Why Would a Brick Wall Crack?

Thermal

• Thermal expansion, caused by a brick wall's exposure to harsh sunlight, may lead to the brick moving and cracking. Buildings that have cracks in their brickwork due to thermal expansion often have the most damage on their south side, which typically receives the strongest sunlight. Another factor, in some cases, is the weak connection between brick veneer vulnerable to thermal expansion and the supporting structure behind the veneer, such as a concrete wall.

Settlement

• Homes typically exhibit some minor settling over time, and this may show up as small cracks in the bricks. Cracks about 1/5-inch long or less usually do not indicate that any structural problem exists. Larger cracks point to more serious defects that have a variety of causes. The house might have been built with softer soil on one side than the other, causing it to settle unevenly. A poorly constructed foundation is another possibility.

Combining

• Cracks may occur when different types of bricks combine in the same wall or when other materials have been added to the wall. For example, a decorative course using bricks or stone that does not match the type of brick used as the primary material for the wall may cause problems. The different materials do not move at the same rate and cracks can result. Using concrete with brickwork might also lead to cracked bricks.

Water

• Water can enter a brick wall through the mortar joints and cause serious damage including cracking and loosening of the mortar. Any brick wall subject to wind-blown rain may fall victim to this problem. Applying a waterproof sealant to the brick should solve the difficulty, according to the Ask the Builder website. The sealant should contain silane or siloxane, two effective waterproofing compounds. Two coats might be necessary to fully protect the brick from rain penetration.