[GSBN] Straw on edge with stick (stud) frame

ejgeorge at riseup.net ejgeorge at riseup.net
Thu Jul 7 08:55:32 CDT 2016


Hi Jim,

"StrawCell systems" was a topic at our NBNE gathering in March. In 
addition to Jacob, Chris Magwood has also experimented with it, and 
Aaron & I (Tugley Wood) used a version on a build two years ago. While 
we all used strawbale to the interior and cellulose filled studs to 
exterior, there was definitely a fair bit of variety in implementation 
(such as strategies for blowing the cellulose, detailing, etc). I will 
try to find my notes of the talk and send to you.

If memory serves correct, the general concept has been bandied about at 
NBNE gatherings at least since Clark Sanders hosted at Hartwick which 
was clear back in 2009. At this year's meeting we all agreed it was 
Jacob who first suggested it - and kept suggesting despite the initial 
“are you crazy?” reaction of the rest of the group (none of us could get 
past the idea of jettisoning the exterior plaster layer). Kudos to him 
for continuing to push the boundaries!

Also, many thanks to Martin for including this in the updated code 
proposals!

ej

ej George
Tugley Wood Timberframing
6301 Searsburg Road
Trumansburg, NY 14886
607-387-3602





On 2016-07-05 18:27, martin hammer wrote:
> Re: [GSBN] Straw on edge with stick (stud) frame Hi Jim,
> 
> The system Jacob mentions (invented?) uses "dense-packed" cellulose
> insulation between framing, and tight against the already stacked
> bales. I included this in a recent code change proposal for Appendix S
> - Strawbale Construction in the International Residential Code (IRC).
> You can see the added language underlined in the section below. It was
> approved in April and will be in the 2018 IRC. (The IRC is the model
> residential code in the U.S.)
> 
> Jacob, and others who practice this method in the northeast U.S.
> wanted this explicitly allowed in the U.S. SB code because it was
> being or they feared it being questioned or disallowed by building
> officials.
> 
> AS104.2 PURPOSE, AND WHERE REQUIRED. Strawbale walls shall be finished
> so as to provide mechanical protection, fire resistance and protection
> from weather and to restrict the passage of air through the bales, in
> accordance with this appendix and this code. Vertical strawbale wall
> surfaces shall receive a coat of plaster not less than 3/8 inch (10
> mm) thick, or greater where required elsewhere in this appendix, or
> shall fit tightly against a solid wall panel or dense-packed cellulose
> insulation with a density of not less than 3.5 pounds per cubic foot
> (56 kg/cubic meter) blown into an adjacent framed wall. The tops of
> strawbale walls shall receive a coat of plaster not less than 3/8 inch
> (10 mm) thick where straw would otherwise be exposed.
> 
> Related to this I've used 2x4 studs at 46" (117 cm) with stacked
> 3-string bales on edge in between. The studs nestle into the
> curved-corner joint between stacks of bales and stacks fit tight at
> bale ends.  A minimal roof bearing assembly the width of the bales
> bears on the studs (which are on the outside wall face only). I call
> it a "light post and beam" system.
> 
> David Arkin (on this list) and others have used a similar system, but
> with TJIs ('truss joists') installed vertically like studs, with bales
> stacked between them. Unlike the system I've used, it has a vertical
> framing member both inside and outside (the 'flanges' of each truss
> joist) and with great out-of-plane strength, allowing for tall walls
> or other high out-of-plane demand designs. It has minimal thermal
> bridging through the OSB web of each truss joist.
> 
> These systems don't do one thing I think you're trying to achieve.
> That is, adding a layer of insulation to the stacked straw bales. I
> like that you use wool between the studs in your system, as long as
> it's packed tightly against the bales and framing. Trying to avoid
> uninterrupted vertical spaces that could be a "chimney" for fire.
> 
> Best.
> 
> Martin
> 
> Martin Hammer, Architect
> 1348 Hopkins St.
> Berkeley, CA  94702
> 510-525-0525 (office)
> 510-684-4488 (cell)
> 
> On 7/5/16, 8:45 AM, "Jim Carfrae" <jim.carfrae at plymouth.ac.uk> wrote:
> 
> Thanks Bruce
> 
> I'm adding an extra layer of insulation to keep up with current
> standards like PassivHaus (I don't build PassivHaus, but clients like
> to hear that you're using similar levels of insulation….)
