Cracking the Code: Understanding Vertical Corner Brickwork Cracks

Vertical Corner Masonry Cracking

Building materials often change in volume in response to changes in temperature and/or moisture, Bricks the focus of this article expands naturally over time.

Cracking of brickwork is a common defect and issue often inspected by engineers. The cracking pattern, size and location along with the construction type of the building assists in diagnosing and providing a rectification plan for the crack.

One cracking pattern commonly encountered is the vertical cracking found along the corners of the brickwork. Our recent case study shown below.

This pattern of cracking is a clear indication of thermal expansion which has distinct characteristics.

Walls that intersect will naturally expand in the direction of their juncture. This causes stress on one or both sides of the corners. The cracking as a result of this distress appears at the first vertical joint on one side of the walls corner. Other thermal factors such as a particular face exposed to additional sunlight then the linking face exacerbates the issue. Other restraints such as slabs, lintels and the like located in close proximity to the corner provides a restraint to the brickwork and a factor in the formation of the cracks. The below examples show the thermal effects of a corner and an offset arrangement within a brick façade.

Corner Intersecting Walls

Movement at Offset Walls

Expansion joints are critical in preventing cracks formed at corners of the building. Often designers and builders space these joints to meet the minimum requirements however it is also essential to place expansion joints in areas of the brickwork that is prone to cracking and incur higher thermal stresses such as corners and offset walls.

In prevention, an expansion joint should be placed within 3m of the corner of either wall however not required to both sides. Often overlooked, the distance from this expansion joint from the corner to the adjacent vertical expansion joint should not exceed the spacing of joints placed in a straight wall.

Offset wall cracking is caused as the parallel walls expand towards the offset, this in turn rotates the shorter masonry leg of the offset wall. A single expansion joint at the offset will allow the parallel walls to expand and prevent the cracking to the offset.