Soft Wash Roof Cleaning is a process primarily used in the USA. The process involves applying a chemical to the roof tiles via low pressure to eliminate moss, algae and other pollutants.
Roofs in the USA are mainly constructed using roof 'shingles' and not concrete or clay tiles as used in the UK. The majority of these roof 'shingles' are made from Asphalt. A very similar material to the roofing felt used on flat roofs in the UK. Hence, it is not feasible to wash these 'shingles' using pressure washing.
Numerous UK based 'roof cleaning' companies have adopted a similar approach and even 'sell' the roof cleaning system as environment-friendly which is frankly nonsense. All of these chemicals (Fungicidal washes) are highly toxic to aquatic life due to the common 'shared' ingredient Didecyldimethylammonium Chloride. As stated in a typical product data sheet - AlgoClear 'Causes burns, very toxic to aquatic organisms, dangerous to the environment' - Yet the product is marketed as environmentally friendly!
For the Soft wash process to work, large moss deposits are firstly removed manually, usually by metal hand tools or wire brushes; this mechanical action can cause more damage to roof tiles then using 'controlled' pressure washing. The majority of these Soft wash companies use little or no safety equipment while scraping the roofs, this practice is illegal as it breaks basic working at heights regulations, it is wise to check with the roof cleaning company what safety measures they will implement while cleaning, You may be surprised by the answer!
After the scraping a chemical (Fungicidal wash) is applied to the roofing tiles usually from the ground level via a telescopic lance, this process is fraught with danger as the spray can easily drift onto neighbouring properties, windows, greenery, or even worse ponds! Hence, this process should only take place when the weather is calm with no wind! Remaining moss may die within a few months. However, lichens can take well over a year to die! Repeat chemical treatments may be required to achieve satisfactory results. Once complete the gutter system should be vacuumed to remove the remaining debris that has fallen from the roof. This process should be repeated after six months to remove remaining debris that has fallen off the roof.
Pro for the method
- Only basic equipment applied
- Operators require no training
Con for the method
- Results can take over a year
- Weather dependent (You can not use the chemical while it is cold, raining or in windy conditions due to spray drift)
- Mechanical scraping can damage tiles
- Gutters require a repeat clean months after the initial clean
- No option to protect the tiles from future algae/moss growth or weathering by applying a roof coating
Please note the method we use is pressure washing, it should be noted however we use controlled 'pressure washing' for all of our roof cleaning. The pressure and water flow are preset via clever gauges on the pressure washer to prevent any damage to the roof tiles. We have a vast amount of experience and have been pressure washing roofs/Repairing roofs since 2002.