What is the best way to do a basement renovation?
I finished a basement for a contractor and what we did was put tar paper on the concrete walls the left about 3/4 to an inch of air space than a 2x4 wall I think 16 on centre and used pink fibreglass insulation with vapour barrier break under the bottom plate and over the insulation on the interior warm side and then drywall over top, the vapour didn't end up being taped but maybe was acousticall sealant by the insulation company while they put that part up. what I'm asking is this ok because by all that I have read now that that isn't a good combo in a basement and wasn't sure if the tar paper even really did anything or its an old practice the contractor was used to doing?
Basements are often moldy, and unfortunately even after basement renovations are completed because people usually rebuild them in the same way, which would meet Einstein’s definition of insanity – doing the same thing over and over and expecting a different result.
The tar paper actually will help, that will provide a moisture resistant surface to separate your studs and insulation from the concrete, and that will allow moisture that accumulates to run down the wall and not be absorbed in to the stud wall. In a perfect world there would be a way to manage any water that drains down the wall, but that’s a good start. Did you see the following page about best practices for basement renovations?
Why are Basements Moldy? How to Fix & Prevent Mold in Homes
As for vapor barriers on basement walls, as you would read in the page above, that’s always a bad idea. The ground is wet, concrete is wet and porous, so sandwiching organic materials against it with a sheet of plastic will have one inevitable result, it will rot. The intention of vapor barriers was originally to prevent moisture accumulation and damage in walls, which it does above grade, but below grade a vapor barrier CAUSES moisture accumulation and rot. It’s a bit late now I guess, but what you should probably do if you can is see about cutting holes in the vapor barrier to let the moisture escape into the basement where it can be easily managed by a dehumidifer. Have you done all the mud and taping yet? If not slice it open wherever you can to let the moisture evaporate into the air instead of trapping it with your wood and insulation.