[Greenbuilding] How green is cellulose infill? / thermal bridging?

[Keith Winston]

Hmm, then you just use (somewhat) shallow electrical boxes -- well, not 
the deep boxes anyway. That's livable. I still don't love the strapping 
under sheetrock, but it's not the end of the world..

As for cellulose, the most specifics I see suggests less than 15% 
additives to Cacoon here:

http://www.cocooninsulation.com/msds-stabilized.asp?Type=C (their other 
lines are also linkable at the bottom of the page).

It also lists the specific components, including the glue (wheat starch 
or guar gum). I had no idea it was that high. I might call and drill the 
technical folks...

Keith


Clarke Olsen wrote:
> I have built double walls like this: 2x4 framing, filled with  
> insulation, then covered inside with 1/2" foil faced foam, which is
> then strapped with 2x4's flat. All the wiring takes place in this 1.5"  
> space, using 4"x4"x1.5" boxes. Taping the foam joints will make it a  
> vapor barrier. Drywall goes up vertically, good if your ceiling is over  
> 8'. Finished wall is the same thickness as  2x6 construction. For  
> headers, I replaced the foam with 1/2" plywood, glued and nailed to  
> make a hollow (w/insulation)
> box beam. For a really well insulated house, I would frame with 2x6's @  
> 2' oc.
> Clarke Olsen
>
> On Jul 11, 2006, at 1:48 PM, Alan Abrams wrote:
>   
>> <When I did some modeling of thermal bridging in a standard 2X6 wall, I
>> came to the conclusion that a thick layer of foam insulation (1" or  
>> more
>> - I've used as much as 1.5") is a good practical way to limit the
>> effects of thermal bridging.  The second way is to use Advanced Framing
>> techniques, which reduce the stacks of framing members at places like
>> corners or intersecting walls.  >
>>
>> as an earnest student of residential building science for the past  
>> several
>> decades, I've concluded that for conventional stick framed walls, the  
>> first
>> task is water management.  And foam sheathing --without  
>> disproportionately
>> complex furring, flashing, extension jambs, caulk joints, and other  
>> assorted
>> band aids and potential leakage points--compromises that task.  This  
>> comment
>> is based on real world experience, with real world conditions.  All  
>> the r
>> value in the world is worthless if the walls leak.
>>
>> If it's true that a continuous layer of insulation is critical to  
>> thermal
>> management, it makes more sense to me, to put it on the inside of the
>> wall--perhaps even strapping 2x3's perpendicular to the studs, so the
>> bridging is limited to 1 1/2" square points.  Let the outside surface  
>> be as
>> simple and straightforward as possible, to manage water.
>>
>> Wrt to advanced framing, I've been doing much of it for years before  
>> it had
>> a name.  driving the carpenters nutz, too, doubling band boards  
>> instead of
>> conventional headers, drywall clips, single sill plates for windows,  
>> etc.
>>
>> Alan Abrams
>>
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-- 
Keith Winston
Earth Sun Energy Systems
3927 Madison St.
Hyattsville, MD 20781
301-980-6325
keith at earthsunenergy.com
www.EarthSunEnergy.com