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

[Michael lough]

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
>>
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