I'm converting a carport into heated space and decided to install a subfloor to raise the room to the same level as the rest of the house. I have roughly 1"-3" of clearance below my floor joists, so it isn't a crawlspace. I'm not planning on making it a vented space, and I've read about different approaches to seal spaces like this for insulation purposes.
Here is a picture of the most difficult part of the insulation project before the rim joist is installed:
I'm trying to figure out which insulation solution is the best for my scenario:
- It's technically an 'unvented crawlspace'. Can I use air-sealed rigid foam insulation along the rim and above the bricks and be done with it?
- Should I use R19 kraft-backed batts all the way along?
- Should I use R30 kraft-backed batts all the way along?
- Combination of two of the above?
Note: I'm in US climate zone 3 and care more about cooling my house than heating it.
I've read about heat soaking through the floor. Would this be an issue with approach #1? Would the difference between R19 / R30 actually be noticeable?