What Causes Brick Deterioration, or Spalling, to Occur?
There are numerous conditions on a building that can be contributing factors, but the primary cause is moisture infiltrating the brick façade. When moisture infiltrates a brick façade and saturated brick units freeze during the winter months, the freezing moisture places expansive pressure on the more dense back of the brick face causing delamination or spalling. This freeze/thaw phenomenon is commonly referred to as spalling. Once the face of a brick spalls, the inner, more absorptive portion becomes exposed to the exterior elements and additional deterioration becomes accelerated.
Open mortar joints, open sealant joints, defective flashings, leaking gutters & downspouts are building conditions that can allow significant amounts of moisture to enter brick facades. Open capstone joints on top of parapet walls cause significant brick spalling because melting snow and ice soaks straight into the brick below. Furthermore, there is not a controlled climate on either side of a parapet wall, so these areas freeze harder during the winter months causing worse damage.
Another building condition causing bricks to spall is the installation of mortar that is too high in compressive strength. When moisture infiltrates a brick façade, it needs to have the ability to dry naturally. Most of the moisture evaporation process occurs through the mortar joints, so if the mortar is too hard, it drastically slows the evaporation and drying process. This can cause the brick units to stay saturated into the cold winter months and lead to spalling.
How to Prevent Brick Deterioration
The only good way to repair spalled bricks is to replace them which can be costly. Finding a good brick match on older buildings can prove to be difficult, as well. The best course of action to defend against spalling bricks is to keep mortar joints, sealant joints, flashing joints, gutters & downspouts well maintained. If you start to see brick spalling on your building you should act sooner, rather than later, to identify the cause and solution. Typically, once you start to see spalling brick, the problem progresses quickly.