists.
Some builders reduce joist spacing to 12 on center to strengthen the deck frame or to increase maximum allowable joist spans.
To learn more about deck joist sizing spacing and allowable span reference this chart.
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.
Joist spacing for composite decking.
As a rule the larger the deck the larger the joists.
Span calculator for wood joists and rafters also available for the android os.