[Greenbuilding] Chickens, Roosters, plaster, lath and you (or something like that)

[Rob Tom]

Sorry that I can't quote the messages because they got deleted before  
downloading mail the AM but I'm pretty sure that it was Aallaan (there's a  
B and an R in there somewhere too)who was talking about chicken wire,  
plaster,water intrusion and corrosion.

In strawbale construction, there was some proof of concept testing that  
was done during the previous millennium to demonstrate the efficacy of  
pre-tensioning the plastering lath in order to precompress the bale walls,  
resulting in increased lateral stability etc..

IIRC even wimpy 22 gauge chicken wire produced impressive results. I dont  
know what Murrican chicken wire is like but up here in MooseLand, even the  
wimpy 22 gauge stuff is hot-dipped galavanised. I have some out in the  
yard that's been exposed to weather for at least 15 years or more and it's  
not showing any signs of corrosion yet.

But WRT plaster & water intrusion ... there not need be any cracks in  
order for the corrosion of the lath to occur.

Plaster and the clear cover over any embedded metal is usually so thin  
that it provides negligible protection against corrosion.  Plaster (even  
Portland cement plaster) should ideally be protected by overhangs so that  
rain-soaking is minimised and it should also be detailed so that if  
wetting does occur, it can drain and dry in an expedient manner.

It might be worth mentioning that in strawbale construction, the SmartOnes  
use plastic mesh (ie Tenax (TM)) these days, rather than steel for the  
plastering lath/tensile anchorage systems. One has the choice of  
polyethylene, polypropylene or nylon fibre. The first two may be subject  
to stress relaxation. The last of course, goes "B-O-I-I-I-INNNNGG !".

Oh, yeah. Tadelakt.

If you look in on the archives of the SB-r-us Yahoogroups strawbale list  
and plug "Tadelakt" into the search facility there, you'll find some  
postings by Bill and Athena Steen and others.

I recall Beel mentioning that it takes something like 4 hours to do a 1  
metre square section of wall, if the Tadelakt is to be done well.

     http://groups.yahoo.com/group/SB-r-us/message/8369


-- 
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Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at   C h a f f Y a h o o  dot  C a  >
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