Basement XPS Foam with Fiberglass Batt Insulation Walls
Wytas
| Posted in General Questions on
I am finishing a basement in climate zone 5 (Massachusetts) and wondering about the choice of kraft faced or unfaced fiberglass insulation. I have read several articles and get conflicting information, but I am leaning more towards unfaced. Here is my wall assembly. Poured concrete foundation, 1″ XPS Ridgid Foam glued to foundation walls, 2×4 wood framing tight to XPS, (I would go unfaced insulation R-15), 1/2″ drywall with latex paint. Am I correct on going with unfaced? Or since the XPS is 1″ I could use kraft faced and not worry about moisture? Any input would be appreciated.
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Replies
The reason there's controversy is that neither will solve moisture problems in a basement. However, the 1" XPS will solve the problem. Once you have that, you needn't worry about faced on not. Faced might be a little better because it would slow down any moisture diffusion if you had the inside extra warm and humid in the short term.
But if you are interested in green building, XPS as currently produced by most manufactures has a huge climate impact because of the gas used to blow the bubbles in it which is 1430X worse than C02. You can subsitute EPS and get the same R-value for cheaper (but you'd need it a little thicker, or graphite-infused EPS to get the same R-value per inch, still cheaper than XPS, or you can see if you can talk to the special order department at Home Depot and get them to order the new "NGX" foam from Owens Corning that is XPS with a different blowing agent that isn't as bad. But that's more expensive than EPS or graphite-EPS.
Thank you for the information and respond as I am just learning about the different types of foams.
I have already installed the XPS to the foundation, and would rather install kraft faced (better fastening to studs). So the use of 2 vapor retarders (1" XPS & kraft faced) shouldn't create an issue with any moisture inside the wall cavity?
How would you stop the moisture coming through at the foundation wall using EPS? What would a basement wall assembly look like using EPS instead of XPS?