What is the best way to finish basement walls?
I'm putting in a 2 piece washroom in a finished basement. I've removed everything back to the foundation wall in that one area where I will be building. The basement was finished with tar paper on foundation wall, 2 by 2 framing with fiberglass insulation, vapour barrier and drywall. Everything I've researched including articles on this site suggest this is the wrong approach. I plan to glue 2" rigid to foundation wall, 2 by 4 framing with roxul and drywall. Is this best approach given the rest of basement is done the old school way (incorrectly)? Thanks in advance your site is new to me and is a great resource.
The wall you describe is not great, an interior vapour barrier is always a bad idea in basements. What condition was it in? That will give you an indication of what state the rest of your walls are in. The tar paper would be helping a bit by preventing some of the moisture from the foundation wall from migrating into the stud wall and insulation, so it’s a good thing that was there. With luck the rest of your walls may be in reasonable shape. The wall assembly you mention – putting rigid foam insulation against foundation walls followed by a stud wall and Roxul / Rockwool insulation and drywall is a good idea. You may have seen it but this page shows the best way to insulate basements
Building better basements: how to insulate your basement properly
If you look at some of the diagrams in that page you will notice a few things that you may want to include in your renovations, specifically raising the bottom plate up on foam blocks to prevent water damage in case of flooding, that will also stop moisture from the concrete (in case there is no vapour barrier below the concrete) from damaging the wood. This is also a good time to check and see if you have high radon gas levels in your basement and deal with it now, read here about How to remove radon gas from basements.
I used to really like using the pink sytrofoam with the grooves in it for the metal channel for basement walls. It ended up fitting flush with the foam. I used to fasten it with tapcons. I have been unable to find it lately, anyone know where it went and why? thanks george
The first thing I do is confirm there are no cracks in the foundation. If so get them repaired first. Look for any signs of water infiltration. Ensure the basement floor drains to either a floor drain or sump pit. After that is all completed, then I move onto finishing the interior.
The basements I have completed I have used the insulated drycore for the floor. Then 2" rigid against the foundation wall. Tape all joints. Then I use steel studs and Roxul within the stud spacing. The main reason I use the steel studs is for convenience, low noise ( no cutting of wood studs), and no dust. Do not apply a vapour barrier on the inside. The headers above the sill plate I use 4" of rigid and I make these about an inch smaller in both directions and fill the voids with expansion foam. This creates an airtight seal. Then build out the space above the metal framing with Roxul.
This provides a nice cosy basement.