repointing

Repointing is the repair of deteriorated mortar joints in brick, stone, or other masonry walls. The goal is to restore structural integrity, improve weather resistance, and reduce water intrusion that can lead to damage to the masonry units.

The process typically involves removing the damaged mortar to a depth that reaches sound material, then raking and cleaning the joint before applying new mortar that matches the original composition and finish. In historic work, lime-based mortars are commonly used; modern walls may use cement-lime or cementitious mortars that are compatible with the substrate.

Materials and joint profiles vary by building type. Lime mortars are breathable and flexible, suitable for older bricks and stone; cement-based mortars cure harder and can trap moisture if used on unsuitable substrates. The color and texture of the new mortar should blend with the surrounding fabric, or be historically appropriate in restoration work.

Tools and methods. Removal can be done by hand with chisels and putty knives or by mechanical tools, depending on the masonry. The joints are dampened before tooling to reduce dust and help adhesion. The new mortar is compacted with a pointing trowel and finished to match the joint style, such as recessed, flush, or weathered joints. Joints are kept rounded to shed water.

Considerations. Repointing can be disruptive and exposes interior spaces to weather during work. It should be done by qualified masons, especially on historic structures where the wrong mortar or too-rapid curing can cause damage to bricks or stone. Work is usually timed for dry, mild weather, and curing conditions are managed to avoid rapid drying or freezing.

Maintenance. Regular inspection of joints, cleaning of dirt and biological growth, and re-pointing as needed help preserve masonry. Avoid non-breathable sealants that trap moisture; breathable finishes and proper drainage are preferred.