Masonry waterproofing requires a careful selection of materials and application. Waterproofing products can range from surface coatings to cementitious lining systems. Waterproofing products protect brick from weather damage and prevent structural dampness. Before choosing a product, determine the source of dampness in your walls. This may include a structural problem or a simple leak in a wall assembly.

Sealers

The best masonry waterproofing products protect brick and stone from moisture damage. They also guard against mold, mildew, and efflorescence and improve color retention. These coatings are typically straightforward and may be applied with a brush, roller, or spray equipment. Surface repellents are designed to coat the pores of concrete masonry units (CMUs).

They protect against rainwater penetration when applied over porous masonry surfaces and reduce dirt accumulation and staining. A liquid-applied membrane binds to the substrate and can stretch as the foundation settles, providing elongation to bridge small hairline settlement cracks in masonry walls. They are suitable for below-ground applications that experience ponding water, such as cove joints.

Liquid membranes are also a good option for above-ground applications subject to hydrostatic pressure. This includes sidewalks, driveways and parking areas, adobe or clay brick chimneys, and mortar and retaining walls. They also seal against deep water penetration, freeze-thaw, and deicing chemicals and control concrete dusting and efflorescence.

Paints

Choosing a paint specifically designed for masonry is essential if you’re considering painting a brick surface. It should provide a thick sealant to withstand harsh weather and extreme temperatures. It should also be breathable to prevent moisture from building on the surface, causing cracks or mold.

These coatings can be applied to dry or slightly damp substrates and have various color choices, hiding characteristics, and durability. They are generally inexpensive, have good alkali resistance, and provide a water-resistant surface. Typically, these coatings can be used to repair existing masonry structures.

Adhesives

Unlike sealers, which do not form a barrier against water, waterproofing products with repellents penetrate the cracks and nooks of your masonry. This allows trapped water to evaporate while keeping your masonry gas permeable, and using a masonry construction adhesive with a repellent to protect your chimney is vital.

Masonry adhesive is preferable to mortar for small jobs that do not require a lot of structure, such as replacing a single brick or repairing a cracked veneer. Most masonry construction adhesives are easy to use without mixing or troweling. They come in cartridges easily attached to a caulking gun, simplifying the application process.

Repair Materials

Brick, concrete, and masonry are naturally porous, and unless an integral water repellent is used to make the bricks or mortar, they need regular waterproofing. A simple test, splashing water on a surface, can reveal whether it needs protection.

If the surface rapidly becomes darker and absorbs more water, or if it develops a white powdery residue called efflorescence, it needs a waterproofing application. The most critical factor in a successful old masonry repair is the thoughtful selection of the correct repair material. The materials used should have similar elastic modulus, thermal expansion characteristics, and bond strength to the existing masonry.