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Community and Q&A

Insulation for a Finished Walk-Out Basement

sthfrk | Posted in Energy Efficiency and Durability on


I’m finishing my walk out basement in Zone 4 (Northern Virginia). The house was built in 2003, vinyl siding, house wrap and exterior sheathing. Part of basement is below ground, part above. On interior of the poured concrete foundation,  what are pros/cons of the following insulation options:
1. Foamular NGX F-250 (or another rigid insulation), then studs, then drywall
2. Foamular NGX F-250, then studs,  ROCKWOOL Safe’n’Sound  batt insulation  then drywall.
3. Mineral wool directly against concrete, studs, safe n’ sound, then drywall
4. Studs (not touching wall), Safe n’ Sound, then drywall.

Looking for products with least mfg and health impacts, and would like to diminish sound from room to room.  Thank you in advance.

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  1. user-2310254 | | #1

    If you haven't already, be sure to read this article:

    If it were my home, I would install R-10 of rigid foam (NGX or EPS) with a 2x4 stud wall for wiring and then drywall. EPS is probably cheaper than NGX, but I would go with whatever I could source. Rockwool against the poured foundation would be a none-starter since it is an air permeable insulation.

    1. sthfrk | | #2

      Thanks Steve. Would you see any benefit to mineral wool between studs?

  2. user-2310254 | | #3

    One of the experts may comment. If you are inclined to add insulation, high-density fiberglass is likely to be more cost-effective. Rockwool is expensive and seems to be hard to source at the moment.

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