How to insulate wall, 1/2 foundation 1/2 framed.

Hello all,

I've tried searching here, there and everywhere, and I keep finding conflicting information, so I figured I'd throw my specific situation out there and see what you have to say on the subject.

I have a basement in need of updating. I've torn into the first room to repair a few foundation cracks, and now I have the dilemma of how best to frame and more importantly insulate the space.

The entire lower floor of the house is bi-level, by which I mean the lower ~3-4ft of each room is below grade with concrete foundation, above which point it is wood framing for the remaining height. The first room I've started on had no insulation at all in the concrete lower section, and was framed up 2x4 on flats. There is insulation in the upper framed portion built on top of the foundation, but presently no vapour barrier.

What is the best way to approach tieing this all together? I'm likely pulling down all the drywall at this point anyways, so if the best approach involves a barrier, I can put it top to bottom.

I should also note, the wall will not be straight vertical. The foundation wall is the narrowest portion, and the framing on top if it pushes out. Prior to tearing it open, there was a 5" ledge all the way around the room, actually all of the exterior walls in the lower level.

Anyways... Do I rigid insulate and then 1x3 fur out and drywall, or rigid and then frame 2x4 proper and batting, or do I skip rigid and just offset the 2x4 with a gap to the foundation, or.... And then, the next question would be, do I attempt to vapour barrier the entire wall, and if so, which way? Everything I've taken in so far says to vapour barrier at the inside, so, right below the drywall layer. But then I've also read that rigid acts as a vapour barrier, so that would mean somehow transitioning from a external (foundation) barrier (rigid foam) to an internal barrier on the upper half.

Hoping some of you have some insight to offer. Every time I think I have a plan, I find a new piece of information or new opinion and start second-guessing everything.

Welcome to the site.
Ist the questions, You fixed cracks , was that to stop leaks, do you expect to stop leaks by patching inside? the quick answer to that is not very often.

Foam can be used if the concrete is flat and straight enough.
We build a 2x4 wall with a space to the concrete so wood does not touch concrete, with a half wall we place a 2x8 (or what is needed to allow a 2x4 wall about an inch way from the concrete) on the flat against the studs in the upper wall about 5" above the concrete, bottom plate on the floor with a vapour barrier between it and the floor and stud it in.
Batt insulation and vapour barrier then drywall.

Yes, the cracks were epoxy injected yesterday. Prior to doing this, I had them looked at by 4 different contractors, all of whom also performed excavation and external repair/patching services, but all 4 advised the cracks were ideal candidates for injection repair from the inside.

So if I'm understanding correctly, you generally start the bottom (foundation) wall set off by the equivalent of a 2xX on flat, glue the moisture barrier to the concrete floor, and attach the bottom plate over the glued barrier? And then stud up high enough to reach across to the framing on foundation, tie into that, then batt insulate the whole thing from top to bottom and then run the vapour barrier up the outside?

Most of our builders now tend to have the wall, all the way up and do away with the ledge.
And yes you almost have it. We start with the 2x6 or 2x8 against the framed wall a few inches above the concrete to allow insulation to all the way up and over the top of the concrete. Figure how high you want it and then mark that at one end of the wall and measure from the ceiling down to mark the other end of the wall. Snap a chaulk line so your first 2x? is level. Onece you have that 2x? in place, level down to the floor and mark that at both end and snap a line there. pick up a roll of sill gasket ( thin white foam material 3 1/2 " wide ) for between the floor and the bottom plate. Measure each stud as the floor is seldom level. Actually nothing is straight and level, that is why we measure down from the ceiling and then level down from the top, and you have a better chance of keeping things square and straight. Yes we are assuming that the framed wall is straight and square and the ceiling is level.

I agree do away with the ledge and straighten up the wall. Extend windows in and seal and insulate per Neal.

I was actually considering that too, but have been having second thoughts on account of losing a few inches of floor space on the exterior walls, but more than that, the fact that the window wells (probably not the right term) will end up being a 10-12" deep window if I go that route. I'm not sure what feels worse, a 70's style ledge all the way through the basement outer walls, or abnormally deep window mounting.

While I have your attention, I might as well ask; with a garage (not currently parking in it, but who knows later on) would you still vapour barrier (poly) the side closest to the actual indoor space? Ie, poly right around the joists and subfloor on the roof, and then batt, and then drywall...

If you frame to the ceiling add the same 2x? to the top for the top plate, still up against to framed wall, that gives you the required firestop at the top so a fire in the wall dosn't spread to the floor upstairs quickly.

Ya that leave the will frame about 12 to 13 inches deep but the trick is if you have a 3 ft wide window, frame the new wall opening a little wider like 4 ft, then it will look just like a 6 inch box out that we hate putting in for kitchen windows
We just built a house with 5 of them, not sure why.