[Strawbale] [FWD] rainscreens, straw decay

Brian Waite brian at brianwaite....uk
Sat Feb 28 13:09:11 CET 2009

Ref. Rainscreens:
When I started my design of strawbalehouse I was concerned about keeping 
moisture levels in the bales at an acceptable level and unhappy about just 
using roof overhangs to keep the walls dry because this area of the UK (the 
Lake District) is the
land of horizontal rain.  No amount of eaves overhang would be satisfactory
and a veranda would be out of place.  So I have totally covered the bales 
with clay
tiles and the chimney effect created by the ventilation air entering at 
gutter level which is one meter up and exiting at the ridge at 7.5meters 
should draw plenty of air over the
exterior of the (lime rendered) bales. This natural draw should be amplified
by any solar warming of the tiles. To see more visit 
www.strawbalehouse.co.uk and/or ask for detailed sketches from myself. 
Unfortunately, I am the first to admit, my design will have no credibility 
until I can build the prototype to prove it's predicted performance. (I have 
been fighting the planners for two years) Brian

----- Original Message ----- 
From: "RT" <ArchiLogic at yahoo...>
To: "GSBN" <GSBN at greenbuilder...>
Cc: "SB REPP" <Strawbale at listserv....org>; "Euro SB" 
<strawbale at amper....muni.cz>
Sent: Saturday, February 28, 2009 7:35 AM
Subject: [Strawbale] [FWD] rainscreens, straw decay

> ========= Forwarded from SB-r-Us AYahoogroups =======
> Hello.
> I’m a graduate student at Nihon University researching the
> interstitial hygrothermal environment of straw bale buildings in Japan.  I
> have
> several questions on a couple of different topics.
> 1.           I’m monitoring eight straw bale buildings in Japan.
> Generally, interstitial humidity and straw moisture content increases
> towards
> the exterior.  Comparing indoor and outdoor humidity levels suggest that
> rather
> than exfiltration or diffusion of indoor moisture, external moisture is 
> the
> primary cause of interstitial moisture.  I’d like to investigate the
> influence of rain screens on the interstitial environment.  It may be too
> much
> to build identical straw bale structures, but I could build two or more
> straw
> bale walls protected from any unintended moisture.  The structure of the
> walls
> would be identical except that one wall would have a rain screen.  I could
> spray the walls with a measured quantity of water (in liters per minute)
> and
> monitor interstitial relative humidity and straw moisture content.
> The recent conversation on ventilated rainscreens has been helpful.  Thank
> you.  I’m looking for construction details of straw bale walls with rain
> screens to share with an architect.  I’ve found rough wall sections in
> King’s “Design of Straw Bale Buildings”, Minke’s “Building with
> Straw”, and Chiras’ “The Natural House”.  If any one could provide
> construction details or detailed photos, I’d be grateful.  (Thank you John
> in
> Australia and André in France for the descriptions.)
> 2.           I removed samples of straw from two straw bale structures
> at our research center.  Samples of straw were taken from around five
> temperature and relative humidity sensors.  One structure has been
> monitored
> for six years, the other for two years.  The condition of the straw was
> analyzed for mold and decay.  63 times magnification revealed fungal
> hyphae in
> what was to the naked eye clean straw.  A Yamaco MT-700 C-N Corder was
> used to
> measure total carbon concentrations.  As fungi digest straw, they consume
> the
> carbon in the straw and give off carbon dioxide.  The percentage of total
> carbon in the straw should, in theory, decline as the straw decomposes.
> Carbon
> concentrations were compared with new straw from 2008 grown and dried at
> our
> research center.  As expected, the straw from around sensors with a
> history of
> high relative humidity had the lowest carbon concentrations.
>               For those who know more about this then I, is total
> carbon a good measure of straw decomposition?  What other tests could be
> done
> to determine the extent of straw decomposition without samples of the
> original
> straw at the time of baling or building?  I was considering comparing
> stable
> carbon isotopes C12 and C14.
> 3.           I’d like to submit a paper to the Journal of Asian
> Architecture and Building Engineering, a peer reviewed Journal sponsored
> by the
> architectural associations of Japan, China, and Korea, by April 8 for
> publication in November.  Would anyone be interested in helping me with a
> statistical analysis of the carbon experiment described above?  Last year 
> I
> received help with a paper from a couple of people on this list.  Many
> thanks.
> Kindest regards,
> Kyle Holzhueter
> Nihon University
> Graduate School of Bioresource Sciences
> Architecture and Regional Ecological Design Studio
> 1866 Kameino Fujisawa-City Kanagawa-Prefecture 252-8510
> TEL/FAX (81)466-84-3364
> http://hp.brs.nihon-u.ac.jp/~areds/
> http://www.cnes.brs.nihon-u.ac.jp/
> ============= End of Forwarded Material ============
> -- 
> === * ===
> Rob Tom
> Kanata, Ontario, Canada
> < A r c h i L o g i c  at  ChaffY a h o o  dot  C a >
> (manually winnow the chaff from my edress in your reply)
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