Interior stone wall - crumbling!

[Tonyb]

I've just finished the main renovation on a village house in the Herault (dept. 34).

The ground floor used to be the 'cave' of the house and was converted by the previous owner into a bedroom. One of the walls is exposed stone and it curves in an arch to become the ceiling. The wall is an outer wall, so the outside of the house is on the other side. 

The problem is that the stone and the pointing/cement on the interior wall is very soft and crumbly and obviously needs urgent attention. On certain parts of the wall there are deposits of salt, which points to a long term damp problem. I had the house surveyed before I bought it and the surveyor pointed out this problem. He said the exterior walls were fine and the house was structurally sound (phew!).

My artisans say that the damp is not rising damp, but has come from years of neglect where the house has leaked from the top down (poor weather proofing on the terraces) so that water has collected on the ground floor and the walls have been permanently wet. Now that the house has been sealed and dried out the delicate state of this wall is apparent.

They say that the wall/ceiling can be refurbished but it is outside their expertise. From what I understand, renovating stone walls is a time consuming activity, which makes it rather expensive! The artisans are asking a friend of theirs if he can help. He's an enthusiast for stone walls and renovates them as a hobby. He'll do it for liquid cash, which is nice!

I just wondered if anyone has any experience or advice on this subject? Can anyone recommend a stone wall expert in the Herault area?

I suppose one solution would be to simply concrete over the stone and then paint over, but I'd rather preserve the exposed stone if I can.

Thanks in advance.

Tony

PS I'm posting this on the Living France forum, The Languedoc Page and the 'Brits in Beziers' msn group, therefore sorry for any duplication!