Old stone walls

[GoodIntentions]

Bought an old property a couple of years ago and have been working hard to improve the structural stability of the internal stone walls (many of which looked more like dry stone walling as the original mortar has entirely dropped out.)

Under advice from a more experienced family member, I have cleaned and scraped back the stone, removed old crumbling mortar, and replaced with lime mortar. The walls suffer with some damp issues throughout, with the root cause likely now solved. The mortar repair on the walls has been extensive, in some places to depths of around 18".

The problem is that we used PVA watered down (roughly 1:10 mix with water) to dampen the clean surfaces and reset the stones, and have just discovered that PVA in the context of lime plaster on lime mortar is a huge no-no. The research suggests two problems:

1) PVA being non-breathable
2) emulsification of PVA over long term breaking down adhesion

Problem one won't apply as the lime mortar doesn't contain PVA and it can breathe between the rocks without issue, however, problem two is our main concern.

Anyone got any advice on how to fix this problem, if it is indeed a problem? Does anyone have any experience of this; what are the long term consequences if we do nothing (assuming a correct/normal application of thermal lime-based plaster on top)?

Thanks in advance for any advice on solving this!

 

[Wayners]

Bit late now.
Probably have to wait and let it degrade and the next person will do it again.
Only way to fix would be to dig out and wire brush off pva.

 

[GoodIntentions]

Any idea how long that might be? Are we talking a couple of years or a couple of decades?

 

[Lower]

I suspect that it'll probably be fine. There should be enough friction between the rough stones and the mortar for it to grip, even if the pva prevents the lime bonding properly.

Have you tried removing a section of your lime mortar to see how well its bonded? I think that will give you your answer.