What is the best way to Insulate a basement and floor joists that are embedded into the concrete?
Hi, I have recently purchased a home in Toronto. We had some water issues and I've opened up the walls where I found some mould to see that the previous owners installed batt insulation directly onto the concrete wall and didnt have a vapour barrier. I've also noticed my joists are embeded into the wall. How would I properly insulate my basement wall and the embeded floor joists? Right now the home has roxul insulation in the ceiling space as sound proofing and the roxul/batt insulation is in the ceiling space right up against the exterior wall.
Installing batts of insulation directly against a basement concrete wall is a disaster for sure. That was unfortunately a common building practice in the past and a lot of homeowners are having an unfortunately similar discovery. Do you mean that there was no vapour barrier afterwards/ that would actually be a bit better. There was usually a poly vapour barrier installed after the insulation and stud wall seemingly to ensure it would go moldy as quickly as possible. Either way, if you are getting mold and you have a stud wall with batt insulation against concrete then I don’t see a whole lot of alternatives beyond removing it and redoing it. here is a page that will help –
How to renovate basements so they don’t go moldy
Apart from that, the other issue you point out is having floor joists embedded in the concrete. That’s another issue where you need to be careful. Concrete is porous so as it is likely not protected from exterior moisture, it will stay wet. What we usually recommend at this point is to leave them exposed. If you cover them with a vapor barrier, or even spray foam, that will prevent them from drying and it may lead to rotting, that’s a whole other can of worms you really don’t want to open.
Hey David, do the wooden joists come through to the other side of the concrete, or are they embedded in pockets?