Interior Basement Wall Advice
Hello all! Long time reader, first time poster.
I need some advice for insulating a full basement. Here’s my situation and conditions as they currently exist. Hopefully I’m not forgetting anything.
-Location is right on the border of climate zones 4&5.
-Bare concrete block walls.
-The entire basement is below grade
-R-19 fiberglass insulation between the basement and first floor with kraft faced vapor barrier on the basement side.
-On some sections of the exterior wall, the sill plate is flush with the inside top of the wall.
-On the back wall, which is about 65′ long, they must have used a thicker block around 10″. They used a 2×6 sill plate, so there’s a gap of 4″ or so from the edge of the sill plate to the inside of the wall. So…you can look down into the block wall cavities from above.
There used to be some drainage problems where water would enter the basement, but those have been fixed. The current temperature and humidity readings are 54 degrees and 67%, respectively.
There is condensation against the rim joist where there are pieces of fiberglass insulation shoved directly against them.
Here is my tentative plan:
1. Remove fiberglass from rim joists and allow to dry.
2. Install rigid foam on perimeter walls
3. Cut small strips of 1/2 rigid foam to lay flat on top of wall section to cover it up.
4. Spray 3″ of closed cell spray foam against rim joist, and spray continuously on sill plate and the top of the wall to the top of the wall boards to create a continous layer of insulation.
5. Tape the seams of the rigid foam wall areas.
How does this plan sound? Id like to use 2″ of rigid foam on the walls. I was initially going to use Dow Thermax so that I could do the installation for now without a thermal barrier, but I can’t see to source it anywhere.
Ive called a lot of suppliers, but it seems like the best prices are still Home Depot or Lowes.
Here are my options:
Dow Super Tuff R (R13)
Pactiv GreenGuard (R10)
RMax Thermasheath (R13)
I know two are Polyiso with facers, whereas the GreenGuard is XPS.
I guess ultimately my two questions are: Is my plan sound? And which foam should I be using?
Thank in advance for any advice!
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