How to Repoint a Foundation

Remove old mortar from the joints. Chip it away with a hammer and chisel. If you have a lot of mortar to remove, use an angle grinder with a diamond blade. Cut through the old mortar to a depth of one inch. Run the blade through the middle of the mortar joint, not along the brick or cement block, so you don’t damage the masonry.

Use a whisk broom to brush out any debris that remains after you run the angle grinder and chisel over the joints. If you can’t reach loose debris with the broom, use compressed air from an air compressor to blow it out.

Mix a small batch of mortar mix until it’s the consistency of peanut butter. The mortar should stay on the trowel when you turn the trowel upside down.

Work the mortar mix into the joint with a trowel. Avoid getting mortar on the face of the foundation. If the joint is deep, fill it half full with mortar. Wait until the mortar dries enough so you can see a thumbprint impression on the mortar, and then finish filling the joint.

Smooth a jointing tool over the surface of the repointing to make it look like the original joint. For best results, finish vertical joints before doing horizontal ones.