Quote Originally Posted by vastator View Post
Can anyone tell me if the R value of blown in cellulose is based on inches after it is blown in or after it has settled/compacted over time?

I am curious to know if it is true that as it settles, you would lose R value due to the thickness becoming smaller.
It seems the answers are ... yes , yes and yes. As with any insulation material that composed of a material made of fibers it relies on the " fluffy " nature to maintain it's insulation performance. So as it settles it will lose a portion of it's insulating properties and reducing it's R value.

In researching this I haven't been able to find a definitive number as to how much reduction of the R value is lost other than it is reduced somewhat.

Here is a link with some information : http://www.hgtvpro.com/hpro/bp_insul...243847,00.html