Roof treatment: water repellent or anti-moss
At Toiture Wash, every moss removal ends with a treatment, included in the price of €10 per m² excl. VAT: depending on your roof, either a colourless water repellent or an algicide, fungicide and bactericide product. The water repellent is the one that waterproofs the roof: applied to the clean, dry surface, it makes rainwater bead and protects a roof covering left exposed by the cleaning.
Updated on 20 October 2026
In brief
- A treatment included in every moss removal: colourless water repellent or algicide, fungicide and bactericide product, depending on your roof. No extra charge: before comparing two quotes, check whether the treatment is included, and at what price.
- What the water repellent does: it waterproofs. Rainwater beads and runs off, and the roof covering stays drier.
- What the other treatment does: an algicide, fungicide and bactericide product, it slows down moss regrowth. The two products are not mixed: the roof receives one or the other, at the team's choice; on a hard-wearing roof, it is generally the algicide.
- What the water repellent does not do: it does not repair a cracked tile, does not stop a leak and does not change the colour. It is always colourless: a faded tile stays faded. For a new shade, see roof painting.
- When the water repellent is applied: after the moss removal, on a dry roof, in dry weather and when there is no frost. As an example, the technical data sheet of a roof water repellent sold in Belgium requires a temperature between 5 and 35 °C and at least 3 hours without rain at 20 °C.
- How long the water repellent protects: it depends on the product, the surface and the exposure. Be wary of lifespans promised without a technical data sheet: some manufacturers' data sheets state no lifespan in years.
- VAT: the same as on your moss removal quote, since the treatment is part of it.
Why protect a roof after moss removal
Moss removal takes off the moss, but also part of the surface film that time and weather have already worn. A clean tile absorbs more water than a protected one, and a roof covering that stays damp turns green again faster. This is where the water repellent comes in: water beads and runs off towards the gutter instead of entering the material. The other treatment works differently: algicide, fungicide and bactericide, it slows down moss regrowth, and it is generally the one a hard-wearing roof receives.
The treatment also means the roof needs moss removal less often: without it, moss returns faster on a roof facing north or under trees. That is why we do not sell moss removal and treatment separately: the price per m² includes both.
Colourless water repellent or roof paint: which to choose?
| Colourless water repellent | Roof paint | |
|---|---|---|
| Appearance | does not change the colour | revived or new colour |
| Protection against water | yes | yes |
| For which roof | depending on your roof: the team applies the water repellent or the algicide product | concrete tiles or suitable surfaces, in good condition |
| Price | included in the moss removal | on top of the moss removal |
Our water repellent is always colourless: we do not apply a coloured water repellent. To revive or change a shade, use paint. The guide Water repellent or roof paint: which to choose? compares the two in detail.
How we apply it
- Moss removal and rinsing of the roof, then drying: a water repellent is never applied to a wet surface.
- Choice of treatment by the team, depending on your roof: the colourless water repellent or the algicide product, never both, since they are not mixed.
- Application of the chosen treatment. The team works carefully around the house.
Water-based or solvent-based water repellent, a product that forms a film or one that penetrates without forming one: these choices are made depending on the surface. A good roof water repellent repels rain without stopping the material from drying: moisture must be able to get out.
The drawbacks of a water repellent, stated frankly
- Its lifespan is limited: it wears with sun and rain, and one day it will have to be redone.
- It does not rescue a roof at the end of its life: a frost-prone tile or one that is porous right through, or a roof covering that leaks, needs something other than a treatment.
- It needs dry weather: applied before a shower, it loses part of its effect.
- The wrong product can trap moisture: a product that stops the surface from breathing should be avoided on a roof.
- It does not change the appearance: colourless, it hides neither a stain nor a faded shade.
- It cannot be combined with the algicide: the two products are not mixed, the roof receives one or the other.
Water-repellent treatment prices
| Service | Unit | Price excl. VAT |
|---|---|---|
| Roof moss removal and cleaning, treatment and gutters included | per m² of roof | €10 |
The treatment is not paid for separately, whether water repellent or algicide: its price is included in the moss removal price, €10 per m² of roof excl. VAT, whatever the roof covering. For 100 m² of roof, that makes 100 × €10 = €1,000 excl. VAT, treatment and gutter cleaning included. For work under €1,000 excl. VAT, travel and set-up costs are added; from that amount, they are not charged. All our prices: Roof moss removal prices.
Estimate your price in one minute
No obligation. Estimate shown excl. VAT.
Our jobs with water-repellent treatment
Beloeil · July 2024Moss removal and water repellent in Beloeil, July 2024
Chièvres · June 2024Moss removal and water repellent in Chièvres, June 2024
Enghien · June 2024Moss removal and water repellent in Enghien, June 2024
Woluwe-Saint-Pierre · May 2024Moss removal and water repellent on a slate roof in Woluwe-Saint-Pierre, May 2024
Frequently asked questions
Is the treatment (water repellent or algicide) included in the moss removal price?
Yes, always. Every Toiture Wash moss removal ends with a treatment, at no extra charge: depending on your roof, a colourless water repellent or an algicide, fungicide and bactericide product. Before comparing two quotes, check whether the treatment is included, and at what price.
Water repellent or algicide: who chooses?
The team, depending on your roof. They are two separate products that are never mixed: the water repellent waterproofs, the algicide, fungicide and bactericide product slows down moss regrowth. On a hard-wearing roof, it is generally the algicide.
How much does a water repellent cost for a 100 m² roof?
With us, nothing on top of the moss removal, since the treatment is included: 100 × €10 = €1,000 excl. VAT for 100 m² of roof, gutter cleaning included too. Full example: a 100 m² roof.
Does water repellent come in colour?
Not with us: our water-repellent treatment is always colourless. It protects without changing the look of the roof. For a revived or new colour, we offer roof painting.
What is the difference between a water repellent and a waterproofing product?
A water repellent makes water bead on the surface of the material without blocking its pores: water vapour can still escape. "Waterproofing" is used more broadly, including for products that form a film. On a roof, the aim is to repel rain without stopping the material from drying.
How long does a roof water repellent last?
It depends on the product, the surface and the exposure, and many manufacturers do not commit to a lifespan in years.
When should a roof be treated with water repellent?
Straight after a moss removal, when the roof covering is dry, in dry weather and when there is no frost. There is no point applying it to a roof still covered in moss: the product has to touch the material.
Can I apply a water repellent myself?
You can find some in DIY shops. The difficulty is not the product: it is working at height, getting the roof perfectly clean and dry, and applying the right amount. Our guide Removing moss from your roof yourself? details the risks.
Is a water repellent useful on slates?
It depends on the roof: the team chooses the treatment, water repellent or algicide product, and on a hard-wearing roof it is generally the algicide. In Woluwe-Saint-Pierre, in May 2024, slates without asbestos received a colourless water repellent after their moss removal.
Do you also apply water repellent to facades?
Yes: on a facade, the water repellent is part of the cleaning, and its price is in the price per m² of wall. See facade cleaning.