Brick is one of the most used materials in the construction and housing industry. Working with bricks can be a little tricky and confusing, and that's one of the reasons why we need to have expansion joints. Some contractors have failed to execute some simple steps and have paid the price with costly reparations after the job was completed.
Expansion joints will prevent or minimize cracks when they are placed horizontally or vertically, but be sure to locate those joints at the right location. Otherwise, you might not be solving the problem or preventing it from happening.
Bricks Expansion Joint
Bricks, like other construction materials, will change in volume with changes in temperature. It will all depend on where the brick is located and what conditions are being exerted upon it. Bricks will also increase in size due to expansion by moisture and the absorption of water. Engineers will calculate how much it will expand following some basic calculations and studying the behavior of the materials acting upon it.
Using expansion joints in your brickwork will separate your bricks into small segments, in which, each segment will act individually, and will behave separately from other segments. The expansion joints will reduce brick cracking by changes in temperature, moisture, creep and/or settlement, either horizontally or vertically.
Use pre-molded foam or neoprene in the brick expansion joint. It can be done, by leaving a continuous opening through the brick wythe and filling it. Finish this joint with backer rod and elastomeric sealant material to prevent moisture and water going into the brick joint.
Make sure that the expansion joint material runs through the full thickness of the wythe. It will avoid the mortar and other debris that will clog the joint.
- Do not use an incompressible material in the joint.
Vertical and Expansion Joints in Bricks
Every joint in the brickwork is different. There are a lot of conditions varying from one scene to another, so don’t treat every joint the same way. Vertical joints in brickwork will ideally be placed every 25 feet. Vertical joints should be located at corners, offsets, setbacks, openings, wall intersections, changes in direction, certain heights and long walls.
The engineer should locate the brick expansion joints, not the mason. It is a complex technical issue and should be treated with responsibility. Brick expansion joints should be placed where different walls encounter each other, reducing thus the possibility of cracks due to differential settlement. The joint must be located in the interior corner or at least 12” from the corner, creating a stable connection to other members of the building.
Brick Horizontal Joint
Horizontal joints must be located underneath the shelf angle, but please remove temporary shims used to hold the angle in position during the construction process. The joint will be used to resemble the mortar joint so make sure it is finished properly.
Sometimes using lipped bricks, with at least a half-inch in-depth, is required for large horizontal joints, because they reduce the impact of the joint. Lipped bricks should be made by the manufacturer, and not in the project itself. It will allow a greater quality and reduce the errors due to weak bricks. Finally, do not allow contact between the lipped brick and the brickwork below, it might cause problems in the future with its integrity.
Other Factors Affecting Bricks in Construction
The above issues are probably the most common ones that can generate cracks in bricks, but they are not the only ones. Be sure also to review and analyze the following items:
- Type of bricks used
- Location of the brick
- Moisture in the bricks
- Mortar creep