[GSBN] no Timber frame for Alberta house
Alex Wilson
alex at atwilson.com
Mon Sep 19 00:20:35 UTC 2011
Hello Bruce and everyone else,
Thanks so much for all the great input! Much more than I could have hoped for. I'll see my cousin next weekend and will share all this input with him. Great food for thought.
Cheers,
-Alex
Founder, BuildingGreen, Inc.
Executive Editor, Environmental Building News
On sabbatical through November, 2011
122 Birge Street, Suite 30
Brattleboro, VT 05301
802-257-7300 ext. 106
http://www.buildinggreen.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
On Sep 18, 2011, at 4:16 PM, Bruce King wrote:
>
> Howdy, all. I haven't been able to fully track all the responses, but agree with all that I've seen.
>
> Alex, it does sound like a continuous footing and sealed crawlspace might be better in the long run both for structural and thermal performance, but short of looking at site and design specifics, I couldn't say more.
>
> Thanks,
>
> Bruce King, PE
> Director of EBNet
> Ecological Building Network
> the art and science of building well
> bruce at ecobuildnetwork.org
> PO Box 6397
> San Rafael, CA 94903 USA
> (415) 987-7271
> follow us on Twitter: @EBNetwork
> blog: http://bruceking.posterous.com/
>
> On Sep 16, 2011, at 7:26 PM, sarahkh at lightlink.com wrote:
>
>> I want to respond to Alex's assumption that a rugged timber frame is a "must"
>> for dealing with the Chinook winds.
>> Timber frames are not all that stiff. The bracing of a frame -- a few short
>> braces per wall -- is far less extensive than the
>> bracing of a stud wall by diagonal board sheathing, let alone plywood. And
>> as timbers dry and shrink, some of the braces will
>> become less tight than they were at raising day. The old timber framed barn
>> I used to live in creaked in the wind. I once had
>> a conversation with Bruce King about timber frame and straw bale, and he agreed
>> that the plastered bale wall is stiffer than the
>> frame, and provides the bracing for the building if it is strong enough.
>>
>> I would conclude then that if a house is going to be slammed by powerful winds,
>> the more uninterrupted expanses of plaster
>> on inside and outsides of the walls, the better. As we discussed at our winter
>> meeting, timbers break up the plaster walls
>> quite a lot, requiring all kinds of fussing around with air fins, caulks, gaskets,
>> and the like. These would also be potential air
>> leakage points, made more significant by the strong winds pushing and pulling
>> air around the house. I'd go with a hybrid
>> approach, with roof structure held up by door and window framing and a minimum
>> of additional members inside the bale walls
>> (a la Clark Sanders, and others), and posts and beams in the middle of the house
>> helping to hold up the roof or ceiling.
>> Timber ledgers fastened to exterior walls could catch the ends of timber joists,
>> if those are part of the design. This approach
>> ought to be cheaper as well.
>>
>> I would also want to see a strong and well-cured plaster on the walls, and supported
>> on the foundation. This would be the
>> key to the house's wind resistance, in my mind. Supporting it on the foundation
>> means the house would be best off with a
>> continuous foundation at the base of the walls.
>>
>> I'm not an engineer, so other strategies might suffice, but I believe this approach
>> would be the strongest and most reliable
>> over time.
>>
>> Tying the house to the ground structurally would not only tend to make it stronger,
>> but also help make it able to weather
>> periods of no heat without freezing. This was a key design criterion of the
>> Buffalo House project in South Dakota, organized
>> by the Intertribal Council on Utility Policy and Laura Bartels. The HUD houses
>> built by the Tribal Housing Authority on the
>> Rosebud Lakota reservation were generally built on piers AND badly insulated.
>> They cost a fortune to heat in the Great Plains
>> winters, and when people were not there paying for heat, the pipes froze.
>> So the Buffalo House is a model project to show
>> that a HUD-style size and shape can be built with straw bales over a crawlspace,
>> with passive solar consideration in the
>> window design. Not only is it intended to be heated for much less cost, but
>> it is supposed to demonstrate "passive
>> survivability" i.e. not freeze when someone isn't home. Even if a homeowner
>> intends not to stop paying the heating bills in
>> the winter, this model suggests that there is a thermal advantage to putting
>> a house on the ground, and it is designed for a
>> similar climate to Alberta. (Intertribal COUP has a website for those interested.)
>>
>>
>> Thanks,
>> Sarah Highland
>>
>>
>>
>>>
>>>
>>> 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 strawba>les in the floor. All of
>> these houses had free air space between the groun>d 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 r>isk
>> 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 Albe>rta,
>> I believe that many of the SB houses
>> there are built on piers. Kim Th>ompson (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 we>nt with a full wrap instead of infill for less thermal
>> bridging and improve>d airtightness). The
>> entire floor cavity (including cantilever) is insulate>d with blown cellulose.
>> We then stacked stone underneath for a faux stone
>> f>oundation 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-la>id 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. i>f
>> 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 mig>ht 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 de>tails.
>>
>>>>
>>>>
>>>> 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 impro>ving
>> 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 si>ster's ranch in the foothills of the Rockies
>> of southwestern Alberta. He wa>nts 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 li>ke 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-fr>ame/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-husb>and,
>> 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 r>ate goes up in that region, apparently, when it's really windy
>> and people s>peculate 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 wi>th the floor
>> insulation.
>>>>>
>>>>> It's easy enough to calc spans using common charts based on estimated we>ight.
>> Considering his local soil qualities may
>> be important.
>>>>>
>>>>> I think the best owner-builder designs are the simplest ones. Keep it si>mple
>> 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 looki>ng around
>> www.balewatch.com
>>>>>
>>>>> With your permission I'd like to forward the pertinent parts of your not>e
>> 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
>>>
>>>
>>>
>>>
>>>
>>>
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>>>
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