Plastered Walls Insulation Help

Sep 28, 2006 2 Replies

I have removed the plaster and lathe on an exterior wall to discover that they backplastered as well. The cavity is only 1-1/2" thick in some areas. Can I fiberglass type insulation to this area? I have insulation that is for a 3-1/2" wall...can I use this without a problem?



compreessing the insulation cuts its r value.....

you can split the insulation by pulling it apart.

not certabout back plaster i would open the wall and install full insulation or look into foam in place for higher r value

For a given amount of insulation, compressing it reduces its R-value. But for a given amount of space, filling it with compressed insulation gives a higher R-value.

So to the OP, go ahead and compress your fiberglass insulation. You might get R-4/inch, instead of R-3.5/inch, but that's still only R-6 for a 1.5" cavity. You might consider a better insulation than fiberglass.

Cheers, Wayne

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