[Greenbuilding] insulating around windows... best practice

John Salmen terrain at shaw.ca
Thu Sep 5 08:10:22 MDT 2013

I've never seen that - but so many products out there. Nothing listed on the
Canadian MSDS for the tape but the US one lists acrylate which is a contact
allergen and polyurethane foam. 


I think tape sealing the gap is more important than filling the gap as the
idea is to leave room for building movement. We do use foam guns but I do
think gaskets are the best as foam can get pretty rigid. (Trick with the
foam gun is to Vaseline the can to gun connection and after using very
tightly close up the adjustment knob and never touch it with cleaner and
then make sure it gets used once a month at least). 


Not much need for that type of filling now with exterior foam wraps. We are
securing windows and doors to the outside foam skin using taped flanges
(adding flanges to wood windows). Tied back to framing with strapping.
Leaves a flexible assembly. If it is a wood window with wood liner - the
liners are made up as part of the window (biscuit) and float with the window
in the opening.


Window details still need some work - I think ideally they should be
recessed on the exterior to minimize wind washing but its a hard detail to
work out.


From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of Alan Abrams
Sent: September-05-13 4:34 AM
To: Green Building
Subject: Re: [Greenbuilding] insulating around windows... best practice


I've heard about but never tried Tremco expanding foam tape.  It comes off
the roll very thin, and sloowwwly expands.  You apply it to the window
perimeter, and you have a few moments to slam the window in place, and level
and square it up, before the Tremco swells to seal the gap.  If you run into
a problem with the opening, or have to stop and take a leak, the foam
expands larger than the opening, and you have to scrape it off (at what, a
buck a foot???) and start over. 




On Thu, Sep 5, 2013 at 3:00 AM, Reuben Deumling <9watts at gmail.com> wrote:

I like backer rod. My method has evolved into stuffing the appropriate
diameter backer rod from the outside and from the inside around the
perimeter of the window. Done carefully I convince myself that I'm creating
some dead air space in between the two foam layers. 
Are there better ways of doing this? 
I am aware of and used to use a foam gun. But I never can seem to make sure
to clean the gun when I'm done and so the next time I have to buy the
expensive acetone cleaner and take the damn thing apart again. Which is one
of the reasons I've switched to backer rod. 


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Alan Abrams
certified professional building designer, AIBD
certified passive house consultant, PHIUS

certified passive house builder, PHIUS
Abrams Design Build LLC
sustainable design for intentional living
cell     202-437-8583
 <mailto:alan at abramsdesignbuild.com> alan at abramsdesignbuild.com
 <http://www.abramsdesignbuild.com/> www.abramsdesignbuild.com

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