What is the best way to insulate my basement?

Chris Rogers
Updated: Aug. 7, 2020

I have an unfinished walkout basement with 3 sides at or below grade. The two sides of the house have poured concrete step foundation down toward the rear with framed walls on top. The framed areas have fiberglass insulation but the concrete is bare. 

I want to finish these walls with a newly framed wall covering the concrete and partial wall. Should I:

1. Install Foam Board Insulation over the bare concrete and leave the framed walls insulated as the are?

2. Install Foam Boards over the concrete and replace the foam in between the studs and maybe even put the existing fiberglass batt insulation back in the cavities over the foam?

3. Leave it as is and insulate the new wall that will be framed in front of existing wall and foundation?

I know I don’t have to cover up concrete it is just preference. I’d rather not see concrete and then have it broken up with drywall “steps”.

I live in Kentucky if this helps.



Responses (3)

Paul Hylan
Paul Hylan 2 years ago

Hey I framed my whole basement, can I just put foam board in between each stud? 

Mike Reynolds 2 years ago

Rigid insulation is best right up against the concrete wall rather than between studs, but it sounds like your past being able to do that. As an insulation material you can put it between the studs but at this point you may as well use batts as it will be much easier because they are cut to size. With foam you'd need to cut each piece to size, so it's going to be a lot of labor and it will probably still leave gaps. If you're doing that looking for the vapor protection of the foam then I'd suggest trying to slip a poly vapor barrier behind the studs to prevent moisture from the concrete from wetting the studs. Does that make sense? The  concrete is where the moisture is, so separating it from the stud wall witha waterproof layer is what you're after. Whatever you do just don't staple a vapor barrier to the interior surface of the studs. That's probably where you will see everyother vapor barrier installed, but it's still wrong.