Efflorescence: why bricks go white and how to fix it

If your brickwork has gone patchy white, that is efflorescence. It looks worse than it usually is, but it is worth understanding.

What it is

Natural salts in the brick and mortar dissolve in water and get carried to the surface. When the water evaporates, the salt is left behind as a white bloom.

Why it happens

New brickwork often shows it in the first months as it dries out. It can also point to water getting in where it should not, through a failed damp course or poor drainage.

What to do

• New work: it usually weathers off on its own over a season or two. A dry brush helps. Avoid hosing it, which just dissolves more salt.
• Persistent efflorescence: that is a water problem worth investigating, not just a cleaning job.
• Stubborn deposits: a proper masonry cleaner used carefully, not a random acid that can burn the brick.

If yours keeps coming back, get the cause looked at. We are happy to take a look.