I have 1880 house with stone foundation that is cracking/crumbling and needs to be repaired. We are getting different opinions about what it needs and technique used.

One guy wants to chisel/then power wash the mortar out , repoint and then skim coat 2 layers of lime wash to "waterproof" (parge) But it would cover up the stones.

Another guy says you don't need to parge the walls with skim coat and he would repoint with deep penetration of mortar, more mortar to really fill space.

What is real story as far as what old foundations need for repair. I feel like I'm being sold a used car sometimes.

Anyone know of a legit, trustworthy company that knows what they're doing in the Boston, MA area?

Thank you!