Attic Joist Spans

Trus joist tji ceiling span roof systems library builder i joists faqs roof truss design of timber structures garage attic ion the journal boardceiling joist and rafter spans home owners.

Attic joist spans.

Live load 30 lbs ft2 1436 n m2 maximum span ft in nominal size. While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. Span length is different for every room. 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.

The width is considerably more important than the thickness of a board. So span length and width between the spans can be determined only by calculations. 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. 1 ft 0 3048 m.

For example the highlighted cell below shows that a 2 x 6 southern yellow pine joist with a grade of 2 and spaced 24 apart can have a maximum span of 10 feet 0 inches 10 0 if you are designing your structure to support a plaster ceiling. Dead load weight of structure and fixed loads 10 lbs ft2. Now lets take a look at those tables. Joist span and spacing is set by your local building code.

1 psf lbf ft2 47 88 n m2. 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. When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. Span exceeds 26 feet in length.

Live load is weight of furniture wind snow and more. For example a joist made from doubled 2 x 6s can span a distance about 25 percent more than a single 2 x 6 but a 2 x 12 can span about 80 percent more than a 2 x 6 even though it has the same amount of wood as a doubled 2 x 6. Ceiling joist spans for common lumber species uninhabitable attics without storage live load 10 psf l δ 240 check sources for availability of lumber in lengths greater than 20 feet.