How do you clean exterior brick?
Brick gets dirty from pollution, soot, algae and calcium splashes. It is strong, but its mortar is fragile: the right method cleans without damaging it.
Updated
Quick answer
To clean exterior brick, wet the wall, apply a diluted masonry cleaner, scrub with a soft-bristle brush, then rinse with clean water at low pressure, from the top down. Avoid acid and high pressure, which dig out the mortar joints, and work in mild weather with no risk of frost.
Time: 2 to 4 hours for a commercial wall
What you need
- Detergent-based masonry cleaner, biodegradable
- Long-handled soft-bristle (nylon) brush
- Garden hose or a pressure washer set low with a wide nozzle (40°)
- Garden sprayer to apply the product
- Safety glasses, gloves, tarps to protect plants
Steps
- 1
Check the condition of the wall
Look for cracked joints or crumbling bricks: have them repaired before any washing, otherwise water seeps in.
- 2
Wet the brick
Hose the wall down with clean water: brick saturated with water absorbs less of the product and the dissolved dirt.
- 3
Apply the cleaner
Spray the diluted cleaner from the bottom up and let it work for the time indicated, without letting it dry.
- 4
Scrub
Brush the dirty areas with the soft-bristle brush, in circular motions.
- 5
Rinse
Rinse thoroughly from the top down, with the hose or at low pressure, wide nozzle, at least 30 cm (12 in.) from the wall.
- 6
Let it dry and inspect
Once dry, a white film may appear: this is efflorescence, which is treated separately (see our guide).
Mistakes to avoid
- Using muriatic acid without training: it burns the brick and leaves stains.
- Washing in freezing weather or just before: the water that seeps in makes the brick crack.
- Aiming a powerful jet at the mortar joints.
When should you call a professional?
For a tall facade, very blackened or old bricks, or if the wash water has to be collected, leave the job to an equipped crew. HygiePro washes the brick facades of businesses across Greater Montreal.
Frequently asked questions
What is the best cleaner for brick?
A detergent-based masonry cleaner, diluted according to the manufacturer. Acidic cleaners are for professionals only: in the wrong dose, they burn the brick and the mortar.
How do you bring back the colour of red bricks?
A wash with masonry cleaner followed by a good rinse revives the colour. Avoid glossy “enhancers”: they keep the brick from breathing.
Can you pressure wash brick at high pressure?
Not at high pressure: it digs out the joints and can flake the surface of the brick. Use the lowest pressure that works, with a wide nozzle.