I’m pricing out insulation for my renovation and it is about the same for 1 inch rigid foam exterior with R15 batt insulation in the stud bays and R20 closed cell without the rigid exterior foam.
I can decide which is better. I’m leaning towards the rigid plus batt but would like to hear some thoughts.
Framing the floor inside a crawlspace foundation keeps a gable-end addition close to grade.
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Replies
Checkout the Green Building Forum. They'll have an opinion on this.
It all depends on how carefully each choice is installed. There is a lot more detail to address using the batts with exterior foam as far as getting good air sealing. A good layer of spray foam is likely to seal better with an experienced installer. But there are different environmental costs to each choice .
The Green Building Forum is worth looking at for more details, but the choice really depends on you.
There's a bit of science that goes into knowing how thick the exterior foam has to be to prevent moisture from collecting in the sheathing. 1 in. may or may not be enough. To answer your question, we need to know what climate zone you're in.
I decided on spray foam more due to the confidence I have in my GC on installing spray foam vs rigid exterior insulation..
Foam between studs is almost a waste. Exterior foam works much better. What climate zone are youbin?
I'm on the border of zone 4 and 5. I decided on spray foam more because of my confidence in the GC to correctly install the rigid exterior foam correctly. I know I would end up with a better result with the exterior insulation as long as it was fine right but I was too worried about water and moisture issues.