On Thu, 17 Jun 2010 12:10:06 +0100, george [dicegeorge] wrote:

If you're using portland cement and stone then its non porous so why
have a breathable paint?

The stone is sandstone not granite, so is a little porous. Over time
water will get bhind the paint layer I'd rather it had some chance of
getting out rather than sitting there and either making it's way
inside or freezing damaging the stone or paint layer. We had some
quite long periods (weeks) of consecuative "ice days" last winter.
Days when the air temp didn't get above freezing and overnight mins
of -10C.

One reason for lime mortar is that it's softer than stone, so if the
building settles then the pointing gives way, rather than the stone
cracking.

This building has probably first built about 300 years ago, don't
know if it has been rebuilt since. Apparently it was a delerict shell
30 or 40 years ago. It's not likely to be still settling, it's almost
certainly built directly onto the bedrock as well.

--
Cheers
Dave.