22nd May 2021

Roof Cleaning is the process of cleaning algae, moss, lichen, and other similar fungi from the roof. This procedure extends the life of a roof and helps prevent it from getting water and frost damaged, as moss and lichen slowly destroy the roof tiles. A thorough roof clean once in a while can help prevent such damages.

Here are some methods that are often used for roof cleaning:

Roof Scraping and Biocide Treatment

Moss and lichen are removed from the surface, with special blades that match the tile profile. They are attached to long carbon fibre poles, that allow the roof to be scraped from the safety of the ground or tower scaffold.

A special roof biocide is then applied to the roof , that soaks into the concrete tiles. This will kill any remaining moss, lichen and algae, protecting the roof from regrowth for a couple of years.

Non-Pressure Soft-Wash

A non-pressure soft-wash is the application of chemicals like sodium hydroxide and lye. Hence, it is also known as chemical wash. Although this is a great way to clean algae and lichen off your roof without using any pressure, it may in turn, leave dead spots of plants and grass.

Similarly, it may lighten or discolour  the roof tiles due to the use of bleaching chemicals. We feel, it is not advisable to use this method for washing roofs, even though it is effective. Soft-washing is best used on walls, render,cladding and patios.

High-Pressure Wash

High-pressure (Jet washing) is used to remove debris and staining by removing the top protective layer from the tiles. This method is used prior to applying a new coloured protective roof coating.

It usually requires the worker to walk up to the ridge tiles and jet down towards the gutters, to avoid flooding the loft space.

Low-Pressure Wash

A low-pressure wash is a combination of both non-pressure and high-pressure but at a much lower pressure. This roof cleaning method is conducted by using a rotary sprayer attached to a carbon fibre pole. Washing the rooftop off at fairly low pressure using biodegradable detergent.

This pressure wash method will clean your roof thoroughly and gives instant results. 

A further biocide roof treatment needs to be applied to give lasting results.

Roof cleaning can be very difficult for someone who has no experience and know-how. Please keep in mind that balancing on your roof or working off ladders is dangerous and it will be difficult for you to manage on your own. Therefore, professional advice and roof cleaning is advised.