Masonry repair is essential for keeping historic brick and stone walls at their peak performance as the building designer originally intended. This often requires a detailed condition assessment to fully understand the issue and select appropriate treatment options.
Small issues can balloon into expensive problems if not addressed early. It’s best to get a professional to inspect and address masonry issues before they worsen.
Cracks
Brick walls can crack for many reasons. Most often these cracks are cosmetic and do not cause serious structural problems. Nonetheless, they should be addressed to ensure that they don’t worsen over time.
It’s important to determine whether a crack is active or dormant before attempting to repair it. Active cracks are an indication that the underlying problem is still at work and should be resolved before further damage occurs. For example, if you notice a vertical crack that has widened over time and then stopped it may indicate a problem with the foundation of the building.
To fix cracks within the mortar joints themselves, remove any growth in or around the crack and clean it thoroughly. Next, use a hammer and chisel to remove the loose mortar from the joint. Be sure to only remove a third of the thickness of the joint itself, for structural reasons.
A mortar repair compound can be used to fill the gap. Once the crack is filled it should be tamper-proof, caulked, and cleaned to ensure that moisture doesn’t seep into the structure of the building. To prevent future shrinkage cracking, control joints should be built into the wall to reduce restraint and allow longitudinal movement.
Leaks
Moisture penetration is a major threat to masonry structures such as chimneys, brick walls and porches. It weakens the structure resulting in major defects and even collapse if left unattended. Moisture infiltration into masonry comes in the form of rain, melting snow and frost/ice formation which can happen year-round causing damage to your masonry structures.
Leaks in masonry are typically found in the form of deteriorating mortar joints. These joints are usually caused by rain driven by winds saturating the brick wall resulting in holes and ledges in the mortar that allow rain to seep into the structure. Leaks also occur in masonry foundation walls due to the build up of moisture below grade that erodes the masonry mortar and causes water infiltration.
In older houses with stone or brick foundations it is common for the build up of water to saturate the masonry mortar and cause leakage and floods in the basement. This occurs due to poor grading and drainage that allows water to accumulate and not move away from the foundation.
Another source of leaking in brick masonry is the freeze-thaw cycle. During the winter, water soaks into the absorbent brick and when it thaws, it expands exerting pressure on the brick and mortar which can then result in cracks in the brick wall. Efflorescence (white or gray crystalline deposits on brick surfaces) is another indicator of water infiltration into a brick structure.
Waterproofing
Just as tuckpointing safeguards mortar, waterproofing protects brick from the elements that cause serious damage. Unlike normal paints and sealants that form a film on the surface of masonry, waterproofing materials penetrate deep into the surface of the brick or masonry to prevent water penetration and damage.
Masonry waterproofing is an important service that should be incorporated into preventative maintenance. When left unchecked, water exposure can cause serious damage to bricks and masonry, such as spalling, deterioration, and erosion. Water penetration causes pressure fractures in concrete walls, and freeze/thaw cycles in masonry structures that slowly erode the structure’s raw material.
Surface treatment repellents are a common approach to protecting brick surfaces. These products minimize masonry deterioration, efflorescence and surface staining with one application. Surface treatments should be able to allow for vapor transmission, as those that are impermeable can blister and peel.
Some integral water repellents are soluble in alkali, making them less than ideal for new construction or over existing masonry. Also, these products may decrease bond strength between mortar and masonry units. Alternatively, a concrete parging process can be used to provide the same protection as integral water repellents without affecting the strength of the mortar bond. However, it should be noted that this method may not provide full protection since it does not address cracks and other imperfections in the masonry.
Restoration
Masonry is a construction method that uses bricks or stones with cement mortar to hold them together. This technique is particularly useful for historic buildings that may need to be preserved for historical significance. Over time, even the best masonry structures will need some form of masonry repair or restoration. Small damages like hairline cracks can be easily repaired with caulking, but bigger issues will require professional attention to prevent the damage from getting worse.
Once a condition assessment has been conducted, and any necessary temporary stabilization installed for imminent hazards, options for masonry repair or restoration can be developed. Repair techniques generally involve repointing, brick and stone replacement/restoration and re-building of damaged or deteriorated masonry surfaces and structures. This work is typically done using materials that match the original materials in terms of type and color.
Masonry restoration can be a large project and may include the complete removal of old mortar, bricks and stone, then rebuilding with new materials. This process will also restore the original appearance of a structure. It’s important to note that although masonry is strong in compression, it is vulnerable to tensile stresses which are often observed as cracking, spalling (a hand-sized chunk of material missing) and scaling (thin outer surface). This means that it’s essential to monitor these structures for any signs of distress such as these.