Repairing stone masonry or starting over
A few loose stones or crumbling joints usually call for a repair, not a new wall. If it's mostly the mortar that's going, the fix looks a lot like brick pointing, just done in stone. The city's code exempts repairs that only swap in similar materials to maintain a wall, but an addition or a change in how it's built falls outside that, so a rebuild is a different talk with the city. When a wall is leaning or cracked clean through, I'll tell you a rebuild is the honest answer.

