[Strawbale] Re: Lime rendering and the big freeze

[Michael K Lough <mkl18@pobox...>]

In my admittedly limited experience I have found a few things to be 
probably true.

Lime/sand only plaster is best with dry sand. I use a poly fibre 
additive bought from a local Ready Mix  plant in lieu of horse hair 
or similar. I think it works well although I do get some cracking.

My first experience with Lime render/plaster tells me to expect 
cracking to some extent..This is easily dealt with in a Limewash 
later on.

Drying varies with temperature but if the render is really pushed on 
it does stick well without the need for plastic mesh or clay slip or 
earthen first coat. The first year I managed to get about 15 percent 
done before I had to abandon the site due to cold and snow. So it was 
a sort of experiment .I discovered that tarping the bales was not 
necessary as snow did not penetrate them and even horizontal rain 
only went in a few inches and dried fairly quickly when the rain 
stopped.
The bales 6 months later were still as good as I left them, maybe a 
bit blonder due to UV but thats was it. I was of course worried about 
this and did visit during February when the snow was up the sides in 
drifts to about 4 feet, but it was all fine, the plaster was cracked 
here and there but still on and holding well.

I understand a long drying time is a good thing and a moist climate 
is better than a dry one for curing Lime render. I am not sure of 
this but there is some theory that freezing does not affect Lime 
curing (which I agree does seems counter intuitive) but what I've 
heard is that it might actually make it better.
I have had some putty soaking for three years now and it has frozen 
twice and is even if a bit stiffer to mix "stickier" after mixing 
than 45 day old putty. So I might be able to see that adding just 
sand would not change this  process  and that if Lime plaster is self 
healing then the water component in it getting hard might not 
permanently damage the plaster through expansion but really all I can 
say  for sure is that I have a plastered wall which has absorbed 
water due to rain and then frozen and it did not fall off and the few 
cracks were then "washed out" or is that "washed in"?

I hope this helps someone

Michael