Foundation surprise - repair options?

[Kenoryn]

So I was planning to put a deck on the back of my house, replacing some old 2x4 decks that have seen better days. The decks wrapped around an addition on the back of the house which is also need of some repairs - but turns out more than we thought. Once we got rid of the old deck we were able to pull the siding off the bottom of the wall (someone had put vinyl siding down to the ground) and check out the foundation. Not good news... see pictures.



As hopefully you can see, there is a small 5-6" thick poured concrete stem wall, but then they built a lousy 2x4 frame on top of it to hold up the floor of the back room. When that crapped out it looks like they stacked up a bunch of bricks under a few places, and that's what's holding it all up now!  This room is just an unfinished storage room right now, but we were hoping to fix it up and use it as living space eventually. The floor and framing of this room are in decent condition, but it will need a new roof soon, and when we do that we would extend the overhangs and put eavestrough on (I'm sure the lack of eavestrough hasn't helped the foundation situation at all).  Meanwhile I can't put the deck on until something is done with this. Now I don't know how to proceed - is there any way to fix this or build on that concrete stem wall for a proper foundation?

Any thoughts would be appreciated!

[Greg]

Jack up the floor inside the foundation/ponywall and support the floor, then rebuild the ponywall using treated lumber and proper fasteners.  There's nothing wrong with a wooden wall used that way, just the materials and/or repair done previously.  You'll want to create piers to support the deck independent of the house, the connection of the deck to the house probably caused the rot.

[Kenoryn]

Actually the deck wasn't attached to the house before. I think just age, the short overhang and a lack of eavestrough caused the rot. You can really see the gradient in the condition of the siding down the wall, from fine at the overhang to what you see in the pics above the foundation.

I was thinking of maybe pouring new concrete on top of the stem wall to flatten it and raise it up a bit more - it's not far above grade right now. Then maybe a wood frame could go on top of that. Alternatively I also have a lot of cinder blocks available I could use, but they would be wider than the stem wall currently is.

Still have to decipher what the building code says about any of this.

[Jack]

Still have to decipher what the building code says about any of this.

Be prepared for the possibility that the entire addition was unpermitted and the jurisdiction might make you tear it down (or if they're not feeling punitive, at least bring it up to current code).

Also, you checked to see if they require a permit for the replacement deck, right? The old one may have been freestanding instead of attached to the house for a reason (i.e., in order to avoid triggering the requirement for a permit).

[Kenoryn]

Yeah, I'm making the new deck freestanding so I won't have to get a permit for it. Already checked on that. ;) Also I just don't see the advantage of attaching a deck to your house.

From my previous discussions with them about something else, the building department doesn't have any records for my house. That might not mean it was unpermitted, though, just that they don't have records that old - the house is 124 years and the addition is probably 60 years old. I think it would be grandfathered at this point, beyond the statute of limitations anyway, but it's possible that when doing repairs you would have to bring it up to code, whether previously permitted or not, since certain types of repairs count as new construction (i.e. when I replaced my kitchen cabinets I had to bring the wiring up to code, apparently, because it was considered a new kitchen.)

First of all I'm worrying about getting a plan for a structurally sound foundation under there. I think I'll go with bringing the stem wall up a little higher, and that will allow me to slope the ground beside the house away from it for better drainage, too, then reconstruct the wall with PT lumber as Greg said. Building code seems to think 6" is wide enough for the stem wall as long as it doesn't extend more than 80cm above ground (if I'm reading this right). Thanks for your thoughts. :)