# What is this second layer behind drywall?



## acerunner (Dec 16, 2009)

So I was doing some ceiling demo and discovered there is more than just drywall hung in the ceiling. Behind the 1/2" drywall is another layer of 1/2" board. It looks like cork or compressed paper fibers.

Anyone have any idea what that is or what its for? My best guess was extra sound dampening.

It also made it very hard to cut out because the paper fibers kept clogging the saw blade.


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## Willie T (Jan 29, 2009)

Looks like Homasote, maybe their 440 SoundBarrier. Yeah, I think it's made from compressed paper.


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## epson (Jul 28, 2010)

It looks like Homasote which was a product widely used in the 1940’s all the way up to the 1970’s, then when drywall started being used homasote became a thing of the past like everything else.


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## acerunner (Dec 16, 2009)

so what's the best way to cut through it?


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## Willie T (Jan 29, 2009)

acerunner said:


> so what's the best way to cut through it?


A razor knife.


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## bjbatlanta (Jul 16, 2008)

Or a drywall "keyhole" saw.


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