[GBlist] Re: SB: Venting cathedral ceiling/roof insulated with cellulose?

["Robert W. Tom" <ArchiLogic@yahoo.ca>]

5/14/02 12:22:11 PM, Whitney Burgess & Tristan Kelley <raven@tetontel.com> 
wrote:
[snipped & pasted]

>...whether or not to vent the cathedral ceiling/roof ...that will
>be insulated with dense-packed cellulose.  

Whitney & Tristan;

Theoretically, you should not need to vent the ceiling/roof if the interior air 
barrier at the ceiling is perfectly air-tight. 

In reality, $#!+ happens and theory (as well as the air barrier) is, more often 
than not, imperfect.

In addition to the likelihood of an imperfect air barrier, the reality of "$#!+ 
happens" also means that moisture will likely find other ways to get where it's 
not intended to go.

Without a ventilation airspace to permit moisture to cook off in the event that 
it does find its way into the ceiling insulation, damage is almost certain to 
occur.

In providing a ventilation airspace to accommodate drying, you lose a bit of 
space that otherwise could have gone towards insulation. That lost R-value is 
pretty easy to regain elsewhere.

--- * ---
Rob Tom
Kanata, Ontario, Canada
(remove the "chaff" from my edress if you hit "reply")

Please visit http://www.theHungerSite.com daily



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