5 Common Mistakes to Avoid When Waterproofing Masonry

Masonry and brick structures must be adequately waterproofed to prevent dampness, mildew, and fungus. These problems not only affect the appearance of masonry but can also cause structural damage to buildings. Incorporating a chemical damp proof course (DPC) into the structure helps to stop moisture penetration, thereby preventing problems like efflorescence, leaks, and corrosion. However, waterproofing masonry requires expertise and experience.

Not Knowing When the Water is Too Much

If water is allowed to collect in the cracks and pores of masonry, it can undergo a freeze/thaw cycle. When water freezes, it expands, forcing open the cracks that allow more moisture into the masonry walls and creating a cycle that continues to damage the brick and mortar. This process can also rust metal aspects of a fireplace and lead to deterioration in the chimney liner. It can also cause various other problems, such as stains on walls, mold and mildew in the home, and drywall cracks and crumbling. Masonry waterproofing can help protect your foundation from these issues. However, it is essential to ensure the surface of your masonry is dry before applying any waterproofing products. A wet surface affects how the paint binders cure and can lead to reduced performance.

Using the Wrong Mortar Mix

Masonry is beautiful and provides excellent structural integrity; however, masonry must be protected from moisture like most porous building materials. Without waterproofing, masonry can absorb water quickly, which will cause damage to the bricks and mortar. It’s true if your masonry is old. Using the wrong mortar type for repointing will cause moisture problems and structural damage over time. Most masons today use Portland cement to repoint old brick walls. While this is a good idea when working with new brick, it’s not recommended for repointing older brick or stone. The older brick and stone were designed to allow moisture to pass through the repointing mortar into the wall and evaporate naturally.

Using Too Much Water

Masonry walls need to be appropriately maintained & sealed to prevent water damage. With the correct damp-proofing products, such as Emperor Masonry Paint, this process can be much simpler & quicker than you might think. Brick masonry can be quite porous, meaning that it is easy for water to penetrate a wall. Over time, repeated hours of driving rains can cause a saturation point in the wall pores, which can lead to leaks & damage.

When this occurs, the wall can develop D-cracking or other internal damage, leading to crumbling. Water ingress also causes energy loss by reducing the thermal properties of the bricks. Waterproofing brick & masonry reduces this needless heat loss, saving homeowners money on their heating bills.

Covering the Membrane with a Thick Coat of Concrete or Mortar

Masonry structures comprise structural concrete masonry units (CMUs), which are characteristically porous. Load-bearing CMUs are designed to absorb 17 percent of their weight in water. Surface treatment repellents include water-repellent stains, silanes, and precise treatments such as acrylics. These treatments are primarily designed to cover the face of the masonry, bridging tiny cracks and voids. They also reduce vapor transmission and may intensify the substrate color. However, if the surface treatment layer is too thick, it can prevent sufficient flexural strength from being achieved. It’s essential in structures subject to deflection and loads above or below. In such cases, it is better to use an integral water repellent.

Not Maintaining the Masonry

Masonry does require regular maintenance and cleaning to keep it in good condition. Minor problems can be noticed with proper masonry maintenance until they become significant issues requiring expensive repairs or a complete facade restoration. Periodic cleanings should be made to remove stains, efflorescence, and graffiti. Using a non-aggressive cleaning agent, based on the manufacturer’s recommendations, is essential to avoid damage to the surface and surrounding materials. Control joints should be inspected for proper spacing and, if necessary, filled with backer rods and sealant. Periodic water intake tests can be conducted with Ryland or Karsten tube test kits to determine if the masonry is waterproof to 72 mph wind-driven rains. If not, a hydrophobic masonry sealant can be applied per the manufacturer’s instructions.