Brick and stone cleaning across the North East

Brick looks tough, but its face is the hardest part. Behind the fired skin the body is softer and more porous, and the mortar between the courses softer still. A high pressure lance held close can strip that skin, scour out the joints and leave a wall that soaks up more water than before.

Once the face is damaged, rain gets in more easily, frost pushes pieces away and green growth returns faster. So the aim of a brick clean is to remove dirt and growth while leaving the surface exactly as it was made.

That is why we clean brick and stone by soft washing or steam. Both rely on a solution or on heat to do the work, so the water only needs to carry the loosened dirt away.

Every wall gets a look before anything is applied. We note the type of brick or stone, whether the face is smooth or textured, how sound the pointing is and what is actually on the surface: algae, lichen, soot, salts or general grime.

Crumbling joints, spalled bricks or loose stone change the plan. In those spots we work more gently or leave them alone and tell you why. If a wall needs repointing first, we say so before we start.

Most green and black growth on brick is biological, and it clings in the pores where plain water cannot reach. Soft washing applies a dilute solution at low pressure, gives it time to work on the growth itself, then rinses it off gently.

Because the growth is killed rather than just knocked back, walls tend to stay cleaner for longer. It is the same approach we use for render cleaning, adjusted for the more porous surface of brick.

Some marks respond to heat better than to a solution: greasy grime near vents, old staining around doors and patches where a solution alone has not shifted the deposit. Steam softens these at low pressure so they can be brushed and rinsed away.

Steam also suits walls where you would rather not use a cleaning solution, such as brickwork beside a pond or a well-planted border.

White powdery patches are usually efflorescence, salts carried out of the brick as it dries. Cleaning removes what is on the surface, but if water is still moving through the wall the salts can come back; our guide to efflorescence on brickwork explains why.

Dark streaks below a chimney stack come from soot and rainwater, covered in chimney staining on brickwork. Green walls on the shaded side of a house are algae, which soft washing handles well. For a wider look at methods, read how to clean brickwork, and for what shapes a quote, see brick cleaning cost.

Many North East terraces combine soft, handmade-looking brick with sandstone sills, lintels and bay surrounds. Sandstone is softer again and marks easily, so it gets the lightest touch on the job.

Lime mortar in older walls is meant to be softer than the brick, and it can be washed out by heavy pressure. Low pressure methods leave it in place, which is the main reason they suit older houses.