Cantilevered Wood Floor Joists

[TRAK.Structural]

See sketch below. I have a situation where I'm trying to extend the interior space of a residential structure by cantilevering the ground level first floor joists (apprx 2' cantilever and 11' backspan). There are similar "bumpouts" to this on the home already, so the goal is to just make the exterior wall all in the same plane along this elevation and recapture some interior space.

Firstly, do these joists need to be pressure treated? I can't find anything specific in the code for this. Seems similar to a roof overhang where the rafters would typically NOT be treated; but it is obviously much closer to the ground which could be likened to joists in the crawl space that need a minimum distance from ground to NOT be pressure treated.

Secondly, I think an inverted hanger between the band and the joists makes sense to transfer the wall loads from above. Would you try to size the hanger to take the entirety of the wall loads, or some portion of them based on the width of the sill plate that is over the band, or something else?

 

[TRAK.Structural]

Are there existing dropped or flush beams across the bump outs that may be taking some load off?

Yea I had that same thought. So far it doesn't appear so. I've asked for some more ceiling to be opened in the adjacent areas just to be sure.

 

[KootK]

How many joists do you distribute the load from the walls to?

No specific number of joists unless I'm trying to spread out a concentrated load, similar to what @XR250 has described.

This, like many load distribution situations in structural engineering, is really more a matter of good practice than the specific attribution of loading.

There's really no such thing as a uniform load in the real world save, perhaps, fluid loads. As such, some amount of load sharing is almost always a good thing.

Theoretically, you could share to as many joists as the flexural capacity of the rim member allows for. That, however, also needs to be tempered with consideration for how much any one joist cantilever can deflect before that implies damage. So it gets complicated, which is usually the cost of redundancy.

TIA for the insight.

Thanks for being cool about the constructive criticism. Not everyone has that in them, me included. I prefer to fight until I'm burger and then hate myself later for being an inflexible egomaniac. This, I hear, is the path to mental health.