[GSBN] straw/cell assembly

[ejgeorge at riseup.net]

Hi Frank,

Fire in that location has been one of the main points of discussion  
(along with critters and moisture). Technically, this meets NY state  
fire code since the exposed bale surface is buried in the wall  
assembly, but the idea of either dipping the exterior sides of the  
bales or spraying with slip have been suggested, (or even a quick  
rough coat between studs).

In the end, Ben summed it up:
"Seems like if there was a fire and the sideing was gone and the AB  
[air barrier] burnt and
the cellulose falls out, you are worried about the straw?????  Isn't is a
lost cause at this point?  More or less...."

ej


Frank Tettemer <frank at livingsol.com>:

> ej George,Thanks so much for posting that info, and opening a  
> discussion about this wall system.
>
> I have been watching, with keen interest, as Deva, Aaron, and Ben  
> have been developing their work.  Deva brought slides of that  
> construction-in-process to a presentation to the Natural Building  
> Conference, here in Ontario.  Seeing the process is believing.  I  
> don't see any reason that this wall assembly couldn't meet the  
> requirements, and assist the development, of a passivehaus wall  
> system, for cold climates such as what we live in here in Canada.
>
> Most importantly, this system can produce a wall that works for  
> extremely high R-values, with a very minimum of petrochemical use!
> While I admire the goals of passivehaus, (especially when the  
> temperature drops to -30 outside for extended periods), I've never  
> been comfortable with the idea of promoting the use of eleven inches  
> of foam insulation, produced from toxic tar sands products, to "cut  
> down" on the use of heating fuels, (such as natural gas, coal, and  
> oil).
>
> My only question of concern in this system, which may or may not  
> have already received testing, is the idea of using fire-retarding  
> renders on only one side of the bales.  It seems a bit optimistic to  
> think that bonding the exterior side of the bales with cellulose  
> will act as a fire stop for the bales.  I know that commercial  
> cellulose, (recycled newsprint), is a fine product, and I have used  
> it extensively in nearly all of my builds, for over a decade. But at  
> the same time, I am skeptical of the lasting affects of the borates,  
> mixed into the cellulose, to act as a continual fire retardant.
>
> How much more difficult would it be to plaster the exterior surface  
> of the bales, between the studs, before closing up the framed  
> cavity, and blowing in cellulose?
>
> Thanks to the NBNE folks for this contribution towards cold climate  
> construction.
>
> Frank
>
> -- 
> Frank Tettemer
> Living Sol ~ Building and Design
> www.livingsol.com
> 613 756 3884
>
> There's a discussion on the NBNE (Natural Builders NorthEast) list about
>  building a load bearing 2x4 stud wall outside of the bale walls and
> filling it with cellulose against the bales with typical plaster only on
>  the interior wall.
>
>
>
> Deva Rascusin and Ben Graham threw this "straw/cell" idea out a year
>  or two ago, and have already done two projects and are working on a
> third.  Aaron Dennis is currently designing one with Cornell U
> Sustainable Design.
>
>
>
> One of several advantages of this system is the ability to build in
> cold climates at any time of year since the exterior plaster is replaced
>  by the 2x4 cellulose filled wall.
>
>
>
> The question is whether there is any logical reason this system  
> wouldn't work.
>
> The 2x4 wall would be  built conventionally to take all structural loads.
>
> The cellulose would work as a fire resistant barrier and the
> sheathing, moisture (air) barrier and siding would keep out the moisture
>  and critters as well as they do in conventional construction.
>
>
>
> In our discussion, Derek mentioned that a similar idea has been
> discussed (not sure if just in theory or actual experience) at last
> year's ISBConference, so I thought some of you might have additional
> comments or insights.
>
>
>
> Attached is a photo from Deva  and Ben of a sample wall they built
> and two images of a drawing from Aaron of the wall assembly.  Note:
> Aaron was considering in his drawings the merits of eliminating the
> sheathing and bracing the wall with let - in bracing, but that is a side
>  discussion for any framed wall and not specifically relevant to the
> straw/cell assembly.
>
>
>
> Thanks much!
>
>
>
> ej
>
>
>
>
>
> ej George, CSBA
>
> Tugley Wood Timberframing
>
> 6301 Searsburg Road
>
> Trumansburg, NY 14886
>
> tugleywood.com
>
>
>
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