stair-step brick veneer crack
Brick veneer cracking is a reliable indicator of slab foundation distortion so long as you know what to look for. There are only four causes of brick veneer cracking: thermal cracking due to shrinking and swelling of the brick and mortar caused by temperature changes, cracking due to impact loads, cracking due to deteriorating steel lintels above doors, and windows due to foundation distortion.
Soldier brick cracks
Openings in the soldier brick mortar are not normally caused by foundation distortion. An exception is shown in the photo below. Note that the opening is due to not in the brick or the mortar but to the bond between a soldier brick and the mortar. the
soldier course brick brick veneer crack
Diagnosing brick veneer cracking due to temperature changes
These cracks are usually vertical and are essentially the same width from top to bottom. If they are a minimum of three movement joints in a brick veneer wall, thermal cracks will show up mainly in the joints.
combination brick veneer crack
Cracks due to impact loads
Cracks due to impact are usually obvious. There is usually a large hole in the brick veneer and lots of brick debris. A vehicle that is well into the house is another giveaway.
Cracks due to deteriorating steel lintels
These cracks are horizontal and come off the steel lintels. After the house is ten years old, the lintels begin to rust. When steel rusts, it initially increases in volume. In effect, the rusting lintels push the brick veneer apart above the lintel.
horizontal steel lintel crack
Brick veneer cracks & separations due to foundation distortion
These cracks are usually stair-stepped and are either wider at the top and narrower at the bottom or vice-versa. Sometimes they are vertical instead of stair-stepped, but if the crack is wider at the top than at the bottom (or vice-versa) then the most likely cause is foundation distortion.
You will sometimes see a vertical separation or crack in the brick veneer that was initially a thermal crack but has turned into a bending crack. Not knowing the history of the crack makes it nearly impossible to accurately diagnose.
Combination brick veneer cracks
The most common combination crack is a vertical crack that is wider at the top than at the bottom or vice-versa.
This combination is usually a thermal crack that later responded to sagging or heaving in the slab foundation.
Brick veneer cracking is to be expected due to the amount of distortion the slab is designed for. At a minimum, the foundation design dictates that, in some situations, the foundation will distort enough to crack brick.