[Greenbuilding] Exterior insulation retrofit

[RT]

On Thu, 28 Apr 2011 08:45:46 -0400, <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 >
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