Which moss removal method for your roof?
By the Toiture Wash team · Updated on 20 October 2026 · 5 min read
Short answer. There are three main ways to remove moss from a roof: high-pressure cleaning, brushing or scraping by hand, and anti-moss treatment alone, which works slowly with the rain. High pressure is the fastest and most thorough on a healthy roof, provided it is adjusted to the roof covering, but some tile manufacturers advise against it; treatment alone is the gentlest but takes months; the brush suits small surfaces. At Toiture Wash, every moss removal ends with a treatment included in the price: depending on your roof, a colourless water repellent or an algicide product.
The methods, side by side
| Method | Principle | Result | Limits |
|---|---|---|---|
| High pressure | a powerful water jet tears off moss and deposits | immediate, roof visibly clean | if badly set, it wears a porous tile or dislodges an element; sprays water onto the surrounding areas |
| Brush or scraper | the moss is removed by hand | immediate on moss, partial on lichens | slow, means a lot of walking on the roof |
| Treatment alone | an anti-moss product is sprayed, the moss dies and the rain carries it away | slow: several weeks to several months | the dead moss stays visible for a while and ends up partly in the gutters |
| Low pressure with product | a cleaning product is applied, then rinsed off at low pressure | gradual, gentle on the roof covering | depends on the product; rinsing and surrounding areas need watching |
| Hot water or steam | water heated, at moderate pressure | immediate, no product for the cleaning | specific equipment; the result depends as much on skill as on temperature |
High pressure: fast, if it is properly controlled
This is the most common method among professionals. Three settings make the difference between a clean result and a damaged tile:
- Pressure and nozzle: matched to the material and its condition.
- Angle: the jet must follow the direction of the rainwater, from top to bottom, so as not to push water under the overlaps.
- Distance: a jet that is too close concentrates its force on a small area.
Cleaning also removes part of the worn surface film of the tile. Every Toiture Wash moss removal ends with a treatment, included in the price: depending on your roof, a colourless water repellent, which waterproofs it, or an algicide, fungicide and bactericide product, which slows down moss regrowth.
What manufacturers say. Their opinions differ, and it is worth knowing them. Wienerberger, which makes Koramic tiles, advises avoiding high-pressure washers and aggressive cleaners, in favour of a soft brush or a low-pressure roof cleaner. Eternit points out that strong water pressure can cause leaks on its corrugated sheets. On its American site, the natural slate maker Cupa Pizarras accepts the pressure washer in most cases, with precautions (spray the water from top to bottom, never upwards), but first recommends a thick brush and vinegar.
The garden high-pressure washer (often called a "Kärcher") is not the only problem: the most dangerous part is working at height, on a slippery roof. Our guide Removing moss from your roof yourself? details the risks.
The brush: for small surfaces
Scraping off moss with a brush or scraper suits a canopy, an extension or a small low roof. On a whole roof it is slow, and scraping often leaves embedded lichens behind. Time spent on the roof is also time spent risking a fall and walking on the roof covering.
Treatment alone: gentle, but slow
An anti-moss product sprayed on the roof kills the moss, which the rain then carries away bit by bit. It is the gentlest method for the roof covering, but:
- the result shows after weeks or months, not on the same day;
- the dead moss stays attached for a while and ends up partly in the gutters, which will need cleaning;
- it does not remove embedded deposits or lichens.
It has its place for maintaining a roof that is already clean, or when the roof covering is too fragile to be cleaned.
Hot water, steam, low pressure: the variants
Some companies promote hot water or steam, others a low pressure with a cleaning product applied beforehand (sometimes called "softwash"). These are variants of the same idea: loosening the moss with less mechanical force. The result depends as much on skill, product and time spent as on the name of the method. Whatever the method advertised, always ask which product is used, what is planned if you have a rainwater tank, and what is included in the price.
And the drone?
A drone can spray a treatment on a roof without anyone going up. It does not remove the moss, so it does not replace cleaning; its use is regulated by drone flight rules, especially in towns. It can be used to inspect an inaccessible roof or to treat a large surface.
Tiles, slates, fibre cement: the method follows the roof covering
- Clay tiles: the pressure is set according to age and porosity; a frost-damaged or flaking tile is pointed out before starting.
- Concrete tiles: tougher under cleaning, they lose their colour over time; paint can follow.
- Natural slates: not very porous, they clean well, but a slate can crack underfoot or shift if the jet gets underneath. See Moss removal on a slate roof.
- Fibre cement and older fibre-cement slates: no cleaning method of any kind until you know whether there is asbestos. See Does my roof contain asbestos?
Frequently asked questions
Does high pressure damage tiles?
It can if it is badly set or badly directed, especially on an old, porous tile, and some manufacturers, such as Wienerberger for its Koramic tiles, advise against it.
What is the most environmentally friendly method?
The one that sends neither an aggressive product into the garden nor cleaning water into the tank. Bleach should be ruled out. For high pressure, water is enough for the cleaning; the treatment that follows is chosen and dosed with care. An anti-moss product must be an authorised biocide, with a number you can check on biocide.be.
Can you remove moss from a roof without a product?
Yes: high pressure with clean water removes the moss. The treatment comes afterwards: a water repellent waterproofs the roof, or an algicide product slows down moss regrowth.
Sources
- Wienerberger, Tips for maintaining a roof (in French).
- Eternit, Moss on the roof (in French).
- Cupa Pizarras, How do you clean a slate roof?.
- Federal Public Service Public Health (SPF Santé publique), types of biocidal products.