Hello Tomas!
Maybe too late for
you, but you asked
about recipe for lime plaster outside.
I am not sure for
strawbale walls, but for
stone walls (I hope it’s the same) restorers use ratio 1
: 1, what mean
that 50% sand and 50% lime.
Now days
surrounding air have a lot pollutants
and pure lime plaster is not so strong enough for active
components in outside.
In this case is permissible today to add very small
amount cement too; for strengthening
plaster.
Regards,
Enn
Veesalu
Last week put some scratch coat onto my
strawbale garage. The render
mix that I have used for the inside was 4
parts coarse sand to 1
part pure clay to 0,5 part chopped straw. With this
mix everything
went perfect, no cracks appeared when the plaster
dried.
For the outside scratch coat I used the
same ratio plus
added hydrated lime in powder to the mix. The ratio
of the lime I tried to
keep to around 5% of the mix. The outside plaster
cracked a lot. I'm
sure that the reason for the cracks was lime. There
was little area
outside where I did not put lime in the plaster, and
in this area no
cracks appeared when the plaster dried. What ratio
of lime should I keep in the
mix for the outside?