[Strawbale] Fw: [FWD] rainscreens, straw decay

[Brian Waite]

Ref. rainscreens/tolerable moisture levels. Very useful website below Brian

http://www.buildingscience.com/documents/digests/bsd-112-building-science-for-strawbale-buildings/?full_view=1



> 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
>> JAPAN
>>
>>
>> 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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>