[GSBN] straw/cell assembly

[Frank Tettemer]

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