Roof Deck Joists Span

Ready to start calculating how much lumber you ll need for your joists.
Roof deck joists span. The closer the joists are to each other the greater the distance they re able to span safely. Some builders reduce joist spacing to 12 on center to strengthen the deck frame or to increase maximum allowable joist spans. The 2015 irc includes a new table r507 5 deck joist spans for common lumber species. Most decking is not strong enough to support longer spans than 16.
Joist spacing for composite decking. The table makes it easier for deck builders to accurately size deck joists and for inspectors to check decks for adequate framing. Most decks use 16 on center spacing for joists. As a rule the larger the deck the larger the joists.
To learn more about deck joist sizing spacing and allowable span reference this chart. 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. Also available for the android os. Two by twelve douglas fir joists spaced 12 inches apart on center for example can span 20 feet 7.