Repairing old masonry is not done according to the same principles as concrete repair. Brick, stone, adobe, and lime-based structures are made from materials with different chemical compositions, elasticity, and vapor permeability — the repair material used must be compatible with the original material. One of the most common mistakes in renovation work is pressing cement mortar into old lime-based masonry.
If the repair material is harder than the surrounding masonry, stress concentrates in the weaker material — the original masonry — causing it to crack. This is especially true for old brick and stone masonry, where the original mortar is lime-based and soft, making modern Portland cement-based repair mortar incompatible.
NHL lime-based repair mortar is a natural hydraulic lime-based, breathable, vapor-permeable, and compatible material for brick, stone, and adobe masonry. For historic buildings and heritage masonry, this is the only suitable repair material — WTA-compatible. Cement-based masonry repair is suitable for modern brick and block masonry where the original material is also cement-based. Repairing adobe structures should only be done with adobe- or clay-based materials: cement-based repair materials pressed into adobe will detach over time due to moisture movement in the adobe.
For cracks, the width and depth of the crack determine the repair method. Hairline cracks can be treated with surface material; structural cracks must be stabilized by injection. For stone spalling and material loss, cleaning the damaged area and regularly applying a primer and repair mortar compatible with the original material is necessary. For missing joints, removing old, crumbling joints and repointing with compatible material is critical — especially for outdoor stone and brick masonry, where the joint is the primary barrier against water penetration.
Browse our masonry repair materials or request advice to assemble a compatible repair system suited to the type and age of your masonry.
The Kerakoll Color Collection is an integrated project that includes innovative materials - resin, cement, handcrafted wood, microcoatings, paints, and glazes - coordinated on a single color palette.
