How to Fix a Stone Foundation

Stone foundations are common in older homes and add a touch rarely seen in modern home designs. While these old stone foundations are attractive, many have aged to the point that they require repair to continue functioning well as a structural support. Loose stones and cracking mortar joints can create damaged areas, which if not repaired can extend further into the foundation, causing even more damage. By catching the damage early, it's possible for you to fix your stone foundation, returning strength to the foundation and extending the life of well-constructed older buildings.

Things You'll Need

• Gloves
• Wire brush
• Chisel
• Mortar
• Bucket
• Trowel
• Concrete sealant

Instructions

1. Examine the foundation for damaged areas. Early damage that you can fix yourself in a stone foundation includes loose, missing, or broken stones and cracked mortar.

2. Remove any loose stones from the foundation and set them aside near the hole they were removed from. Work gloves should be worn throughout the entire repair project. Clean the holes left in the mortar from the loose or missing stones. Use a wire brush to remove any dirt or debris that may be present and then wash the holes with clean water. Clean the loose stones of dirt and debris, as well. If the mortar was cracked in the holes containing loose or missing stones, remove the cracked mortar with a chisel.

3. Mix the mortar according to the manufacturer's instructions in a large bucket and place the mortar into the holes left by the removed stones, lining the walls of the holes. Butter the stones with the mortar by applying a layer of mortar to the end of the stones themselves and then push the stones back into their respective holes. Use the trowel to remove any excess mortar.

4. Place mortar into the holes left by missing stones. Completely fill the holes with the mortar and then smooth the edge of the hole using the flat edge of the trowel. Allow the mortar to set for three days.

5. Repeat the process of searching for and reapplying mortar to loose or missing stones for the interior of the stone foundation accessible in your home's basement.

6. Repair any areas containing cracked mortar. Chisel out the crack to level the sides and even the depth to about a half-inch, and then fill in the cracks with fresh mortar. Allow all repairs three weeks for the mortar to cure.

7. Cover the stone foundation with a layer of cement sealant to protect the new mortar repairs.

Tips & Warnings

• Keep new mortar surfaces damp for three to four days to prevent cracking as it dries.

References

• Ask the Builder: Home Repair Foundation
• Trained Eye Home Inspection: Mortar Repair in Stone Foundation
• eFoundationrepair.com: Causes of Stone Foundation Cracks

Resources

• Inspectapedia: Foundation Inspection