Span calculator for wood joists and rafters also available for the android os.
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.
To learn more about deck joist sizing spacing and allowable span reference this chart.
Ready to start calculating how much lumber you ll need for your joists.
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.
Most decking is not strong enough to support longer spans than 16.
Two by twelve douglas fir joists spaced 12 inches apart on center for example can span 20 feet 7.
Some builders reduce joist spacing to 12 on center to strengthen the deck frame or to increase maximum allowable joist spans.
As a rule the larger the deck the larger the joists.
Before building a composite deck always read the installation instructions from the manufacturer paying.
Also available for the android os.
Joist spacing for composite decking.
The 2015 irc includes a new table r507 5 deck joist spans for common lumber species.