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Insulating basement - how to deal with waste pipes?

hurnik's picture

I'll try to attach the pictures of the basement, but basically there's the big 3 (or 4)" waste pipe that goes around 2 of the walls to the sewer (house was on septic and converted to sewer before I bought it).

What I'd like to do is use rigid foamboard against the cinder blocks and then stud/frame on top of that.

The issue is how do I insulate around the waste pipes?

There is a fresh air inlet as well that gets VERY VERY cold in the winter (to the point that I've seen condensation around it on the inside as the basement is obviously warmer/moister than the outside. Especially when it's like -20 with the windchill and the wind is blowing right into the inlet.

I hope I'm making sense of this (hopefully the pictures maybe help?)

I was debating about this:

On the two walls where the waste pipes run, just use rigid foamboard as best I could up to the pipes (and below them) against the cinder block.  Then either use 2x6 with a small cutout/notch/whatever in those spots so that I could get the framing up "against" the 1" rigid foamboard and then use Roxul or something for the stud bays.


use 2x4 and just kinda "butt" up against the PVC pipes but leave like 1/4" gap for expansion/contraction, but then I end up with like a dead space between the studs/roxul and the foamboard and not sur what implications that would have.

You can see that there was some water on the lower cinder blocks (the white stuff), but the original owners never had gutters.  I've installed gutters years ago when I bought the house and haven't had any problems since (17 years?).  Amazing what moving water several feet away from the house will do.

Soil is 100% pure sand (other than 1-2" of topsoil in the yard), BTW.

Thanks for any advice, please be gentle.  :)