Attic Joist Span

Span exceeds 26 feet in length.

Attic joist span.

Span calculator for wood joists and rafters also available for the android os. Also available for the android os. As mentioned above the span tables within the code list the allowable ceiling joist spans for common lumber sizes based on what design load scenario is applied. True floor joist span calculations can only be made by a structural engineer or contractor.

For uninhabitable attics without storage we will use table r802 4 1 and for uninhabitable attic with limited storage we will use table r802 4 2. Now lets take a look at those tables. Ceiling joist span tables. 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.

It is safe to say though that 2x6 ceiling joists spaced every 24 inches on center a typical arrangement found in attics will not support live loads for a bedroom office or bathroom. Span length is different for every room. So span length and width between the spans can be determined only by calculations.