[Greenbuilding] Greenbuilding Digest, Vol 12, Issue 4

[JAY WALSH]

Hi All,

Great comments about blowing cellulose. 

Jefro, I see in your latest message that you are dealing with some large open
bays, approx 8' x 10' x  9-1/4". Trying to dense pack this large cavity will
be extremely difficult and there is a good chance you will get settling over
the years. We are just finishing up a LEED for Homes project which used a
larson truss outer wall which created the same type of cavity you describe
with your double wall. We created bays by using the same fabric used for the
dense pack stapled over each of the larson trusses creating bays 24" in width.
In your case this fabric would be attached between the outer and inner studs.
Not sure what your stud spacing is but I would not exceed 24" in width for the
bays. This worked very well on this project and achieved a good dense pack.

Good luck with the project

Jay Walsh
Center for Ecological Technology


Original Message
Date: Sat, 02 Jun 2007 11:38:46 -0700
From: Jefro <jefro at jefro.net>
Subject: Re: [Greenbuilding] Cellulose blowing tools/techniques
To: Greenbuilder list <greenbuilding at listserv.repp.org>
Message-ID: <4661B936.7070707 at jefro.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Very cool monograph, Bob, thanks!

One more q... what if the wall doesn't really have "cavities" or
"bays"? My walls are made up of two 2x4 walls, interior and exterior,
on a 2x10 plate, 8 feet high. Each "bay" is a maximum 10 feet wide, as
that is the county's requirement for fire blocking horizontally. There
are also vertical stops at all of the window/door openings. In each
10-foot-max "bay", though, there are several double studs separated by
2" of air.

Following your advice, would it make sense to create a hole between each
stud and treat it as a closed bay, assuming the overflow will fill up
the 1.5" x 2" space between studs? Or should I maybe staple some mesh
in there before covering with sheetrock, thus creating a bay to fill
with cellulose but specifically not creating a thermal bridge?

thanks again