What About Brick Homes?

Bricks aren’t waterproof—and treating them like they are is where a lot of moisture and mould problems start.

Most standard clay bricks are actually porous, meaning they absorb and release moisture. That’s by design. A typical brick wall system (brick veneer or double brick) is built to manage water, not stop it completely. Rain can soak into the outer bricklayer, but it should then drain down the cavity and escape through weep holes, while airflow helps it dry out.

So do you need to seal them?

Usually, no—not by default.

Sealing bricks can sometimes do more harm than good if it’s done incorrectly.

Here’s how it breaks down:

When you generally should NOT seal bricks:

  • On modern brick veneer homes with proper cavities and weep holes
  • If the bricks are in good condition and drying properly
  • In humid climates (like the Sunshine Coast), where trapping moisture can lead to hidden mould issues

Applying a non-breathable sealer can trap moisture inside the wall, which can:

  • Drive dampness inward
  • Cause mould growth inside wall cavities
  • Lead to efflorescence (white salts) and deterioration over time

When sealing can make sense:

  • Older homes with very porous or deteriorating bricks
  • Areas exposed to constant wind-driven rain
  • If you’re using a breathable penetrating sealer (this is key—not a surface coating)
  • After fixing any underlying issues like cracked mortar, poor drainage, or blocked weep holes

The better approach (especially for mould prevention):

Focus on moisture control, not waterproofing the bricks:

  • Keep weep holes clear so water can escape
  • Maintain gutters and downpipes
  • Fix cracks in mortar (repointing if needed)
  • Ensure good drainage away from the house
  • Allow walls to breathe and dry naturally

Bottom line:

Bricks are meant to get wet and then dry out. Sealing them is only appropriate in specific situations—and if you do it, it must be with a breathable product; otherwise you risk locking moisture in and creating a much bigger mould problem.

If you want, I can tell you how to tell if your specific brickwork actually needs sealing or not—that’s usually the smarter next step.