Cantilever Floor Joist Deck

Conversely a two foot cantilever puts the beam only 12 out well short of the limit.

Cantilever floor joist deck. Unless you like bouncy construction it would be a wise decision to limit the cantilever to about 25 of supported beam or joist length. That s good and it gets better. Section r507 5 notes that deck joists can cantilever up to 1 4 of the joist span. With the allowable cantilever of the joists this beam would support a deck 12 feet by 17 1 2 feet.

Cantilevers offer two other benefits. This will result in the deck feeling solid even when one is standing over the cantilevered ends. Bearing in mind that joist fixings to their supports are likely to be only two skew nails into the bearer a short back span length has the. Cantilevered deck joists h3 2 treated back span cantilever span deck stringer with 12 mm drainage gap 1 5 l l 1 25 l l.

Footnote 6 so cantilevering the joists allows you to build larger decks at lower cost or build stronger decks. Thus the cantilevered deck creates a stiffer platform. The deck plans i recently submitted for a building permit were rejected by the building department s plan reviewer with a note explaining that according to the building code a deck ledger can t be attached to the rim joist of a house with a cantilevered floor. Floor cantilevers constructed in accordance with table r502 3 3 1 shall be permitted where supporting a light frame bearing wall and roof only.

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. An even wiser decision would be to never exceed 3 feet of cantilever in the construction of the deck. In this situation 2x joists should extend back into the floor at least eight feet using a recommended 2 3 ratio. It is possible to extend beyond four feet but each situation must be examined and analyzed for structural capacity.

While it will be years before the 2015 version is widely adopted by local codes many building officials often accept future provisions like these as easy to approve alternatives to costly engineering. 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. I ve mounted deck ledgers to many cantilevered floors in the past without a problem and i ve never heard of a. Many building departments limit joist cantilevers to 24 maximum.

You must use at least five framing nails to attach the rim. Floor cantilevers supporting an exterior balcony are permitted to be constructed in accordance with table r502 3 3 2. 22 build 127 december 2011 january 2012 nzs 3604.