No Laughing Matter: Why Your Home's Brick Walls Are Cracking Up!

Owning a brick home has been the dream for many homebuyers throughout history. Known to be exceptionally strong and resistant to wind, termites, weather, and many other destructive influences, brick homes also rank high on the wish list because they do not require annual maintenance, such as painting. Unfortunately, however, they are not completely maintenance-free and some will develop cracking that homeowners should not ignore. If you are the owner of a brick home that is experiencing this type of problem, keep reading to discover what the cracks mean and what should be done about them.

What Is Thermal Expansion & Why Is It Important?

When any type of material contracts or expands due to temperature changes, thermal expansion is the result. Because bricks are composed of clay or clay-like materials that absorb heat readily, they will expand in size when exposed to heat. When the sun goes down, or air temperatures drop, the bricks contract. Over time, this movement can cause cracks to form in the brick walls.

In addition to the damage done to the brick, the heat absorbed by the wall can also cause any steel reinforcements and metal wall ties embedded in the wall to expand in much the same way. This thermal action can cause the bricks and masonry in the exterior walls to heave outward, causing cracks and bulges.

When masons lay a brick or masonry wall, particularly when it is a large wall, they use an expansion or control joint to offset the potential damage of thermal expansion. In most cases, an expandable sealant or joint compound is used in the control joint to keep moisture from seeping into this seam, where it might cause damage to the supporting wall or the building materials located behind the bricks.

Foundation & Settlement Cracks

In addition to thermal expansion, brick walls can also experience additional types of cracks, including those caused by foundation and settlement issues. Stair-step, diagonal and cracks with uneven edges should all be taken very seriously when they appear on the exterior brick walls of a home.

Much of the strength and durability of a brick wall comes from sheer weight. Since an average brick wall weighs about more than forty pounds per square foot, it becomes easy to see how heavy each brick wall of a home can be. To remain stable and crack-free, a brick wall must be laid upon a sturdy well-built foundation capable of supporting this immense weight.

If the foundation is not properly sized and reinforced, it cannot withstand the weight of the walls, and over a period of time, will begin to sink or shift. When this happens, the accompanying motion is transferred to the brick walls, causing cracks to develop.

When these cracks occur in a stair step or diagonal pattern and cause the bricks to separate along the mortar joints, it is wise to repair them quickly before time, moisture and temperature changes cause them to enlarge. Unless the damage is extreme, the crack can be repaired by a process known as tuck-pointing.

In this process, the masonry professional removes the old masonry compound and then "tucks" new masonry into the joints between the bricks. This process restores the appearance of the brick wall, seals out moisture and helps it remain strong.

Prevent Cracks in Older Brick Walls by Replacing Worn Mortar Joints

When mortar joints deteriorate, they can weaken and make the wall more susceptible to cracking. Vines that attach themselves to the masonry joints, weather and many other factors can cause this to occur. Making a point to look at each wall annually will help ensure that this damage is discovered early, before it becomes serious. Homeowners who notice this deterioration can help maintain the strength of their brick walls by the having the damaged mortar replaced periodically by a reputable tuck-pointing expert. 

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