attaching deck to an existing cantilever floor (residential)

[AskTooMuch]

Can someone link a me a good guide of different methods to do this. I have DCA 6 that says it's not allowed. I've read one method where you make deck bigger than cantilever width and connect the ledger at each end.

 

[hokie66]

Provide separate supports for the deck? That is always my choice for building a deck adjacent to an existing structure.

 

[HouseBoy]

I go along with DCA 6 and I do not "allow" it. I do see it often in existing houses but when I design or replace or there is an upgrade, I do something to frame around the existing cantilever. I THINK that is what you mean when you write "...bigger than the cantilever width..." . Of course with this method, the trimmers are attracting a bigger load and they must be supported (presumably) back at the house wall so.... checking that connection is needed. At best, you have a rim sitting on a plate so the hanger is connected to 1 1/2" material. If you are using an external ledger, that can be tricky also since the cantilever gets in the way of a continuous ledger.
One reason I don't like to support a deck on the rim of a cantilever is "load path". Unless the rim joist is connected to the cantilevered joists with something like an inverted metal hanger, I have to squint too hard to see how the load actually gets to the cantilever joists. I think rim joists are usually just end nailed to the floor joists. Then there is the whole question of how well the cantilevered joists can take the load. Sometimes that is tough to do if there is a decent roof load on the wall.

 

[XR250]

One reason I don't like to support a deck on the rim of a cantilever is "load path". Unless the rim joist is connected to the cantilevered joists with something like an inverted metal hanger, I have to squint too hard to see how the load actually gets to the cantilever joists. I think rim joists are usually just end nailed to the floor joists.

In the past, I have ..
- cut thru the band and supported the deck joists on the wall (and face nailed them to the existing joists)
- added blocking between the joists under the upper wall attached with hangers

This requires more attention to the flashing of course.