It's one of the questions we hear most often: is roof cleaning actually worth it, or is it just cosmetic? The honest answer is that it depends on what's growing on your roof — but for most homes across Dorset, Somerset, Wiltshire and Hampshire where moss, algae and lichen have taken hold, the answer is yes.
Why moss and algae are more than a cosmetic problem
Moss acts like a sponge on your roof. It traps moisture against the tile surface and holds it there long after the rain has stopped. In winter, that moisture freezes and thaws repeatedly, gradually lifting and cracking tile edges and pointing. Left long enough, that damage shortens the life of the roof and leads to leaks into the timbers beneath.
Algae and lichen do similar work on a smaller scale — they root into the tile surface and slowly degrade the protective coating on concrete tiles. So a roof that looks "just a bit green" is often quietly deteriorating.
What safe roof cleaning achieves
Done properly, roof cleaning removes the moss, algae and lichen that are actively damaging your tiles, and treats the spores at the root so the growth doesn't simply return within months. The result is a roof that looks better, drains properly, and is no longer holding water against the tile surface.
The key word is properly. High-pressure jet washing will strip moss away in seconds — but it will also strip the protective granular coating from concrete tiles, force water under the tiles and into the felt membrane, and dislodge ridge pointing. That's the fastest route to an expensive re-roof, not a solution.
When is it genuinely worth it?
Roof cleaning is worth it when:
- There's visible moss, algae or lichen growth holding moisture on the tiles.
- You want to protect the roof's lifespan rather than wait for frost damage.
- You're maintaining a property's value or preparing it for sale.
- You want the roof to stay cleaner for years, not months, with a biocidal treatment.
It may not be worth it where the tiles are already severely degraded or the roof is nearing the end of its life — in those cases we'll tell you honestly, because cleaning won't restore a coating that has already worn away.
Watch the short answer
In this short video, we answer the question directly — is it worth cleaning your roof, and what does a proper clean actually achieve?
The Clearstone approach
We clean roofs using a controlled low-pressure wash — hot or cold, depending on the tile type and the level of growth — followed by a gentle biocidal softwash that kills growth at the root. Every roof clean comes with our 2-year organic growth guarantee, with an optional 5-year warranty that requires discounted follow-up softwash treatments in Years 3 and 5 to stay active.
If you're unsure whether your roof is worth cleaning, the best first step is a free roof survey. We'll assess the tile type, the level of growth, and whether cleaning is safe — and we'll tell you honestly if it isn't.
Related questions
Get your free roof cleaning quote or call us on 01747 413013.
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