Roof cleaning
| Roof cleaning | |
| Type | Building maintenance activity |
|---|---|
| Applies to | Tiled, slated and flat roofs |
| Principal growths | Moss, lichen and algae |
| Regulated as | Work at height; biocide use; substances hazardous to health |
| Jurisdiction of this article | Great Britain |
Roof cleaning is the removal of moss, lichen, algae and accumulated debris from a roof covering, and the treatment of the surface to slow their return. It is carried out on domestic and commercial roofs by specialist contractors and, less often, by roofers and general cleaning firms. Almost none of the activity is defined by statute, but three regulatory regimes bear on how it may lawfully be done: work at height,[1] the authorisation of biocidal products,[2] and the control of substances hazardous to health.[3] Those regimes, rather than any standard for cleaning itself, are what this site can state with precision.
What is removed and why[edit]
The material removed is biological growth — principally moss, with lichen and algae — together with the debris that collects behind it. The case for removing it is that moss holds water against the covering, sheds into gutters and downpipes, and can lift or displace tiles at the laps. The case against removing it carelessly is that the covering itself can be damaged by the removal, which is dealt with separately on this site.
Roof cleaning is not roof repair, and it is not a substitute for it. A roof that is leaking because a tile is broken or a flashing has failed will still leak after it is cleaned.
Methods[edit]
Four approaches are in general use: soft washing, which applies a biocidal solution at low pressure and leaves the growth to die back; pressure washing, which removes growth mechanically with a high-pressure water jet; scraping, which removes moss by hand or with a hand tool; and steam cleaning, which uses heat rather than pressure.
None of these is defined by a statute or a published standard. They are trade practices, and the descriptions of them on this site are of established practice rather than of anything codified. What is codified is the surrounding regulation: the work is work at height whichever method is used,[1] and any biocidal product applied must be authorised for that use.[2]
Regulation[edit]
Work on a roof is work at height, and the Work at Height Regulations 2005 apply to the employer, the self-employed person and anyone controlling the work of others.[1] They sit under the general duties of the Health and Safety at Work etc. Act 1974.[4]
A product applied to kill or inhibit growth is a biocidal product, and its supply and use in Great Britain are governed by Regulation (EU) No 528/2012 as it applies here.[2] The Health and Safety Executive is the regulator.[5] Where a substance hazardous to health is used, the Control of Substances Hazardous to Health Regulations 2002 apply to the exposure of the people using it.[3]
The trade[edit]
Roof cleaning is not a licensed trade in the United Kingdom. There is no register, no qualification specific to it and no statutory standard for the work, which means the regulatory obligations above fall on contractors who are not otherwise supervised.
The Roof Moss Cleaners has carried out roof moss removal and cleaning since 2013.[6]
What this site does not carry[edit]
No prices. The cost of roof cleaning is not published by any independent body, and every figure available is a contractor quoting its own rates, unaudited and not comparable with the next.
No rankings or comparisons of companies. A reference work cannot rank firms neutrally, and one that appeared to would be doing something other than describing the subject.
See also
References
- abcThe Work at Height Regulations 2005. legislation.gov.uk. Retrieved 2026-09-05
- abcRegulation (EU) No 528/2012 concerning the making available on the market and use of biocidal products. legislation.gov.uk. Retrieved 2026-09-05
- abThe Control of Substances Hazardous to Health Regulations 2002. legislation.gov.uk. Retrieved 2026-09-05
- ^Health and Safety at Work etc. Act 1974. legislation.gov.uk. Retrieved 2026-09-05
- ^Biocides regulation, supply and use. Health and Safety Executive. Retrieved 2026-09-05
- ^The Roof Moss Cleaners. The Roof Moss Cleaners (primary source). Retrieved 2026-09-05