Brickwork Spalling

Brickwork spalling is one of the most common defects we come across, particularly in residential properties.

Spalling is defined as a process whereby the face of a brick will ‘blow’ giving an eroded or cracked and flaking appearance, often at lower level within a wall but occurring at any height where the conditions are sufficient for the process to begin.

When water freezes it expands by approximately 9% in volume, if there is too high a moisture content within a brick or joint it will shatter/blow the face of the brick/joint. Water will always find the path of least resistance and therefore if the density of the mortar is a lot greater than that of the brick, the water will evaporate via the brick rather than the mortar. Therefore when temperatures drop during the colder periods of the year the water in the face of the brick will expand leading to the ‘blown’ face we can see above.

Spalling can be caused by a number of different reasons the main 2 are summarised below:

  • If bricks are replaced newer bricks can be ‘harder’ and have a ‘capping’ which discharges water away. The older bricks considered ‘soft’ tend to be flat. They therefore have an increased water flow over them and higher absorbance which in return causes spalling.
  • Mortar usually accounts for approximately 17.5% of a wall built in a standard stretcher bond (cavity wall), therefore making it essential to have the correct ratio within the mix to ensure best performance of the wall. If the wrong mortar mixture is used it can be less porous than the brick face; the brick therefore absorbs more than the mortar causing it to spall.

Spalling therefore most often occurs in older brick built buildings, commonly with softer red bricks which are very porous and where the builder has incorrectly specified a mortar without lime.

If you are having issues with spalling brickwork, our team would be happy to arrange an inspection and provide a defect identification report. Talk to us today for more information.

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