insulation on stairway and a vapor barrier question

codnuggetsNovember 27, 2009

I've read a pile of posts about insulating. 2 questions here I still need help with:

Firstly, I spoke with the permit office about basement insulation requirements, and the city code requires a 2x4 wall set 1 inch minimum off the poured concrete walls with r-13 and a vapor barrier. I'm going to go back and discuss options, but if I'm stuck with these requirements, should I still put up a layer of XPS if code allows it? If so how thick? Any issues with XPS plus a vapor barrier?

Secondly, the stairs leading down to the basement start from the kitchen, turn at a landing halfway down with a door leading to the driveway, and continue to the basement along the exterior concrete wall. What's the standard procedure for insulating this portion of the wall? Building a finished, insulated wall will reduce my stair width by 6 inches so I'm hoping that's not the case. I'll talk to the permit office about this, but I thought I would get some opinions in the meantime.

Thanks for any help.


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Put 1" extruded polystyrene (XPS) on the foundation wall, then finish the rest as they require. The polyvinyl vapour barrier is pointless, but it won't damage anything, according to Building Science Corp. I've had to do the same nonsense on two new homes. The most economical thing to do along the stairs is to use 1/2" or 1" XPS, followed by drywall above the staircase. It shouldn't hang over the stringer. Underneath, you can go thicker, as it doesn't interfere with anything.

Here is a link that might be useful: Basements

    Bookmark   November 28, 2009 at 12:03AM
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