[Greenbuilding] Exterior insulation retrofit

bill.allen at verizon.net bill.allen at verizon.net
Thu Apr 28 12:20:26 CDT 2011


Rob,

Thanks for the references. Guess I have reading for bedtime tonight:-)

Might you be near Mt Vernon, NY?

-----Original Message-----
From: Rob Dickinson <robd at pobox.com>
Sender: robddickinson at gmail.com
Date: Thu, 28 Apr 2011 09:10:45 
To: <bill.allen at verizon.net>; Green Building<greenbuilding at lists.bioenergylists.org>
Subject: Re: [Greenbuilding] Exterior insulation retrofit

Bill,

I'm working on the same type of project, and we're right in the thick of it.

I would recommend that you check out a paper that I believe John Straube
recently put out (Feb 1) on high performance residential enclosures.  It's
very good and covers lots of practical details.  It's a good follow-up to
last years paper on high r-value wall assemblies.  It covers lots of
assemblies for ceilings, roofs, basements, etc., as well as air sealing
details for electrical penetrations, venting, etc.

http://www.buildingscience.com/documents/reports/rr-1005-building-america-high-r-value-high-performance-residential-buildings-all-climate-zones/view

Also, for attaching the foam, there is good documentation on the proper
technique and fastening specs on Green Building Advisor.  One good article
is at:

http://www.greenbuildingadvisor.com/blogs/dept/musings/fastening-furring-strips-foam-sheathed-wall

They highly recommend the FasterMaster HeadLok screws, which is what I am
going to use.   This article gives the screw spacing specs for various
thicknesses of foam, including 4".  The HeadLok screws are available in
pretty much all lengths, so they can accommodate whatever depth wall
assembly you end up with.  I needed to go with 8 1/2" screws to go through
my furring strips, 4" of foam, my new Zip System sheathing, my old 1" lap
siding, etc.

Green Building Advisor also has some videos on techniques for installing the
foam.  One detail I learned there, which probably ought to be obvious, is
the way to stagger the two layers foam at corners to create a good air-seal
there and not have a direct path to the inside/

On our project, we're re-sheathing the whole building with Zip System
panels, which are OSB panels with a built-in water-resistive-barrier already
on them.  With the Zip panels we then use a special (Zip) seam tape to
create a very air-tight assembly.   So I am doing this prior to installing
the foam.

We're also installing housewrap over the Zip boards to ensure
water-tightness at window and door openings, but that might be overkill.  Or
it might be prudent, but it adds to the cost.

With the 4" of insulation, we've divided that into two layers of 2" foam.
That way, we can tape the seams of both foam layers with the foil tape to
try and increase the air-seal at the foam layer as well.  We're also
staggering the joints of the two foam layers.

Good luck.   Please share what you learn.

Rob



On Thu, Apr 28, 2011 at 5:45 AM, <bill.allen at verizon.net> wrote:

> Hi all,
>
> I am researching a project for my single family home. Classic 1926 stick
> construction. Zero insulation in the walls...time yet again for an external
> paint job. Would really appreciate comments on the following plan:
>
> We never want to paint again...are thinking of natural cedar shingle
> siding, maybe with preservative but otherwise left natural.  Don't like the
> embodied energy in the various cement siding solutions....alternatives?
>
> While the siding is down, fill the wall cavities with cellulous from the
> outside.
>
> Replace original double hung windows with new construction insulated, R-5
> if we can afford it, windows mounted "innie" on the plane of the original
> dimensional 1x lumber t+g sheathing.
>
> Add external insulation....rigid styrofoam.  Since there is no interior
> vapor barrier (plaster on wood lathe), I am worried about the dew point
> ending up in the center of the wall...therefore, per the building science
> article, add 4" of styrofoam to the outside to keep the dew point external
> of the sheathing.
>
> Will require careful details at windows and other penetrations.
>
> Big job...has anyone done this?  Any comments on any part of the above
> would be most welcomed.
>
> Thanks,
> Bill
>_______________________________________________
> Greenbuilding mailing list
> to Send a Message to the list, use the email address
> Greenbuilding at bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
>
> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org
>



-- 
"I still find each day too short for all the thoughts I want to think, all
the walks I want to take, all the books I want to read, and all the friends
I want to see." — John Burroughs (1837-1921) American naturalist, writer

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20110428/4c078ca7/attachment.html>


More information about the Greenbuilding mailing list