[GSBN] [nbne] Re: Fwd: Question on straw-bale house foundations

Thu Sep 15 21:48:26 UTC 2011

A majority of the strawbale houses, built to the Passiv Haus standard, that I visited in Europe a couple of years ago, were built on piers.  They had massive insulation in the floors as well as the walls, usually with strawbales in the floor.  All of these houses had free air space between the ground and the top of the piers.  I asked whether this was a contradiction with the goal of maximum energy conservation.  The reply was that the moisture risk created by blocking air flow is a serious consideration, and sufficient insulation takes care of the energy loss problem.  

Although Canada's maritime provinces don't have the extreme weather of Alberta, I believe that many of the SB houses there are built on piers.  Kim Thompson (sp?) may be able to tell us.  

Derelict
Derek Roff

On Sep 15, 2011, at 12:54 PM, ejgeorge at riseup.net wrote:

> Hey Mark & Alex,
> 
> That's what we did for our house. Pier foundations with posts sitting on the piers but the floor cantilevers out a bit to hold the bale walls (we went with a full wrap instead of infill for less thermal bridging and improved airtightness). The entire floor cavity (including cantilever) is insulated with blown cellulose. We then stacked stone underneath for a faux stone foundation to 1) cut wind from blowing underneath and 2) aesthetics.
> 
> You can see some of the details in photos on Aaron's website:
> http://www.tugleywood.com/
> (under photos, under Dennis-George House)
> 
> It certainly was the quickest and cheapest option, but has some cons too, including all the general cons of uninsulated crawlspaces such as critters and convective heat loss under the floor (though I have to say, the dry-laid stone around the perimeter did a surprising job cutting that down).
> 
> Also, I don't think it's as sturdy as a full foundation would be - e.g. if someone really slams a door or the washing machine gets unbalanced on the spin cycle, you can feel the whole house vibrate for a second. That could be partially due to the height of our piers (only 16" or so on one side of the house but 3 1/2' or so on the other as the grade slopes down). This might be more significant when considering your cousin's wind extremes. We're somewhat exposed on a plateau and get some good winds, but nothing near the extent he'll be dealing with!
> 
> Feel free to contact Aaron & I if you have more questions or want more details.
> 
> 
> ej
> 
> ej George, CSBA
> 
> 
> 
> Quoting "Mark Piepkorn" <duckchow at potkettleblack.com>:
> 
>> Hi folks,
>> 
>> A question or two from Alex Wilson, who some of you know. If you don't, see
>> http://www2.buildinggreen.com/about/people/alexwilson
>> 
>> I attempted to write a brief synopsis here of his contributions to improving the built environment starting way back before "green" was a word that went with "building," and failed utterly. Suffice it to say that he's more than earned our most thorough and considered responses. Please be sure to CC him at alex at atwilson.com
>> 
>>> My cousin Allyn is considering building a timber-frame/straw-bale house on a piece of land he owns in Alberta, Canada. It is land adjoining his sister's ranch in the foothills of the Rockies of southwestern Alberta. He wants to build it really cheaply and was thinking that he might save money by avoiding a full perimeter foundation--and going with piers or something like that. But I don't see how he would support the straw-bale walls in this case.
>>> 
>>> Any thoughts on that? Have you ever heard of someone doing that?
>>> 
>>> Any resources I might recommend to him on building a low-cost timber-frame/straw-bale home? Or any really neat designs you've seen?
>>> 
>>> The Chinook winds there are wicked, so I think a rugged timber frame is an absolute must with straw-bale. Right near the ranch, they've recorded a _full week_ where the steady wind _never dropped below 60 mph_ and a full hour where the steady wind never dropped below 100 mph!
>>> 
>>> My cousin Lucy (Allyn's sister, who owns the ranch), with her then-husband, built a timber-frame with in-fill straw-bale walls maybe 25 years ago, and as far as I know it's working great. The bale walls are a huge benefit in sound deadening. With the very strong Chinook winds in the spring, the constant noise of the wind can drive people crazy--literally. The suicide rate goes up in that region, apparently, when it's really windy and people speculate that noise is the main factor.
>>> 
>>> Thanks for any thoughts and suggestions you can share.
>>> 
>>> Hope you are well.
>>> 
>>> Cheers,
>>> 
>>> -Alex
>>> 
>>> 39 Leonard Road
>>> Dummerston, VT  05301
>>> /On sabbatical from BuildingGreen, Inc. through November, 2011/
>>> 802-257-0019 (H)
>>> 802-579-4858 (C)
>>> www.atwilson.com <http://www.atwilson.com>
>>> Twitter: http://twitter.com/atwilson
>>> 
>>> /"Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist." Kenneth Boulding, circa 1980/
>> 
>> 
>> Strawbale on piers is doable. It's a reasonable choice for budget-minded owner-builders, especially if they have big wood for the floor sills as a readily available local commodity. The thing with that scheme is dealing with the floor insulation.
>> 
>> It's easy enough to calc spans using common charts based on estimated weight. Considering his local soil qualities may be important.
>> 
>> I think the best owner-builder designs are the simplest ones. Keep it simple and well thought through. Don't wanna be building some fancy folly for years to come; get it over with and get on with life. He might enjoy looking around www.balewatch.com
>> 
>> With your permission I'd like to forward the pertinent parts of your note to a small email list populated with a raft of strawbale hotshots.
>> 
>> I hope the sabbatical is doing wonders.
>> 
>> 
>> Mark
>> 
>> 
> 
> 
> 
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Derek Roff
derek at unm.edu