[Greenbuilding] Exterior insulation retrofit

[Kat]

Don't know what everyone else thinks of these and I don't know if the 
pdf will come through to the group, but attached is a FHB article from 
Jan 2010 that makes suggestions for creating R-40 walls - some of which 
are suggestions for retrofits.

-Kat

Sam Ewbank wrote:
> Rob
> The curtain wall idea is intriguing.  Do you know of a source for the 
> sheet metal clips or similar?  
>
> This also got me thinking about a Larsen Truss style retrofit where 
> you cut off the roof over hang, wrap the walls and roof with trusses 
> (offset to the studs to stop thermal bridging but attached at the rim 
> joist and wall plates) and then filling the cavities with cellulose. 
> You would likely need some sort of sheathing on the exterior but maybe 
> a good weather resistive barrier would work and your horizontal 
> nailers for the shake siding.
> You could then create a continuous air/vapor thermal barrier on the 
> exterior of the structure.
> Another idea would be to use I-joist attached similarly, this would 
> then allow you to use a batt product like Roxul on walls if so inclined.
>
> Sam
>
>
>
> On Thu, Apr 28, 2011 at 2:01 PM, RT <Archilogic at yahoo.ca 
> <mailto:Archilogic at yahoo.ca>> wrote:
>
>     On Thu, 28 Apr 2011 08:45:46 -0400, <bill.allen at verizon.net
>     <mailto:bill.allen at verizon.net>> wrote:
>
>
>         Add external insulation....rigid styrofoam.
>
>
>
>     And of course, there is the non-plast-eccchhh! foam approach where
>     one wraps the existing sheathing to do a first class job of
>     air-sealing and then install short 2x3 or 2x4 standoffs over,
>     using sheet metal clips and then hang curtain wall studs and
>     sheathing off of the end of those stubs to create a new insulation
>     cavity with the capacity to hold superinsulation levels of a
>     blown-in non-plast-ecchhh!
>
>     Avoiding the use of the foamed plast-eccchh! will usually more
>     than pay for the cost of the wood for the curtain wall framing and
>     higher levels of insulation, but at a penalty in terms of extra
>     wall thickness which may be a problem in tight urban situations.
>
>     But what about the thermal barrier in the roof especially if the
>     roof volume is inhabited space ?
>     ie One can only fill up a 2x# rafter cavity with # inches of
>     insulation.
>
>     If that's the case, then using the same stand-off idea on the roof
>     to turn the existing rafters into parallel chord trusses with an
>     insulation cavity of ## inches while at the same time raising the
>     eaves line to accommodate the incremental wall thickness would, as
>     Martha Stewart might say "Is a Good Thang".
>
>
>
>     -- 
>     === * ===
>     Rob Tom
>     Kanata, Ontario, Canada (where a raucous windstorm (probably blown
>     up from the USA) has knocked out the hydro (aka "electricity")
>     < A r c h i L o g i c  at  Y a h o o  dot  C A >
>     (manually winnow the chaff from my edress if you hit REPLY)
>
>
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