[GSBN] Straw bale at high altitudes

[John Swearingen]

At high elevations, the insulation value of the straw actually increases,
because the density of the air in the interstitial spaces of the straw and
bales decreases.  (just kidding)

There is one concern that I would have about straw walls subject to high
snow drifts.  During the spring melt, the snow next to the wall will often
thaw, turn liquid, then freeze again at night.  In effect, the wall is
wetted each day.  In areas were there is a prolonged thawing season, over
month, this could be a concern for the walls.  I haven't heard of that
being a problem, but it does seem like a possibility.

John (Into thin airheads) Swearingen


On Fri, Jul 11, 2014 at 7:49 PM, Jacob Deva Racusin <
buildnatural at googlemail.com> wrote:

>  I can't speak much to elevation here in the northeastern US - we have
> just a smattering of peaks above 4K' - but I can say regarding high ambient
> humidity, abundant rainfall, extended periods of no sun, and pretty
> dramatic cold temperatures, we've had repeated and sustained success
> building with straw bale wall assemblies - provided the detailing is
> accurate to the climate!
>
> We've built over Durisol blocks on quite a few projects.  Sometimes it
> works out great for the 14" blocks to line up with a 14" bale on edge
> (we've done this a few times to get the bales up off the slab/exterior
> grade for slab-on-grade situations).  Often, it's not that simple, and
> there is a floor diaphragm in between, or some other factor complicating
> the geometry.  This all depends on the type and location of the structural
> framing (structural bale wall v. interior post-and-beam v. exterior stud
> wall, for example), but probably the easiest solution is to frame a floor
> deck over the foundation walls, and build the bales atop the floor frame.
> This allows you to easily provide blocking where necessary in the floor
> framing to provide structural continuity, and allows you to be much more
> flexible with the planes and thicknesses of your assembly components.
> Other issues crop up, such as air-sealing and insulating the floor frame,
> and again ensuring there are clear and easily-defined load paths from the
> structural plane of the walls through the floor assembly onto the
> structural plane of the Durisol (which if memory serves is about 5-6"
> inboard of the exterior face, at the concrete core), but there are ways to
> mitigate all of these with some good design detailing.
>
> Best of luck,
> Jacob
>
>
> On 7/11/14, 11:40 AM, Misha Rauchwerger wrote:
>
>  I have a client that wants to build a straw bale house at 4000 feet in
> the Sierra Foothills.  They have been getting conflicting information about
> the wisdom of building with straw at that elevation.  In particular there
> is the concern about the effects of moisture in the wetter months, and
> possible condensation inside the walls.  They know about the need for big
> eaves, and permeable plasters, but have been swayed against the idea from a
> local green architect in town.  Please direct me to any research, or
> anecdotal evidence to support straw bale construction under these
> conditions, or maybe there is valid concern.  I have only built in the
> lower/dryer elevations on flatter sites.
>
>  They also share these concerns:
>
> Their lot is sloped, so they would likely have to build a full walk-out
> basement on the lower level, and the living space on the upper level.  This
> means that the full lower level is built of concrete (probably Faswall or
> Durisol); will they would have to build out the lower walls to match the
> width of the straw bales?  How is this disparity in wall thicknesses
> usually resolved with the least cost/impact?
>
> - With a walk-out basement, is it possible/reasonable to do a
> stepped-foundation on the lower level to minimize the amount of concrete
> used?  Or does the mixed use of concrete and post/beam and straw bale
> construction create unreasonable headaches in the building process?
>
>  Thanks everyone for your comments,
>  Misha Rauchwerger
>  builtinbliss.com
>
>
>
>
>
> _______________________________________________
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>
>
> --
> Jacob Deva Racusin
> Co-Owner
> New Frameworks Natural Design/Build
>
> Author, The Natural Building Companion
> Chelsea Green Press, 2012
>
> (802) 782-7783
> jacob at newframeworks.com
> http://www.newframeworks.com
>
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>


-- 
John Swearingen
Skillful Means Design & Construction
2550 9th Street   Suite 209A
Berkeley, CA   94710
510.849.1800 phone
510.849.1900 fax

Web Site:  http://www.skillful-means.com
Blog:         https://skillfulmeansdesign.wordpress.com
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