lastlight's 404

[MitchM]

No vapour barrier behind the studs?

[chris121277]

Originally Posted by MitchM

No vapour barrier behind the studs?

I'm pretty sure vapor barrier always goes to the warm side on the insulation

[Skimmerking]

Originally Posted by MitchM

No vapour barrier behind the studs?

Vapor barrier goes after the studs

[MitchM]

Insulating basements is tricky because the concrete wall is a source of moisture as well.
The lower part of the foundation wall that is in contact with outside soil will always be a source of moisture unless the foundation has been waterproofed. The upper exposed part of the same foundation wall will be a place where the moisture can escape.
Vapour barrier should be on both sides of the insulation for basement walls, with an area at the top of the foundation-side vapour barrier left so the insulation is only exposed to the "drier" portion of the foundation wall.

[lastlight]

Our previous 2 houses were brand new and of course the outer walls were already insulated when I did development. When I did the electrical at each place I don't recall pulling back the insulation and seeing poly between the studs and the cement. What's the general consensus guys? I suppose I can fish some in back there but this is news to me?

[MitchM]

The best scenario is to have the exterior of the foundation wall insulated.
Since this isn't new construction, the second best practice would be to have rigid foam against the wall then the stud frame wall.

Here is a paper that explains it a bit better.
Of course, what you do is up to you.

[MitchM]

If your previous houses were in Alberta, the building code doesn't really deal with that issue, so it's pretty much left up to the builder what they do.
What we used to do is hang a layer of poly down from below the floor joists and slice some openings in the vapour barrier, above the outside grade.
That way, the insulation spaces could still breathe and would be exposed to the "drier" portion of the foundation wall.
It wasn't perfect, but it was better than leaving the insulation and studs fully exposed to the "wet" portion of the foundation wall.

[lastlight]

Actually I'm forgetting to share all my plans I guess. I don't even plan to insulate the walls I've built so far. The fish room and the coridor behind the tank will just be drywalled. I want this sealed area to be like a cold-room for some free tank cooling. I should also note that the fishroom wall is a shared wall with the condo next to us. The coridor behind the tank is however exterior wall. I plan to insulate that exterior wall once it extends past the end of the tank as that will be my office. I will most likely do the poly with slits like you have recommended. Thanks!

[lastlight]

Had a helper down in the basement today. Turns out the stand for my auto-topoff and mixing tank needed a bit of TLC.



Stand is done with my 2x6s for lateral stability, 3 coats of KILZ Premium and foam.