2x8 Floor Joist Cantilever

With the allowable cantilever of the joists this beam would support a deck 12 feet by 17 1 2 feet.

2x8 floor joist cantilever.

At the line of the cantilever support wall. I think 3 ft would be okay. Cantilevered joists in an enclosed space. 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.

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. 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. Many building departments limit joist cantilevers to 24 maximum. Section r507 5 notes that deck joists can cantilever up to 1 4 of the joist span.

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. Using stiffer lumber types such as yellow pine douglas fir or hemlock would add stiffness. An example of this would be a joist that spans 10 feet between supports. 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.

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. Thus a 10 4 14 foot joist would be possible. 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. The back span of the sistered joists is in a two thirds ratio to the bump out or 7 ft.

Any more and it may be bouncy. Cantilevered floor joists h1 2 treated l. Branz recommends that all cantilevered joists have continuous blocking. You must use at least five framing nails to attach the rim joist to the ends of your joists.

Cantilevers perpendicular to joist direction. Yellow pine is widely available in treated lumber. The outside cantilevered joists are doubled as is the rim joist. Code says 2ft cantilever can be done with 2x8 joists.