Old barns with stone walls are built to last. Many have been around for over a century, carefully preserved and maintained while still seeing everyday use. While the stone foundation walls of these old barns can remain structurally sound for over a hundred years, that’s only possible through proper wall repair as soon as damage occurs. Loose stones or cracking mortar are two common occurrences that can quickly lead to major structural damage if not caught early. Making the early repairs, however, helps to ensure the longevity of a stone barn, creating a structure enjoyed through multiple generations.
Examine the wall, looking for any damaged areas. Pay careful attention to any loose or missing stones, broken stones or cracks in the mortar holding the stones together.
Remove loose stones from the walls and place them at the foot of the wall beneath the hole created by their removal. If the stone is only partially loosened in its place then use a prybar to remove the stone, taking care not to damage adjacent stones. Place the tip of the prybar beneath the loose end of the stone and apply pressure to the stone as you work the prybar to the stone’s rear, popping it out of its wall placement.
Remove dirt and debris from the holes created by removed or missing stones. Use a wire brush to scrub away the dirt and then wash out the depressions with clean water. Clean any stones removed.
Clear away cracked mortar in the holes using a hammer and chisel. Place the point of the chisel against the cracked mortar at the cracked area and hit the head of the chisel sharply with the hammer to widen the crack and break off the chipped material. Remove the material from the wall and scrub away loose mortar with the wire brush.
Mix a batch of mortar in a bucket following the manufacturer's instructions. Add enough water to give the mortar the consistency of peanut butter. Use a trowel to press the mortar into the depressions left by the stones you’ve removed.
Cover the walls of the depression with the mortar, matching the depth of the mortar with the mortar seams holding surrounding stones in the wall. Place a layer of mortar onto the end of the stone removed from the hole.
Place the mortared end of the stone into the hole, pressing it firmly into the hole until it sits securely. Remove any excess mortar that flows out of the hole with the trowel as you push the stone into place.
Replace spaces left in the wall by missing stones by filling them with mortar, levelling off the mortar to match the level of joint lines between stones with the flat of your trowel.
Remove cracked mortar from the walls using the hammer and chisel. Clear away loose mortar with the wire brush and then replace the mortar from the freshly made batch. Level the replacement lines of mortar with the surrounding existing mortared joints using the rounded end of a wooden dowel. Allow three weeks for all to cure completely.
Spray a layer of concrete sealant onto the walls of the barn to protect the repairs from damage. The sealant should dry in 48 hours.
Rather than fill empty wall spaces with mortar, locate matching stonework and install the new stone instead.
Wear work gloves and safety goggles throughout the repair process.