[Strawbale] re RE: The BIG question (Michael Lough)

Mon May 15 20:08:32 CEST 2006

Hi Michael,

Im not sure what type of cladding was used or how. I am familiar with rain 
screens, I used to work for a Dutch company  installing curtain walling and 
rain screens on buildings  at airports in the UK.   We didnt clad any 
organic materials though, only steel and concrete will plenty of drips and 
rain channels.
I dont have further info at hand but I can ahve a look around to see if I 
can find anything.

  "Eric Larmett" <Eric.Larmett at arup...>
>Reply-To: European strawbale building discussions 
><strawbale at amper....muni.cz>
>To: "European strawbale building discussions" <strawbale at amper....muni.cz>
>Subject: RE: [Strawbale] re RE: The BIG question (Michael Lough)
>Date: Mon, 15 May 2006 17:18:22 +0100
>
>Paul
>
>The concept of interstitial condensation is well known. This is likely
>to occur when the outer face is sealed. However in recent times the
>construction industry has been using the concept of rain screen
>cladding, that is, the cladding acts almost like a vertical umbrella,
>allowing air movement behind the cladding but shielding the structure
>from rain.
>
>I assume the metal cladding you refer to was effectively sealed.
>
>Do you have any further info?
>
>Regards
>
>
>Eric Larmett
>Senior Engineer
>
>Arup Building Engineering
>St James's Building, Oxford Street, Manchester M1 6EL
>tel:           +44(0) 161 228 2331
>fax:          +44(0) 161 236 1057
>mob:       +44(0) 7855 366510
>internal:   63382
>eric.larmett at arup...
>www.arup.com
>-----Original Message-----
>From: strawbale-bounces at amper....muni.cz
>[mailto:strawbale-bounces at amper....muni.cz] On Behalf Of paul sheraton
>Sent: 12 May 2006 18:29
>To: strawbale at amper....muni.cz
>Subject: RE: [Strawbale] re RE: The BIG question (Michael Lough)
>
>
>Hi Michael
>
>thanks for your reply.
>
>By coincidence I found  a link this to a pilot study from Canada which
>highlights my basic concern expressed in my original post, you might be
>interested.
>
>
>Pilot Study of Moisture Control in Stuccoed Straw Bale Walls | CMHC
>http://www.cmhc-schl.gc.ca/en/inpr/bude/heho/heho_004.cfm
>
>
>
>Its a study of cement stucco finished straw bale walls and the possible
>negative effects this could have in trapping moisture in the wall,
>promoting
>problems with damp.
>
>My concern is that in colder climates clients/homebuilders go for
>"security"
>and put on a cement render for protection against the elements when its
>possible this might cause problems in the future. I would be genuinly
>interested to know what percentage of reported failures of straw bale
>structures were cement stuccoed.
>
>There is a classic case froma few years back in the UK. A couple built a
>
>straw bale house which was followed on a programme on  national TV. The
>architect decided the prudent approach was to cover the outside in
>weather
>proof cladding, metal cladding. Interstitial condensation and the straw
>started to rot. The cladding was replaced but of course most people just
>
>remember the straw  rotting unfortunately
>
>abientot
>Paul
>
>
> >From: "Michael lough" <michaelklough at sympatico...>
> >Reply-To: mkl18 at pobox...,        European strawbale building
> >discussions<strawbale at amper....muni.cz>
> >To: strawbale at amper....muni.cz
> >Subject: [Strawbale] re RE: The BIG question (Michael Lough)
> >Date: Thu, 11 May 2006 13:40:35 +0000
> >
> >
> >
> >
> >
> >
> >Hi Michael,
> >
> >The original qoute I responded to said failures reported in NE America.
>I
> >didnt say all buildings in America were ciment rendered
> >
> >sorry my misunderstanding...
> >
> >
> >
> >
> >
> >
> >just my observation that  quite a few have been, especially in cold
>snowy
> >areas like the NE.
> >
> >well Canada qualifies I think in this regard and Portland/Lime mixes
>are
> >considered acceptable here by a few. The issue seems to be whether or
>not
> >testing was done on the long term effects of using a non permeable
>material
> >in sufficiently high quantities in a bale render allowing for
>convection
> >currents within the bale wall assembly itself. I havn't seen anything
>on
> >this here and have only read of experiments in Europe.
> >
> >
> >
> >
> >
> >A stucco plaster is called stucco
> >
> >Thanks for this. I have been labouring under a misunderstanding. A
>quick
> >check proves you are in fact correct.
> >
> >I thought for a while that I should crusade on behalf of the word
>cement as
> >it seems it is a word that has come to mean Portland cement whereas it
>was
> >originally meant to mean something more broad as in cementitious but
> >realised the futility of it eventually .
> >
> >
> >
> >
> >I understand that in drier areas like Arazona, clay or lime based
>plasters
> >are used, in colder, wetter areas ciment/lime finishs are more ususally
>
> >used.
> >
> >Not sure if it is quite that cut and dry not having the figures
> >
> >
> >
> >
> >It is a shame that there does aopear to be a tendancy to try and ignore
>
> >problems/failures in in case the "cause" is damaged. I think there is a
>
> >tendency to panic at the eleventh hour and put on a ciment based
>finish.
> >
> >It is a difficult question and perhaps there is no easy answer. If one
> >wished to why not build for a short building lifetime with recyclable
> >materials? If the walls rot take the house to pieces and build again.
> >perhaps the idea of "permanence" established in European culture as a
> >desirable necessary quality for a building is less developed in North
> >America where hunter gatherers lived in animal hide mobile structures
>not
> >so long ago. The advantage of using lime/sand only can perhaps only be
