[Greenbuilding] Exterior insulation retrofit

Thu Apr 28 12:29:00 CDT 2011

Thanks Sam,

Yes, finding good contractors who are willing to go the extra mile (at a reasonable cost) is hard.

Suggestions near Mt. Vernon, NY welcomed.

Yes, was planning on double (vertical and horizontal) furring layers.

Would love to use salvaged material for siding....will be on the lookout...

Bill
-----Original Message-----
From: Sam Ewbank <g.l.ewbank at gmail.com>
Date: Thu, 28 Apr 2011 12:43:27 
To: Green Building<greenbuilding at lists.bioenergylists.org>
Cc: <bill.allen at verizon.net>
Subject: Re: [Greenbuilding] Exterior insulation retrofit

Jason,
I was assuming that Bill was going to blow cellulose insulation in from the
exterior likely by drilling holes in the wall and inserting a nozzle.  It
would be nice if Roxul made  a blow-in product similar to cellulose.  I am
interested in using Roxul in place of styrofoam or Poly Iso (can't say
styrofoam now without thinking of Mr. Rob Tom's "plast-ecchh!") and the
local Orange  box store in my area has Roxul products available via special
order.   Would you recommend using the Roxul "Drainboard" product over the
Cavity Rock where battens/furring strips are going to be installed for a
rain screen siding application?

Bill, if you are going to leave the sheathing on make sure you get a good
contractor for installing the cellulose since you can easily have voids in
the wall from wiring and settling or as in the case of the house I live in
balloon framing open to the crawl space. Most rental blowers are under
powered to get a good density.  If you are taking the sheathing off than you
are open to more possibilities.
My preference on the one project I have done is to put the weather resistive
barrier over the sheathing so all the penetrations can be detailed properly
prior to the rigid insulation being installed.  I know this is what Martin
Holladay @ Green Building Advisor likes to call a "Belt and Suspenders"
approach since a wrb is not really necessary with foam.  Attention to detail
at all the penetrations and joints can't be stressed enough.
I would be curious to see your approach for the shingle siding installation
if you are using a rain screen.  It seems to me you would need to add
vertical furring strips and then horizontal strips at the nailing schedule
heights.  I have a project in the works where I would be installing board
and batten siding and figure  I would need to do something similar.
Alternative siding source would be to find a building materials re-use store
or salvage. Some Habitat chapters have a "Re-store" retail outlet or
something like Samuel Mockbee, who used some 80 Chevy Caprice windshields
purchased for $80 to do a glass facade of a building.
www.flickr.com/photos/
g_agnew/1393757857/<http://www.flickr.com/photos/g_agnew/1393757857/>

Best of Luck

Sam

On Thu, Apr 28, 2011 at 10:10 AM, Jason Holstine <jason at amicusgreen.com>wrote:

>  Bill,
>
>
> On 4/28/11 8:45 AM, "bill.allen at verizon.net" <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
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