What Is Efflorescence and What Does It Tell You?

If you've noticed white, chalky deposits on brick walls, plaster, or concrete, you're looking at efflorescence. It's one of the most common signs of moisture movement through masonry.

What Is Efflorescence?

Efflorescence is the deposit of soluble salts on the surface of masonry or plaster. As water moves through a wall or floor, it dissolves naturally occurring salts within the material. When the water reaches the surface and evaporates, the salts are left behind as a white, powdery or crystalline deposit.

What Does It Tell You?

The presence of efflorescence confirms that moisture has been moving through the material — but it doesn't tell you the source. That requires a proper investigation.

Common causes include: - Rising damp (salts from groundwater) - Rainwater penetration (through defective pointing or render) - Construction moisture (in new builds, this is normal and temporary) - Plumbing leaks

Should You Be Worried?

Efflorescence on new brickwork or a recently built wall is normal and will diminish over time. Persistent or recurring efflorescence on internal walls is a sign of an ongoing moisture problem that needs investigation.

Can You Remove It?

Yes — efflorescence can be brushed off with a stiff brush when dry. Do not wet it, as this re-dissolves the salts into the surface. However, removing efflorescence without addressing the moisture source means it will return.

If you're seeing efflorescence on internal walls or plaster, contact Shadbolt Plastering for a damp survey.