> >realised (or not) through experience and the only true test, that of
>time
> >perhaps.
> >
> >
> >adios
> >
> >Michael
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >>
> >>Hi Michael,
> >>
> >>The original qoute I responded to said failures reported in NE
>America. I
> >>didnt say all buildings in America were ciment rendered, just my
> >>observation that  quite a few have been, especially in cold snowy
>areas
> >>like the NE.
> >>
> >>A stucco plaster is called stucco because it contains either lime sand
>mix
> >>which is the original method or the modern ciment/sand mix, in the UK
> >>called a render. Gypsum based plasters are called plasters not stucco.
> >>"
> >>I understand that in drier areas like Arazona, clay or lime based
>plasters
> >>are used, in colder, wetter areas ciment/lime finishs are more
>ususally
> >>used.
> >>
> >>It is a shame that there does aopear to be a tendancy to try and
>ignore
> >>problems/failures in in case the "cause" is damaged. I think there is
>a
> >>tendency to panic at the eleventh hour and put on a ciment based
>finish.
> >>
> >>>From: "Michael lough" <michaelklough at sympatico...>
> >>>Reply-To: mkl18 at pobox...,        European strawbale building
> >>>discussions<strawbale at amper....muni.cz>
> >>>To: strawbale at amper....muni.cz
> >>>Subject: [Strawbale] the BIG question
> >>>Date: Wed, 10 May 2006 04:48:42 +0000
> >>>
> >>>sorry for lateness in replying but have been distracted recently...
> >>>
> >>>"There have been reports of "failed" straw walls in NE America with
>some
> >>>admitting the damage was likely  caused by dampness but no  admission
>of
> >>>the dampness being caused by convection currents within a wall,
>therefore
> >>>no remediation has been undertaken as it has not been proved. Which
>of
> >>>course means here  "business as usual"
> >>>
> >>>
> >>>+++I wonder how many of these failed walls were plastered with a
>cement
> >>>based render/stucco?
> >>>I know the Americans like their straw bale buildings cement stuccoed.
> >>>
> >>>
> >>>A generalisation I'm afraid. It is true that Portland/Lime mixes are
>used
> >>>and one Strawbale commercial group in Canada has even accepted web
> >>>"sponsorship" from a Portland cement manufacturer but Portland use in
>
> >>>plaster is not the case all over North America. In the US there are
>quite
> >>>a lot of Lime/sand plastered structures I believe. The  heritage of
>straw
> >>>bale appears to me at least to be more Arts/craft conscious less
> >>>"industrial" than in Canada.
> >>>
> >>>The issue of Portland containing plasters (not stucco, that is gypsum
>
> >>>based I believe) and the effect it may create once on straw over time
>in
> >>>a humid region is one I am not that informed on. But it appears that
>the
> >>>test of time is underway. One hears of problems and discussion and
>then
> >>>nothing...No resolution, no rockingthe boat. Time perhaps
>unfortunately
> >>>will tell...But then again I may be "outside" the truth. There is
>doubt
> >>>here in quiet corners.
> >>>
> >>>The real problem is the cost of real industrial testing of straw
>bales.
> >>>
> >>>
> >>>
> >>>
> >>>++I think if you are going to use an organic material in a buildings
> >>>structure, provision for air movement  through that structure becomes
>
> >>>paramount, even at the loss of thermal performance.
> >>>
> >>>It depends on the amount of the moisture in the air and at what point
>
> >>>does this warmed moist air come into contact with outside conditions
> >>>which will then turn the moisture back into water? This is the
>question.
> >>>The dew point can move with the seasons also.
> >>>
> >>>What could happen if say heat went into plaster from the inside which
>
> >>>warms the air immediately inside the bale Will this heat rise through
>the
> >>>bale(s) If there is air inside the  bales why wouldnt it? And would
>this
> >>>air form a convection current inside the bales albeit a slow one. If
>the
> >>>outside is cold then the warm air would meet  the colder outer bale
> >>>inside surface at some point and  condensation would result ...?
>Would
> >>>Portland allow for "expiration"? Doubtful as it is used for swimming
> >>>pools...
> >>>
> >>>
> >>>
> >>>
> >>>++"sealing" in a straw bale wall with cement plaster seams like
>asking
> >>>for trouble unless it is a dry climate.
> >>>
> >>>I share your instincts.Many others do as well. In Canada the
>potential
> >>>for problems is not seemingly acknowledged by everyone .
> >>>
> >>>
> >>>It would be interesting and very useful to have a reference to straw
>bale
> >>>wall "failures" to learn from, is anyone making a comprehensive
>record of
> >>>these situations?
> >>>
> >>>let it move, let it breathe!
> >>>
> >>>The single most important problem of building with straw bales is not
>the
> >>>subject of a permanent record. (not one that I have seen anyway)
> >>>
> >>>
> >>>It seems as though the collective attitude is to not give straw bale
> >>>construction a bad name while these problems are discussed quietly.
>The
> >>>trouble is that there are some perhaps less scrupulous individuals
>that
> >>>believe that no apparent discussion means no problems which means
>using
> >>>Portland is OK.
> >>>
> >>>its all a bit disturbing ...
> >>>
> >>>regards
> >>>
> >>>Michael
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >
> >
> >
> >____________________________________________________
> >    European strawbale building discussion list
> >
> >Send all messages to:
> >Strawbale at amper....muni.cz
> >
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> >
> >
>
>
>
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