[Strawbale] re: window construction

[Robert Tom]

On Fri, 18 Apr 2008 13:57:24 -0400, Jeff Ruppert <jeff.ruppert at gmail.com>  
wrote:

>  This area would add approximately 15 sf of
> "bridge" area. R-11

> The total may be around 1% of the wall system area


Jeff;

I haven't read your posting with any sort of scrutiny yet (perhaps later)  
but I will say that the biggest problem with thermal bridges IMO is not  
the percentage of the wall that they constitute (and the increased heat  
loss they produce) but rather, that thermal bridges have the potential to  
create spots where condensation is likely to occur (in Cold Climates). If  
that condensation was not anticipated and accommodated with appropriate  
detailing, there *will* be problems.

The "R-11" reasoning looks suspect too (on the surface). While it may be  
true that  from one edge of a buck to the other there might be R-11 in  
total, conduction (and the dew point for condensation) will not be so  
polite as to happen at the end points of the section.

On the subject of treating plastered bale walls like SIPs when cutting out  
window openings and WRT Jeff's question:

> Rob, how many windows have you cut out yourself?

My answer would be "none" on a SB walls but plenty on other sorts of wall  
systems.

I've lived enough and learned enough that I don't feel that it's necessary  
to try everything at least once in order to know whether or not it's a bad  
idea.

For instance, I've never tried building a parapetted "Santa Fe"-style SB  
house in Ontario either but I can say with confidence that it's a BAD idea  
that I wouldn't bother pursuing.

I've never tried building a below-grade SB-insulated waffle slab either  
and I can say with confidence that it's a BAD idea that I wouldn't bother  
pursuing.

Flashing and sealing properly is a sequential process like shingling a  
roof.
Trying to slip in proper flashings after the cladding has already been  
done is seldom satisfactory. The same with sealing.

-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at chaffY a h o o  dot  c a >
manually winnow the chaff from my edress in your reply