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no insulation vs. plastic insulation?

Posted by phoenix_nj (My Page) on
Tue, Oct 14, 08 at 10:36

I'm going to put 2" XPS on my perimeter walls. I was going to frame and sheetrock without any additional insulation between the studs.

Are there any sound issues with not filling the studs with insulation at the perimeter wall (ie, cinder block foundation walls)? We're just using the basement for the children's playroom. Maybe later, we might convert a portion of it into a media room.

Someone told me about plastic insulation that has no paper backing and therefore won't itself provide a food source for mold. Any comments/insight on this type of insulation?

Follow-Up Postings:

RE: no insulation vs. plastic insulation?

sound issues
Like noise?

plastic insulation
Sometimes XPS and EPS are referred to as "plastic." There is also recycled polyethylene terephthalate (PET) fibre insulation. I haven't seen it, but have read that it is difficult to cut and handle.

RE: no insulation vs. plastic insulation?

By not filling the walls along the perimeter foundation with insulation, will there be any echoing?

Yes, I was referring to the PET fibre insulation.


RE: no insulation vs. plastic insulation?


No more so than in any conventionally constructed room. However, if you're sound blocking the basement, you should also do something within the perimeter walls. If you're in far north New Jersey, which is in the cold zone, it will make economic sense to increase the R factor with some batts. If not, don't bother.

US Department of Energy Hygro-thermal Regions

Have you found a source for PET batts?

Here is a link that might be useful: Designs That Work by Hygro-thermal regions

RE: no insulation vs. plastic insulation?

But wouldn't leaving the framed voids empty create a space for cold air to condense on the relatively warm sheetrock?

I thought elimination of air-spaces was desirable.

RE: no insulation vs. plastic insulation?

The air between the drywall and the XPS should be warm enough that there is no condensation. But fiber glass is relatively cheap and I did fill in the space on my own home with batts.

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