[Greenbuilding] insulation

[Corwyn]

On Sep 25, 2007, at 11:02, Curt Sommer wrote:

> Winter is on the way...
>
> I'm adding some cotton loose-fill and cellulose insulation (that I got
> off craigslist) to my attic floor.  Is it ok for the insulation to make
> contact with the roof and the joists?

I have heard of some concern about putting insulation in contact with 
nail-less fasteners.  You might want to check that out, if you have 
them.

> I only have 7" right now but when
> I add another 6-8" it will make contact unless I pack it down.  I
> presume the vapor barrier on the roof would prevent any condensation 
> but
> I just want to make sure.  Yes, the attic vents are protected by 
> plywood
> sheets so there is no risk of being covered up by insulation.

The soffit vents need to have a clear air path, against the the roof 
surface, all the way to the ridge.  I am unable to figure out from your 
description whether this is the case for you.  Once that is 
accomplished, you could (theoretically) fill the rest of the space with 
insulation.  Keep the insulation away from heat generating things 
(chimney, recessed lights, etc.), of course.

A vapor barrier on the roof will do nothing (or very little) to prevent 
condensation inside the attic.  Most of the moisture in the attic will 
be coming from inside the house (yes, you want to reduce that as much 
as possible by sealing the attic floor before you insulate).  The rest 
of the moisture will come in via the vents, which can cause 
condensation under some circumstances.

Thank You Kindly,

Corwyn


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Corwyn
Kermit didn't know the half of it...
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corwyn at greenfret.com