My wife and I were looking at replacing the carpet in our living room with a locking wood floor for dance practice. It's on the first floor, on a slab. However, we pulled up a corner of the carpet and there is a straight gap/crack running the length of the room on the outer wall, with a ledge that's higher than the rest of the floor. The ledge is about 5 inches wide and the height varies from about 1/4 inch to 1/2 inch above the rest of the floor, at least in the uncovered corner. Is this part of the foundation or what? Can we even have a wood floor installed over that? The tack strips are still in place, and the ledge is just inside of them. That's masking tape that was used to hold down the padding. There's a pretty good sized gouge in the lower right, too. Not sure what the rest of the edges look like, but the floor at upper left (front of house) looks like it runs flush up to the wall.

the slab is cracked?....

it wold be a peculiar settlement if that were the case...

and you say foundation, why would there be a slab then?..the slab would be to the inside of that.....
.but one thing is obvious...

you cn install into that and have a seamless result..

something will have to be done to that area..whether taken down.. or leveled up to it..
or some trick trimming riggin it..

you might just wanna add a layer of 3/4 plywood to the slab..this should bring you up to the deviation.

then you can use some leveler to even out from there..

Looks like the ole crappy stem wall constuction and the slab portion settled or it was never even Steven to begin with. Been there done that and the carpet too. Needs some serious work by someone who knows how to handle that situation.

Pull the base, grind and and or use exterior self leveling compound

Thanks for the replies. So you are saying to pull the baseboards, then grind down the top of the stem wall that's sticking out into the room to the level of the slab? Am I going to hit any rebar doing that, or otherwise compromise the integrity of the wall? Is it common for the stem wall to extend into the room so far?

I understand the plywood concept, though I wonder how solid that would be under the wood flooring, unless it's anchored somehow into the slab.

You can grind the concrete and stem wall plus patch the floor. Also look up floating plywood subfloor, very solid.

Some grinding is definitely in order to level out this problem. And over slabs, I very much like the idea of a floating sub floor.Slabs generally cause heavy moisture transmission into the sub floor / flooring and if you have room to do a floating sub floor, you'll have the opportunity to lay down some 6 mil plastic under it which will effectively keep moisture from coming up into your flooring.