How do I remove moss & algae from bricks & paving?

FAQ Category: 

  • Maintaining bricks
Moss and algae are usually green
LIchens form dark spots, and often look like stains

It is common to find growths such as algae, lichens, liverworts and moss growing on hard surfaces. Contrary to popular belief, they do not damage what they are growing on, but can cause patios, drives, paths and steps to become slippery.

Moss, lichens and algae should not grow on clay bricks unless the area is heavily shaded, is under trees, or is not laid to an adequate fall. If such growth does occur and is considered undesirable then the area should be treated with a proprietary moss killer used in accordance with the manufacturer’s instructions.Such products take some days to be effective and work best when applied during a spell of dry weather. Any thick growths should be scraped off first and the chemical treatment well brushed in.

Some treatments leave a residue to discourage the re-growth of the moss and algae, but this will only be of limited value if the paving remains damp and in shade.

Non-chemical control

  • Dislodge moss from between paving by running a sharp knife along the cracks. Alternatively, use a block paving brush with a long handle, narrow head and wire bristles for effective cleaning without stooping
  • A pressure washer will remove moss and algae effectively.  However, use this method with care in areas where drainage is unsatisfactory as the extra water could exacerbate damp problems. Always wear goggles when using a pressure washer.
  • Brush hard surfaces with a stiff broom on a regular basis to help prevent growths from taking hold. Raking loose surfaces such as gravel helps to keep these areas free of both moss and weeds
  • Prune overhanging plants to improve air flow – this will allow the drying effects of sun and wind to reach the site
  • Ensure surfaces slope slightly to prevent standing water
  • Improving drainage in the surrounding area will also help to deter growths. Dig out shallow channels along the edges of paths, patios and drives and fill with coarse gravel to absorb run off water
  • Fork over beds close to damp surfaces to maximise drainage and water absorption
  • Only pave areas essential for access. Choose permeable paving when constructing new hard surfaces and keep drains clear of leaves and debris
  • Surface finishes that are raised to give grip in wet weather are ideal for shady spots. Spreading coarse sand over garden steps is another simple anti-slip solution