Step 2 assess the damage.
How to repair stone foundation walls.
In order to repair your stone foundation you need to tackle the problem from the both inside and the outside of your home.
Although they can look very attractive the mortar joints are prone to weakening or cracking over time.
Afterward a good masonry sealer will protect them against moisture and damage.
Stone foundation walls are common on many older homes.
Modern concrete foundations have helped minimize problems with foundations but if you live in a home that 100 years old or older you could have a stone foundation.
Use your shovel to dig a 1 foot deep trench along the perimeter of the stone foundation.
Start with the exterior.
Sometimes all it takes is a thorough cleaning to help your stone basement walls look almost new again.
If a space between foundation stones is wider than 3 inches or so fill it with mortar and then press a small rock firmly into the mortar to fill the space.
Your problem is most likely that stones have come loose and shifted out of place.
While concrete is poured in a single batch to create a solid foundation or basement wall you can see that this is not the case with stone.
Eventually you can be left with loose and missing stones or bulging and collapsing foundation walls.
Pack more mortar around the stone.
Pour an interior wall.
A professional foundation crew will construct a one sided concrete form inside the old basement perimeter and pour a new concrete wall.