Moss and algae are best removed by gentle brushing and manual cleaning, never with a pressure washer on roof tiles. The cost depends on surface area, degree of fouling, roof type and accessibility. You receive a free, no-obligation quote in advance, often after a brief roof inspection.
Why is moss on your roof a problem?
Moss and algae do more than make a roof look neglected; over time they actively damage it. Moss traps moisture against your roof tiles or roof covering. In frost that moisture expands and can flake off the top layer of clay or concrete tiles (frost damage). The roots also work their way between and under the tiles, giving water an easier route inside.
A bigger practical concern is blockage. Loosened clumps of moss wash into your gutters and downpipes with the rain. Once those clog, water overflows or pools on the roof, raising the risk of a roof leak. A clean roof simply lasts longer. You can read more in our article on the lifespan of a roof.
How do you remove moss and algae from a roof?
We always work from gentle to thorough, so the roof covering stays intact. The approach varies by roof type.
Manual removal and brushing (the safe method)
On pitched, tiled roofs we remove moss by hand and with a soft brush, often on an extension handle. It is more labour-intensive, but by far the safest method: the protective top layer of the tiles stays intact. Afterwards we can apply a biodegradable anti-algae treatment that lets remaining algae and spores break down naturally.
Why not use a pressure washer on roof tiles?
A pressure washer looks fast and thorough, but on roof tiles it is often harmful. The hard jet damages the factory top layer or glaze. The result is a more porous surface that fouls again faster and harder, and absorbs more moisture as well. We therefore advise against pressure washing tiles. On robust flat roofs in bitumen or EPDM, low-pressure or steam cleaning can sometimes be safe, provided the seams and edges are undamaged.
| Method | Suitable for | Effect on roof |
|---|---|---|
| Manual + brushing | Roof tiles (clay/concrete) | Safe, preserves the top layer |
| Anti-algae treatment | Tiles and flat roofs | Tackles spores, prevents return |
| Low-pressure / steam | Flat roofs (bitumen/EPDM) | Safe if seams stay intact |
| High-pressure | Strongly discouraged on tiles | Damages top layer, faster re-fouling |
What determines the cost of roof cleaning?
We can only quote an honest figure once we have seen your roof, because no two roofs are alike. That is why we do not publish rates, but we are happy to explain which factors set the price:
- Surface area of the roof: more square metres means more work.
- Degree of fouling: a thin film clears faster than a thick layer of moss built up over years.
- Roof type: brushing tiles by hand takes more time than cleaning a smooth flat roof.
- Accessibility: is scaffolding, a cherry picker or a roof anchor needed to work safely?
- Pitch and height: a steep or tall roof requires more precaution and time.
- Additional work: cleaning the gutters too, or an anti-algae aftertreatment.
The only honest way to know the cost is a tailored quote. With us that is always free and without obligation, often preceded by a short inspection so you know exactly what will happen.
Combine cleaning with inspection and maintenance
When we are up on your roof anyway, it is a logical and cost-effective moment to look further. During a roof inspection we check for cracked tiles, loose ridge tiles, damaged roof covering and corroded lead or zinc work. Minor defects we spot can often be handled straight away as a roof repair, before they grow into a leak. That way you avoid paying twice to set up scaffolding.
How do you stop moss from coming back?
Staying completely moss-free on a Dutch roof is hard, but you can slow the growth considerably. Keep gutters clean and clear, prune overhanging branches that cast shade and hold moisture, and schedule periodic maintenance instead of waiting until the roof turns green. An anti-algae aftertreatment keeps the roof clean for longer. North-facing and shaded roofs need a little more attention than sunny sides.
Ready for a clean, healthy roof?
At Dakservice van Belzen you are never just a number. Brothers Tonnie, Jos and Noah are happy to come by for a free, no-obligation quote and will check at the same time whether anything else needs attention. You get a reply within 2 hours via WhatsApp, and our roof work comes with up to 15 years of warranty. Feel free to contact us and we will schedule a visit quickly.
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Frequently asked questions
That depends on your situation. A north-facing roof or one shaded by trees fouls faster than a sunny roof. As a guideline, many roofs stay in good shape for several years after a thorough cleaning, provided the gutters stay clear. A periodic roof inspection shows when action is sensible.
Both. Moss holds moisture, can damage the top layer of tiles in frost, and its roots work under the tiles. Loosened clumps also wash into the gutters, which can cause blockages and eventually leaks. Cleaning in good time extends the lifespan of your roof.
On roof tiles we strongly advise against it. The hard jet damages the protective top layer, making the roof more porous so it fouls again faster. Working on a roof without proper fall protection is also dangerous. Have cleaning done safely and professionally instead.
We can only quote a firm price after seeing your roof. The cost depends on surface area, degree of fouling, roof type and accessibility (scaffolding or a cherry picker). You always receive a free, no-obligation tailored quote, often after a short inspection so you know exactly what is needed.