The best different ways to clean algae and moss from concrete, brick and stone surfaces

When removing algae and moss from any stone edifice, including monuments, listed buildings, graves and tombstones, or any type of concrete or brick facade, you need to make sure that the products and techniques that you use don’t cause further damage to the surface.

Look after the exterior of your building

You should never use cleaning or preservative products or treatments on important, cultural stonework without discussing the job with a conservation architect first. Ensure you opt for a phosphate and acid free product which is not only environmentally friendly, but that won’t have a negative impact on the building facade. APT’s Algae Free product is an example of the sort of product that is usually endorsed by architects who work on the conservation of listed and historical buildings.

Power washing is used by many cleaning companies to clean off algae and other organic matter from building surfaces. However, power washing can cause major issues, as the water jets tend to remove the sand between the building’s bricks, often lifting them out of place. Care needs to be taken when cleaning these buildings and experienced operatives will know to work at high angles to prevent damage to brickwork. Water, in some cases should not be used in historical conservation.

Gentler techniques such as soda blasting (, which is by far the most popular holistic approach or steam cleaning are a better options for historic and listed buildings. With steam cleaning we suggest that the algae is cleaned off with a suitable product first then a gentle, steam wash using low powered pressure washers can be extremely effective. Sand blasting should also be avoided at all costs as this is a harsh form of cleaning and can cause irreparable damage. What’s more, if you blast the original glaze off a brick surface in cold weather conditions then the surface is more prone to absorbing water and in turn will grow more algae and moss.

How can you minimise the risk of algae growth?

To minimise the likelihood of moss and algae attacking your building, there are some specific measures you can take. For example, you should trim back trees whose branches overshadow the building and clear away all organic debris such as leaves or pine needles which collect in gutters and other crevices.

Routine cleaning and maintenance should not be ignored. If you keep the stone, brick or concrete surface of any building clean and treated, then you will minimise the build-up of algae and reduce the need for constant cleaning (which could in turn cause long term deterioration to the surface).

At APT-ICC we offer local authorities and conservation architects specialist advice and guidance in terms of which products should be used to get rid of algae and moss from historic listed buildings and commercial buildings including killing off the spores; as well as which cleaning techniques are the most appropriate to avoid causing any long term damage.
For further details, visit our commercial chemicals cleaning website at or call the APT team on 0800 0723 773.