Liquid air barrier for basements?
I live in Maryland and would like to improve the thermal performance of my basement. It has about 6 feet below grade and 3 feet above grade with slider windows. I currently have wood paneling in front of the brick masonry walls with one inch separation. Since the paneling includes a partition wall and looks nice, I would like to keep it. But I am thinking of shifting it forwards to allow for insulation between it and the brick wall. However, I doubt the paneling is effective as an air barrier. So my questions are: does a basement need an air barrier (I imagine yes for at least the above grade portion?)? Can one apply a liquid air barrier as they do externally? I see some advertised that are vapor permeable, but are they ever used inside basements? I would like to consider alternatives to spray foam. The basement has been dry for many years. Thank you in advance.
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I guess people this question is as odd as I thought it was. I guess my question is then whether rock wool is considered an air barrier. This site lists rock wool as the non-foam approved insulation for basements (and not fiberglass or cellulose). But I haven't seen that rock wool is considered an air barrier. Is it?
Alternatively, there are sections of my basement where space is very limited, and I wondering if a judicious use of loose fill aerogel (R-10 for one inch) by Cabot might fit in some tight spaces; but when I asked the company they were not sure it was an air barrier (but unaffected by water and vapor permeable). Could I use aerogel with a liquid air barrier theoretically?
What's the foundation construction. You mention bricks. Is that a 3-whythe structural brick foundation wall? Is there any sub-grade water-proofing? Perimeter Drain?
If you've had no water leaking in for many years, then it's likely a tightly-built wall and would be an adequate air barrier assembly, except at the sills & rim joists, which you should seal with a can of spray foam.
No fibrous insulation is an air barrier, but well-nailed paneling is close enough as long as penetrations (e.g. electrical outlets) are sealed. Aerogel is outrageously expensive for what it offers. If you have limited space, I would advise rigid XPS foam board with taped seams. Where you have space, use mineral fiber batts.
What you don't want in a living space is any kind of spray-on chemical which, at least during curing, will outgas a variety of toxic compounds.