[Greenbuilding] detailed (older) article on double-wall .77 ach50 house

[JOHN SALMEN]

Good question - nice link. I'm still curious about roof assemblies. CMHC
here did a practical study a number of years ago on vented unvented roof
assemblies and the determining factor for condensation was air leakage from
the interior. I'm basically detailing unvented roofs with pretty stringent
air barriers but using materials that will allow drying to the interior -
pretty similar to exterior walls.

I don't like the exterior wall material in this house. I have sheathing
(standard ext. Ply) taped at all seams  with vb tape but also use a wrap - I
think a little redundancy is a good idea. I like the 2x4 frame as that is
what I typically use and if laid out properly can save a few trees. This
place seems to use a lot of lumber though and probably more than he
intended. A prefab truss manufacture for both walls and roof might have
worked better with less lumber - but then builders in NA are generally
framers.

John


-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Kat
Sent: July-01-11 3:17 PM
To: Greenbuilding
Subject: [Greenbuilding] detailed (older) article on double-wall .77 ach50
house

 From the most recent "Musings of an Energy Nerd" blog on the GBA 
website: a link to a very detailed article from June 2009 on the 
construction of a particular house in Maine that I hadn't seen before.

http://www.kaplanthompson.com/_images/publications/09.06-jlc.pdf

I wonder how their roof/ceiling assembly is holding up.  Does it allow 
for enough drying potential?  Might they get condensation on the 
underside of the roof sheathing (or is that physically impossible when 
it's in full contact with cellulose)?

-Kat

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