[GSBN] Question about SB insulation at foundation/ceiling

Wed Jan 25 00:37:52 UTC 2012

David maaaaate– you can’t guarantee that the bales won’t rot.

I agree with Bruce.

You’re asking for big trouble. (Hope you have lots of insurance cover!)

Strawbales should only be used in walls –using strawbales under floor have
too many damp issues.

I’d like to hear a response from our colleague in New Zealand (Graeme) where
moisture is a real problem.

Bohdan “don’t like using bales under floors” Dorniak

Architect, South Australia

From: GSBN-bounces at sustainablesources.com
[mailto:GSBN-bounces at sustainablesources.com] On Behalf Of David Arkin, AIA
Sent: Wednesday, 25 January 2012 10:34 AM
To: Global Straw Building Network
Subject: Re: [GSBN] Question about SB insulation at foundation/ceiling

In slab on grade situations we're now using mineral wool, aka rock wool,
which is available in panels and becoming increasingly easy to get here in
the US, and it's been around for quite some time.  Roxul is one brand:
http://www.roxul.com/building+envelope/products/roxul+drainboard®

They claim that the energy used in manufacturing is recovered within three
weeks of installation.  It isn't the least expensive solution, but it is
entirely rot resistant, and it isn't petroleum.  We've also used EPS under
slabs, employing the wisdom of Buckminster Fuller, "We have more than enough
petroleum to meet our needs, if we'd only stop burning it."  Rigid foam
insulation which enables a building to need less heating or cooling is a
justifiable investment, imho.

That all said, this idea of bales under a floor - even a slab on grade -
intrigues me, and I do believe one can create a condition where the risk of
rot is minimized.  However, building occupants would need to know that
frequent (or maybe any) mopping of floors is not possible, and I'd still
prefer to see the bales considered as sacrificial.  If the bales were
staggered slightly in both directions one could have occasional piers
(roughly 2' (0.6m) o.c. in one direction and ±3'-9" (±1.15m) o.c. the other,
depending on bale size) that would take over the supporting of the floor if
the bales were to deteriorate.  

And of course John Straube beats me to the 'send' button yet again!

David 

On Jan 24, 2012, at 11:17 AM, forum at lamaisonenpaille.com wrote:

It is true that (raised) SB floor insulation are getting more popular here
in Europe but this worries me somewhat because in my pré-SB life I have seen
at least 3 floors with water 'standing' on it due to : a frozen water pipe,
a broken down washing machine and (the most fun) a friend who put a few
beers in the botom of the shower and he opened the tab so the running water
would cool the drinks while taking a siesta in our spanish hotel in my 20's.
His nap was interupted when the people below saw water comming through the
ceiling...  My moral of the story : If  don't use waterpipes in cold
countries, wash in an outhouse and be carefull when choosing your friends if
you use 'compostable' floor insulation. 
Sure, some claim that they detail in such a way that water cannot penetrate,
but I wonder how this is done in a perfect, cost effective and durable
manner. In any case, the french insurance companies made sure SB floor
insulation was deleted from our proposal for the recently approved french SB
building rules (I wonder why? ;-).

An interesting technique sometimes used in France is using a tiny fan to
blow the hot air (from below the roofing) through pipes under the slab (at a
well calculate dept) so that with the time lag this heat comes up during
winter. Seems like a clever idea to take away the heat where we don't want
it in a way it becomes available where and when we do appreciate it. I have
no details of it and there might be practical disadvantages that makes this
system less ideal than one might think...

André - fan of locally made slippers - de Bouter
France

Le 24/01/2012 19:10, Laura Bartels a écrit :

In the project I just finished, we used bagged perlite insulation over 6
inches of 3/4" washed gravel covered by a vapor/radon barrier. The perlite
was tamped, finishing at 7" for an R-value of 21.9. It is a regional
material here, minimally processed, light to transport, and non-toxic. So
far, I'm very satisfied with this choice and would like to do more with this
material. It is installed under an adobe floor with good results. I had had
conversations with Daniel Silvernail, who had also used perlite underfloor,
as well as builders in the northwest US. I know there's been some discussion
of perlite on this list which I believe I missed due to my schedule at the
time.

On a related note, I have just spent a few days with Arlene Blum, PhD and
director of the Green Science Policy Institute and learned much more detail
of the toxicity of flame retardants which are added to most foam building
insulations as well as foams in furniture. More info can be found here -
http://greensciencepolicy.org/non-toxic-building-materials. There are some
very interesting elements of this issue, one of which is that the flame
retardants not only give little reduction in burn time (as in seconds) but
also add several additional problems if a fire does occur, such as increased
carbon monoxide, soot, along with the cancer causing chemicals that are
unregulated as they do not fall under the jurisdiction of EPA or FDA, but
are mandated through building standards. And for underslab insulations,
flame retardants don't make sense anyway. 

Best,

Laura

Laura Bartels

GreenWeaver Inc.

520 S. Third St., Suite 5 

Carbondale, CO 81623
970-379-6779
www.greenweaverinc.com <http://www.greenweaverinc.com/> 

<Mail Attachment.jpeg>

We've moved to the Third St. Center 

 <http://thirdstreetcenter.net/> http://thirdstreetcenter.net/

A community place promoting inspiration, sustainability and creative
exchange

On Jan 24, 2012, at 10:09 AM, Derek Roff wrote:

It would be nice to be able to choose from a richer range of choices than
the functional, but high embodied energy, toxic, petroleum foam vs. a more
benign product that may rot.  Making a "lesser of two evils" choice
guarantees choosing something evil.  It would be great to have ten choices
with generally positive attributes, but we do have at least one additional
option.  As I understand it, Roxul Drainboard rigid mineral fiber insulation
is more environmentally benign than petroleum foam, and more resistant to
destruction from human, insect, and rodent activities.  One of the comments
in the links that Joyce gave indicates that Roxul Drainboard was selling at
a lower cost per R-value, as well, at that time in early 2011, in Virginia,
if I remember correctly.  I've never used it.  Any comments from someone who
has?  Any other alternatives that you favor?

