I HATE rock foundations. I have three buildings with them and they are a maintenance nightmare. I am in New England and we keep having to replace sections due to frost action. Also, they need repointing. And they leak. And they are drafty. Never again am I buying a building with a rock foundation without the budget to just replace the #&$@ thing! Anyway, good luck. That actually looks to be in pretty good condition.

But you should get that vine out of there. It can get in the joints and speed up the deterioration.

Thanks for the reply! That was why I was thinking about cover the stone and (mortar pointing) with a layer of cement or concrete.

I did spend $1000 to have the inside spray foamed to below grade and it paid for itself in one year. But the constant headaches, maintenance, and frost movement I would not willingly deal with again. I have another corner that needs replacement because there is enough movement that we wonder if the door will open close during January and February.

I once read that a stone wall is only as good as the man who laid it. The mortar doesn't really do much other than fill in the gaps. I must be lucky and have one built by a talented mason. My house is still square and level in all rooms.

In order to make stones stay longer, should I put a layer of cement outside the stones? Or just re-point them when the mortar is loose? I think if I put a layer of cement above the stones and mortar, it will protect the stones better, but i will not able to see the stones in the future because they are covered by cement, and i don't know the real situation of the stones either.

Just my opinion because I am looking at a house with stone and dad was a mason. I would repoint only unless the look of stone isn’t your taste.

As long as the joints are maintained and water is diverted from the wall its best to avoid parging and pay attention to the interior of the stone wall. That's not usually a DIY project. Most of my renovation projects have had stone foundations and the best contractor I've found in New England is Done Right Services. Stabilization of the interior will prevent the exterior from moving and losing mortar.