These tables can also be used to determine deck joist span.
Max span for 2x12 floor joist.
See our complete chart of floor joist size span and spacing requirements before you build.
True floor joist span calculations can only be made by a structural engineer or contractor.
The maximum span distance for 12 inch spacing is greater by as much as 30 percent compared to 24 inch spacing.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Also available for the android os.
Dead load weight of structure and fixed loads 10 lbs ft 2.
1 ft 0 3048 m.
2 grade of douglas fir are indicated below.
This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.
View joist rafter tables.
Maximum floor joist span for no.
2x10 to 15 feet and 2x12 to 18 feet.
A 2x8 up to 12 feet.
Span calculator for wood joists and rafters also available for the android os.
Joists that are closer together can support more weight which allows the joists to span a longer distance than joists spaced further apart.
The larger the deck the larger the joists.
For example in the joist span table below the highlighted cell shows that 2 x 8 southern yellow pine joists that have a grade of 2 and are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
We ve included 2x6 2x8 2x10 and 2x12 joist spans and more.
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.