> 
> Unless anyone else wants to chip in, I'll reference Jacob as the
> originator.
> 
> Jacob, If I continue using a version of this method would you like to
> be credited in the documentation for planning approval etc?
> 
> Jim
> 
> FROM: Gsbn <gsbn-bounces at sustainablesources.com> on behalf of Bruce
> EBNet <bruce at ecobuildnetwork.org>
> DATE: Tuesday, 5 July 2016 at 16:10
> TO: Global Straw GSBN <gsbn at sustainablesources.com>
> SUBJECT: Re: [GSBN] Straw on edge with stick (stud) frame
> 
> Jim --
> 
> I'll chime in here just to say that I first heard of the system from
> Jacob, so as far as I know he deserves credit.  (Thanks, Jacob!).  You
> can add other insulation fairly easily, but generally don't need to,
> other than to plug the thermal bridges created by the wood studs where
> there is no straw.
> 
> Bruce
> 
> On Jul 5, 2016, at 7:11 AM, Jim Carfrae <jim.carfrae at plymouth.ac.uk>
> wrote:
> 
> Hi Dan
> 
> My interest was mainly to do with combining the structural simplicity
> of a stick frame with the potential for significant extra insulation,
> as in the StrawCell example.
> 
> Does your system involve much additional insulation?
> 
> In the UK I have been using a 4 by 2 frame with wool as the insulation
> between the studs. This combines with the straw to reduce the U value
> from a nominal 0.16 W/m2K for a rendered straw wall down to 0.11 W/m2K
> for the hybrid wall.
> 
> Jim
> 
> FROM: Gsbn <gsbn-bounces at sustainablesources.com
> <mailto:gsbn-bounces at sustainablesources.com> > on behalf of Dan Smith
> <dan at dsaarch.com <mailto:dan at dsaarch.com> >
> DATE: Tuesday, 5 July 2016 at 14:48
> TO: Global Straw Building Network <gsbn at sustainablesources.com
> <mailto:gsbn at sustainablesources.com> >
> SUBJECT: Re: [GSBN] Straw on edge with stick (stud) frame
> 
> Hi Jim,
> 
> We've been working with a similar system of bales "on end" between 2x
> studs at 2' o.c., with ply/fiber board on the exterior, and have a
> large addition to an adobe house planned to use it soon, working with
> Bruce King as engineer.  I'd be happy to chat as well and send
> details.
> 
> Dan Smith
> 
> d s a architects
> 1107 Virginia Street | Berkeley | CA 94702
> ph. 510.526.1935 | www.dsaarch.com <http://www.dsaarch.com/>
> 
> On Jul 5, 2016, at 6:35 AM, Jim Carfrae <jim.carfrae at plymouth.ac.uk
> <mailto:jim.carfrae at plymouth.ac.uk> > wrote:
> 
> Hi Jacob
> 
> Thanks for the response.
> 
> I have been experimenting with a version of this technique myself, and
> I principally wanted to find out if:
> 
> 1)    I was using someone else's 'protected' design.
> 
> 2)    It might feature in an upcoming academic paper, and I wanted to
> know who to reference as the originator.
> 
> The post that I saw had a photo of a demonstration wall section and a
> couple of SketchUp drawings - Was that you?
> 
> Cheers,
> 
> Jim
> 
> FROM: Gsbn <gsbn-bounces at sustainablesources.com
> <mailto:gsbn-bounces at sustainablesources.com> > on behalf of Jacob
> Racusin <buildnatural at googlemail.com
> <mailto:buildnatural at googlemail.com> >
> DATE: Tuesday, 5 July 2016 at 13:39
> TO: Global Straw Building Network <gsbn at sustainablesources.com
> <mailto:gsbn at sustainablesources.com> >
> SUBJECT: Re: [GSBN] Straw on edge with stick (stud) frame
> 
> Hi Jim,
> 
> We've been doing this technique for a few years now, in a few
> different ways. We coined a term "StrawCell" to describe the hybrid
> system, a web search for that term should turn up a few blog posts and
> videos. I'm not sure if I was the originator of the post, as others
> have been using this technique as well, but I'd be happy to chat
> further.
> 
> Cheers,
> 
> Jacob
> 
> On Mon, Jul 4, 2016 at 4:58 AM, Jim Carfrae
> <jim.carfrae at plymouth.ac.uk <mailto:jim.carfrae at plymouth.ac.uk> >
> wrote:
> 
> Hello
> 
> A couple of years ago details of a bale wall system using bales on
> edge against a stick frame were posted here.
> 
> I can't find the original post, and would like to contact the
> originators of the idea.
> 
> Can anyone out there help?
> 
> Jim
> 
> Dr Jim Carfrae
> 
> Environmental Building Group
> Room 302 Roland Levinsky Building
> School of Architecture, Design and Environment
> Plymouth University
> Drake Circus
> Plymouth PL4 8AA
> 
> 07880 551922
> 
> jim.carfrae at plymouth.ac.uk <mailto:jim.carfrae at plymouth.ac.uk>
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