[GSBN] prefab strawbale

cmagwood at kos.net cmagwood at kos.net
Sun Aug 2 21:23:04 CDT 2009


I've been using a pump for a long time too, and it's great. But the
plaster still needs to go on in at least two coats, and requires skilled
or at least semi-skilled trowelers to make it look good. And weather is a
huge factor too.

I'm in no way dissing site built straw bale. I love it, and will continue
to do it. But after 15 years of site building, it's pretty clear to me
that the time and cost will always be slightly higher than for
conventional construction. We pulled off these prefab walls for about half
of what any framing crew could manage, and that's a big, big savings. And
it was our first real run, too. The savings will only get better as it
gets refined.

But I don't see this as matter of one system versus another. Prefab can
deliver straight, square, true walls to clients who don't want to hand
build but still want good insulation and low EE materials. Or the walls
can be delivered to builders/developers who want to do something greener
but can't see the cost advantage to training workers or developing
entirely new building systems. They can buy these panels, save money and
decrease the time it takes to build. But prefab will never deliver the
beauty and satisfaction of hand crafted, hand plastered homes. Two
different systems for two different needs, no competition required!


> Hi All,
> I have been interested in prefab wall panels for some time, but have
> difficulty finding the appropriate time and skill savings. My son Brad has
> a
> render pump that will pump up to 60 square meters an hour at 20mm thick.
> He
> works with the owners and their volunteers to keep their costs down. It is
> often necessary to have two mixers to keep up with the machine, but at 1
> square meter per minute it is pretty quick.
> Regards
> Brian
> Anvill
> -----Original Message-----
> From: GSBN-bounces at greenbuilder.com [mailto:GSBN-bounces at greenbuilder.com]
> On Behalf Of cmagwood at kos.net
> Sent: Friday, 31 July 2009 8:40 PM
> To: private, with public archives) Global Straw Building Networ
> Subject: Re: [GSBN] prefab strawbale
> John,
> Most of the cost and time savings with the prefab panels we're doing come
> from eliminating the site plastering. The poured walls are done in a
> single coat, poured "sidewalk style", both sides of the panel at one time.
> There is no way even our best practiced spray crew could do two coats to
> two sides to a perfect finish in under an hour for an 8ftx8ft panel. Plus,
> the plaster can be applied in any weather and can cure away from sun, wind
> and gravity pulling things down the wall.
> After lots of experiments, we decided not to cast door and windows into
> the panels. Instead, we panelize the sections of the building between
> openings, and then frame in the openings once the panels are installed. In
> the case of the building we just did, those sections don't have any bale
> in them. Instead, we framed out storage bins/benches at the same width as
> the bale walls.
> We include a single stud at the edge of each panel, and the framed
> sections are attached to these studs. I can send you the plan details if
> you want. We typically don't meet shaky California criteria here in
> Ontario, but I'm sure the system can be adapted to suit.
> Chris
>> That's interesting info, Chris, particularly your construction costs.
>> Maybe
>> we should try something like that!
>> I'm not clear how, with a module that's pre-plastered, you tie modules
>> together and make them weather-tight as well as structurally sound
>> (don't
>> forget, our ground shakes violently now and then).
>> It seems that your 'poured' walls are simple and easy for unskilled
>> builders.   What would be the difference if you installed pre-fab walls
>> w/o
>> plaster, and a professional crew did the plastering as normally done?
>> John "Beyond Fab" Swearingen
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