Derelict

Derek Roff

derek at unm.edu

On Jan 24, 2012, at 9:32 AM, Bruce King wrote:

The idea of using any cellulosic material at or near grade just makes me
nervous and ill.  We have a world of experience telling us that wood,
paper-faced gypsum board and straw don't last long there, or anywhere near
there.  Recall Kim Thompson's well-documented problems using bales between
floor joists over a Nova Scotia crawlspace.

But how, then, to insulate?  I guess I would argue for the use of a
naturally-occuring substance that can make a durable and also effective
insulator in the presence of moisture, namely petroleum.  It takes a bit of
unpleasant processing to turn oil into foam (that is, something that entraps
air which is the real insulator), and god knows we need to improve on the
weird stuff currently on the market.  But if there is any good use for
petroleum, this is surely one.  Not for our cars, not for crappy plastic
packaging & throwaway junk, but for effective, durable, reuseable
insulation.

Or anyway I'm still waiting for a viable "natural" ground insulation
suggestion that isn't a super labor intensive fuss job.

Shredded plastic bags, anyone?

Thanks,

Bruce "Oil gladly pay you Tuesday for some polyisocyanurate today!" King

On Jan 24, 2012, at 8:08 AM, Frank Tettemer wrote:

Hi all,

I have just received a message from the designer of the yoga centre, that I
was busy criticizing in my previous post.
The Sivananda Yoga Centre is still alive and well over a decade later.

I apologize to the GSBN group, and to Michel Bergeron, for handing down that
mis-information about the Sivananda Yoga Centre. Michel has had no such
reports of mold problems, and as the designer, he would certainly be the
first to hear about it.  It takes a foolish commnet from someone like me, to
deeply upset the credibility of straw bale construction. And worst of all,
this negative comment coming from a straw bale builder!

There's a strong lesson in all this for me, to examine all my sources of
information, and to not speak about things of which I have no first hand
knowledge.

Deeply chagrined, deeply humbled,

Frank Tettemer

On Jan 24, 2012, Derek Roff wrote:
I'm not sure if this discussion is still alive on the linked site that Joyce
posted.  The newest posting is just about a year old, but perhaps the
discussion will warm up again.  Bruce King posted a comment last year, when
the discussion was current.

Something that wasn't mentioned in the article or comments is the naive
assumptions regarding the effective insulation value of the strawbale waffle
slab design, even before the bales start to rot.  The assertion is made, and
not challenged, that the under-slab strawbale insulation would provide R-50.
Whatever number we accept as the insulative value of each bale, the thermal
bridging of the concrete in the matrix would cut the effective insulation of
the waffle slab design dramatically.  Thermal bridging isn't a problem with
the design sketch that Joyce included, but the risk of rot probably remains.

There is an alternative approach that uses bales as floor insulation, but
above grade.  After a European Straw Building gathering a few years ago,
traveling with Catherine Wanek, I visited SB buildings in half a dozen
countries, including several that used strawbales in the floors, to meet
Passiv Haus design goals.  All of these structures were build on piers, so
that the bales were above grade and isolated from the moisture concerns that
afflict buried bales.  Here is a link to one example, the S-Haus in Austria.

http://www.s-house.at/presentations.htm

Bale-on,
Derelict

Derek Roff
derek at unm.edu <mailto:derek at unm.edu>

On Jan 23, 2012, at 10:40 AM, Frank Tettemer wrote:

Well now,
that is pretty interesting.
Thanks, Joyce, for sounding the alarm.

Before I actually (physically and personally), had built any SB houses, I
naturally ass-u-me-d that bales in the floor and ceiling were a good idea.
It is too bad that the article in finehomebuilding references the
experimental work of Michel Bergeron, of ArchiBio, in the ground-breaking
book of Steen/Steen/Bainbridge/and Eisenberg.  I love the book, and it is
what gave me hope for the idea of burying bales below grade.

Fortunately for me, Linda Chapman, (archi. from Ottawa), talked with me
about doing this in the early nineties.
She had boldly gone where no one had gone before. And the floor rotted.

And there was the evidence from the huge three-story yoga retreat centre,
built in Quebec,
which was such a rotten embarrassment, that I won't mention it anymore.

Then there's the theory that if you stick each bale into a garbage bad
before you bury them under the floor ...
just to say I did, I took a bale, put it into a garbage bag, and placed it
into a weather-protected shed, to see what happened.
First of all, it took three trys with the garbage bad to place a bale into
it, without it being punctured by straw.
Secondly, during the summer of 2000, which was a fairly wet year, the bale
self-composted, with out having had a drop of rain on it. I imagine that
relative humidity was all it took. It was full of mildew in two months time.

I have to say, though, that the idea is so intriguing, that it captures the
imagination of quite a few clients, who would wish me to design a foundation
using straw bales.
Maybe it's just a stupid idea, here in a climate with huge weather extremes,
(+35C to -35C), and many days of damp rainy weather?
Maybe all the ideas have not been tried as yet?

Frank

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Ecological Planning & Design

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