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Insulating Walk-out basement

Posted by wingsred (My Page) on
Wed, Feb 28, 07 at 16:29


If at all possible, I'd like some assistance on how to insulate a walkout basement with foundation walls 50% above grade.

I've read through the Building Science recommendation of rigid foam being adhered to the foundation wall and if additional insulation is needed, adding unfaced butt insulation between the framing. However, I'm in unclear as to what the appropriate method is for walk-out basements since 50% of the foundation is above ground, which allows moisture to dry outward (above grade portion of foundation) as opposed to mostly inward (below grade).

Are there any suggestions or other references that anybody can point me toward?


Follow-Up Postings:

RE: Insulating Walk-out basement

We didnt add insulation directly to the cement foundation, but just to the framed areas. Our basement is fine here in Georgia. We have a walk out basement.

RE: Insulating Walk-out basement

I'm curious on this as well. We're in the framing stage of our new home with walkout basement. The uphill wall is 90% below grade, the side walls are 70% below grade, and, the rear wall is typical wood frame.

I've read the same comments on moisture lock, but am unclear if this is specifically for a submerged basement or does it apply to walkouts as well?

RE: Insulating Walk-out basement

To add complexity to this issue, I reviewed my basement walls last night and they are far from a smooth, flat surface(poured concrete). Without some type of sanding I don't think it would be possible to properly attach foam board to the walls without gaps due to the uneven nature of the walls.

RE: Insulating Walk-out basement


RE: Insulating Walk-out basement

I used a grinder to smooth the foundation walls for rigid foam adhesion. 2x4 walls with unfaced batts were used behind the foam. I had Icynene sprayed around the entire rim joist perimeter area. I caulked and spray foamed all seams and penetrations in the basement. So far, I still have the fiberglass batt insulation in the rear framed wall that's above grade. I'm weighing the cost of other more air tight insulation options for that wall.

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