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How to insulate a step down 8" foundation that has 6" framed walls?

bulwinkle's picture

How to insulate a step down 8" foundation that has 6" framed walls? (post #205660)

bulwinkle on Sun, 01/22/2012 - 12:00
in

My Homes foundation steps down  to allow a walk-in basement. The foundation wall is 2" thicker than the framed wall that sits on it. I would like to insulate and drywall the basement but I'm not sure the best way to do this.  I'm mainly  worried about moisture and the best way to apply the vapor barrier.   Any ideas would be great.

-A +A

bul (post #205660, reply #1 of 5)

by calvin in reply to bulwinkle [original] on Sun, 01/22/2012 - 12:24

I assume the thicker found. wall is to the inside.

I had the same situation and elected to frame the first floor (the living area floor that tucks into a hillside-with the steps going down the sides) using 2x10's.  Plenty of glass on the low side-very minimal number of pcs. of studs used, so the expense in framing not large-back wall studs are 15" long, only on the low are the studs semi full size-6'. 

I did this because I didn't want a ledge to the inside-though you certainly can utilize that design feature of a ledge.

As far as moisture-deal with the top of the foundation and the interior  to eliminate condensation, because you have probably taken care of the waterproofing on the exterior.

or am I way off base?

 

Got a picture?

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Correct. The ledge is on the (post #205660, reply #2 of 5)

by bulwinkle in reply to calvin [original] on Sun, 01/22/2012 - 12:41

Correct. The ledge is on the inside. The 2x6's are fiberglasss insulated. I'm not sure how to make the wall flush and not transfer the moisture from the concrete wall to the studs above. And how to properly provide a vapor barrier for both the wall that sits on the foundation but also the wall that will extend from the slab floor to the ceiling.

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............. (post #205660, reply #3 of 5)

by calvin in reply to bulwinkle [original] on Sun, 01/22/2012 - 12:47

I think is know the orientation of the wall.

I don't see any sill sealer on top of the foundation, between the treated sill and the concrete.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 

It is there. I just don't (post #205660, reply #4 of 5)

by bulwinkle in reply to calvin [original] on Sun, 01/22/2012 - 12:58

It is there. I just don't take a good picture.

I was thinking of gluing 2" foam over the studs then running the interior wall as you normally would, and I would shim if needed between the outer wall and the wall with the drywall. Should the vapor barrier go up flush against the foundation or against the drywall? 

Our basement (in southern MN) (post #205660, reply #5 of 5)

by DanH in reply to bulwinkle [original] on Sun, 01/22/2012 - 13:33

Our basement (in southern MN) is this way.  The way we got it from the builder is with a ledge -- conventional framed/ FG insulated wall above, 3/4" foam between wood lath below, over the block foundation wall.  Top is rocked, the bottom covered with paneling, solid wood ledge.

This works pretty well, though of course if we were doing it over we'd at least thicken the foam to 1.5" or so.  If the foundation is properly sealed and tiled then you shouldn't need to worry about moisture, and, with the foam, no vapor barrier should be needed below.  I'd have no concerns about replacing our paneling with rock, save for the fact that our foundation is NOT sealed or tiled, and so we get a little moisture in at the corners every few years when it rains for a solid week. 

All we've done is to replace some of the cheap paneling and pine ledge with nicer stuff, and I redid the foam behind (making it tighter) and foamed gaps below the plate (built before sill seal was the norm) while the paneling and ledge were off.

If you want a straight wall, you could shim out the top to the plane of the bottom.  It would be a little tricky preventing a bulge/dip at the junction, though, and you'd have to build tunnels for the windows.


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