2x8 Floor Joist Cantilever

Yellow pine is widely available in treated lumber.

2x8 floor joist cantilever.

Theoretically it could cantilever 40 x 10 4 feet beyond the supporting beam. I think 3 ft would be okay. Cantilevered joists in an enclosed space. Code says 2ft cantilever can be done with 2x8 joists.

The back span of the sistered joists is in a two thirds ratio to the bump out or 7 ft. With the allowable cantilever of the joists this beam would support a deck 12 feet by 17 1 2 feet. But if the joist is a 2x8 with an actual width of 7 25 inches then the cantilever would be limited to 4 x 7 25 29 inches. Because existing floor joists ran parallel to the bump out it was possible to sister 2x8 douglas fir joists to the existing floor joists to create the cantilever.

With triforce it is possible to construct a cantilever perpendicular to the joists by using 2x joists inserted through the open webs of the joists. Many building departments limit joist cantilevers to 24 maximum. Using stiffer lumber types such as yellow pine douglas fir or hemlock would add stiffness. The outside cantilevered joists are doubled as is the rim joist.

But you ll notice when you look at the portion of the span table for joists with cantilevers that the joist span for decks with a cantilever is often less than the span for the same sized joist without cantilevers. Element in the storey below in which case blocking is required by clause 7 1 2 1 of nzs 3604 2011 and figure 7 2. Thus a 10 4 14 foot joist would be possible. Cantilevered floor joists h1 2 treated l.

The distance your joists can safely cantilever or overhang a drop beam is determined by the size of the joists the wood type and grade of the lumber and the spacing between joists. Branz recommends that all cantilevered joists have continuous blocking. Any more and it may be bouncy. At the line of the cantilever support wall.

A southern pine 2 2x12 beam can span 8 feet when supporting joists spanning a maximum of 14 feet and it can cantilever 2 feet beyond the posts on each side. If the cantilever is being extended from the trimmable i joist end of a triforce joist a 5 8 wood filler is required on the osb panel. You must use at least five framing nails to attach the rim joist to the ends of your joists. Cantilevers perpendicular to joist direction.