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Old 07-02-2009, 08:42 AM   #1
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Building knee wall in basement, best approach?

The foundation is about 3' up all around the fist level of our split level and I want to frame it out and drywall it but I've found that it's not even close to level and parts of the wall are higher than others etc. What's the best way to build this wall up so that it's level with the outside wall that exist? Can I shim it up so it's level?

This picture is my first attempt at create a well section. Just for this 4' section I had to use 8 shims and all parts of the wall were different heights. The wall is not attached yet I'm trying to figure out the best way to do that too. I'm going to put some foam board between the concrete and studs too.

I'm using 2x4's so I can put in outlets along the wall too.
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Old 07-02-2009, 09:00 AM   #2
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That looks exactly like my bi-level's "ground" floor.

I didn't do the work (although I had to get into the wall last year), but my lower section is pretty much framed out just as you have it. The builder framed out a lower wall, and shimmed it where needed (but he nailed the lower plate to the slab, no shimming there like you have). I have a double set of double-hung windows in two rooms on the front facade, and in place of a traditional window stool, he basically made a shelf made from 1x6 all the way along the wall as a cap for that framed out wall. I'm not saying it's the way to do it, but that's what I have.

I have to look at your pics again once I post this...

What's the deal with your window casing. Am I seeing it correctly? Was the mud sill notched out and the window frame attached directly to the foundation? Or is it installed directly to the top of the mud sill? I'm getting old, either that or I need new glasses.

Unfortunately I don't think you have as much room as I did. I just went and looked, and the lip of the vinyl window frame is about 3/4" higher than the shelf/stool. Your window is a bit lower. In my wall, he attached the shelf/stool directly to the top of what was left of the 2x6 mud sill after the original outer wall was framed, insulated, and rocked. At the window, he must have used a piece of 1x8 stock along that wall, because even though there's 4.5" of shelf along the rest of the wall, it fills in seamlessly up against the window frame (which is an inch and a half in from the sheet rock). Man, I wish my camera was working. But in your case, you've got some wood going on there that I can't tell if it's a double mud sill or just some stock nailed to the mud sill and existing framing.


Last edited by Aggie67; 07-02-2009 at 09:18 AM.
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Old 07-02-2009, 09:11 AM   #3
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I currently have the shims on the bottom but I'm afraid that might rot out and that kind of defeats the purpose of having pressure treated lumber on the bottom. I tried shimming the top but I'm afraid the drywall will break if someone puts pressure on it where there are no shims.
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Old 07-02-2009, 09:45 AM   #4
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You could shim the top between the top plate & each stud
Or cut a small PT piece to fit on the bottom as a shim

BUT, you shouldn't have to shim at all
As you go to the left each stud is cut slightly taller
No shimming
I had to do this on my sunroom as the old cement patio sloped 2"

Last edited by Scuba_Dave; 07-02-2009 at 11:45 AM.
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Old 07-02-2009, 10:34 AM   #5
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It is more of a hassle to do, but the best way to do it would be to cut each stud individually so you the pressure treated bottom plate rest wholly on the floor, and not on untreated shims. You can lay down the bottom plate, and then measure/insteall each stud on the end so you can then fasten your top plate level. Then, you can measure the size needed for each stud individually since the bottom and top plates will already be in place you'll be able to get really accurate measurements for each stud.
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Old 07-02-2009, 01:40 PM   #6
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Any untreated wood, as the end wall/corner stud, touching concrete wall will wick moisture and mold. This is why the stub wall should be 1" away from concrete wall.

I would rebuild the wall, either cut studs individually as mentioned or add a 2nd top plate. Never shim under a wall's bottom plate. Never shim between the stud and top plate. Any pressure on top later will cause nail pops in wallboard.

As this is below grade, I would glue 1" of foam board to concrete, then space wall for ventilation.The foam acts as a vapor barrier. You still need one on top wall, with the insulation if in cold climate zone.

Towards the end: Be safe, G
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Old 07-04-2009, 01:07 PM   #7
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i would agree with cutting the studs indavidually, shiming is just to unreliable your situation. my home was built in 1880 and have remodled the entire house interior and exterior, and to be honest with you i dont think i could work an a straight and square house, haha.


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