Repair efflorescence.

Efflorescence — the white powdery stain on new and damp brickwork — is one of the most common bricklayer callbacks. It looks alarming but most cases clear naturally. The few that don't may signal a serious damp problem. This guide covers what causes efflorescence, when to worry, and how to treat it without making things worse.

The cause: dissolved salts in mortar or brick migrate to the surface as water evaporates. Once deposited, they form the visible white crystals.

Common Causes

• New brickwork: salts in unused mortar/brick — clears over 6–12 months.
• Persistent damp: water continuously brings salts; clearing needs the damp fixed.
• Defective DPC: damp rising; salts deposit at DPC level.
• Wind-driven rain saturation: walls drying brings salts.
• Pressure-washing or cleaning: water entering walls brings salts on drying.

How to Diagnose

• New stain on new wall: usually primary efflorescence — wait 6–12 months.
• Recurring stain: usually persistent damp — fix the source.
• Stain at specific level: usually DPC failure at that height.
• Stain after rain: wind-driven rain saturation — consider rendering or pointing.

Typical Costs

DIY or Professional?

Brushing or gentle washing — DIY. Acid cleaning, specialist diagnosis, and damp investigation — professional.

Choosing the Right Tradesperson

• For recurring efflorescence, hire a damp specialist not just a bricklayer.
• Get a written diagnosis before agreeing to treatment.
• Avoid sales-driven damp companies — recommend independent diagnosis.

UK Regulations

• Listed properties: consent for any chemical cleaning.
• DPC injection requires Building Regs notification.

Common Problems

• Treating symptoms not cause — efflorescence returns.
• Acid damage — wrong concentration etches brick.
• Over-diagnosed damp — efflorescence sold as evidence of expensive treatment.
• DIY chemical injury — strong cleaners burn skin and eyes.
• Persistent recurring stain — usually means real damp problem.

Frequently Asked Questions