Hydraulic pressure caused by water resting against a stone foundation wall will eventually push against the stones and cause them to move. When a stone shifts, the mortar around it will crack and deteriorate. Crumbling mortar allows water from rain and melting snow to seep into your home and flood your basement. You need to shift the stone back into position and replace the mortar to stop the flooding. Here is how you can shift a stone back into position and replace the old mortar around it.
- Mortar Mix
- Trowel
- Plastic Pail
- Water
- Mini-Excavator
- Masonry Hammer
Step One: Dig a Trench
You need to dig down on the outside of the foundation wall until you reach the exterior side of the stone that has shifted. Remove enough dirt so you have enough room to safely work in the trench you have dug.
If you had to dig a deep trench to reach the shifted stone, you should use wall bracing to prevent the dirt from collapsing back into the trench.
You can use plywood and 2" x 4" boards to build a wall trench. Place the plywood boards against a section of the stone wall that is in good shape, and place another board on the other side of the trench so it rests against the dirt wall.
Place 2" x 4" boards between the two the walls to form an "H" brace.
Step Two: Remove the Old Mortar
Break away the surface mortar around the stone with a masonry hammer on the exterior and interior side of the stone. You only need to chip away the first two or three inches of mortar around the stone. Remove the broken pieces of mortar and whisk the area clean with a hard-bristled paint brush.
Move the stone to position it back in place. You can move the stone by gently tapping it with the masonry hammer until it is positioned correctly.
Step Three: Put in New Mortar around Stone
Mix the mortar and water together in a plastic five gallon pail. You need to push the mortar into the crevices to fill them up with mortar.
The easiest way to do this is to put the mortar on the underside of a trowel, and then push the mortar off the trowel with a pointing tool into the crevices you cleaned out. Allow the mortar to dry. Drying time varies by the type of mortar. Check the directions on the packaging for the actual drying time of the mortar you used.
Step Four: Fill in Trench
Remove the wood from the trench and back fill it with the dirt you originally removed from it.
Contact a foundation crack repair professional if you need expert help.
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