No amount of material applied to the inside of a stone wall will prevent the wall from seeping or leaking- in fact, you will cause more problems, because if water gets in the wall, it has to get out. Stone or brick, even concrete- nothing can hold water once it is in.
So, if you can’t dig up around your whole house and waterproof the outside (and there is some doubt if that’s even feasible on a rough stone wall) you need to allow the stone to leak the water out- into your basement! Obviously, that could cause problems- so here’s the trick:
The best solution to this is to allow the water to run down the wall and into the pea gravel trench that runs around the wall to the sump pump. (yes, the sump and drainage system is required) There are several products out there which have small channels which face up to the stone, and prevent the concrete from completely sealing the route to the drainage system.
I’ve used a plastic “molding” that sits right at the stone wall, from above the concrete to the pea gravel. There is also a “membrane” which isn’t adhered to the wall as implied by the name, but acts as a flashing, resting inside a true membrane which is under the slab and must come up 6″ or so above the concrete floor on all sides, which assures the water goes to the drainage system. Check online or talk to your concrete contractor to see what they prefer using, but make sure that you understand the mechanics of it.
This isn’t rocket science, but requires attention to detail, so supervise your concrete installation closely! Whoever you have doing this work, make sure they comprehend both how to install the product and the gravity of this detail to making your old house stay dry. Then, supervise the installation anyway. This is a make-or-break detail.
