Lichen on tiles

Should lichen be removed from roof tiles?

Lichen is a crusty growth that grips the tile, and removing it is a judgement. Below: how it differs from moss, when to act, and how it comes off.

The short answer

Not always, because lichen on its own is not a reason to act. It is worth removing when it spreads over a large part of a slope, grows into gutters and valleys, covers a tile you suspect is cracked, or simply spoils the look of the roof. Lichen grips tight, so it is treated and brushed with care, never scraped off hard. We look at what is under it before deciding.

5 min read · Part of Roof cleaning

A hipped red-tile roof on a white-rendered bungalow — Pale crusty lichen patches on concrete roof tiles

How lichen differs from moss

Moss is soft and green, and it lifts away in cushions. Lichen is flat, crusty and often pale grey, orange or yellow, and it sits tight against the surface of the tile as if it were part of it. That difference shapes the treatment, because lichen does not come off with a light brush the way moss does.

It also behaves differently over time. Lichen spreads slowly in rings and patches across a slope, and it can sit on a tile for a long period without much visible change. A patch that is not growing and not near a gutter or valley is a different case from one that has spread across a whole slope in a short time.

Telling them apart matters for the quote as well. The tools and time for lichen are different from those for moss, and the written price reflects what is actually on your roof.

Neither growth is a sign by itself of a failing roof, and neither tells you much about the tile beneath. They are both growths on the surface, and both need a look at the tile once they are off.

When removal is worth doing

Taking lichen off is a judgement about the roof, and these are the points we weigh.

Lichen: leave it or act
What we see	Our usual advice
Small patches on sound tiles	Can stay for now
Spread across a slope	Worth treating
Over a cracked or slipped tile	Act, after a check
In valleys or near gutters	Clear it

Appearance is a fair reason too. Some owners simply want a roof that looks clean, and that is a perfectly good basis for a quote. We would only say that the surface of the tile matters more than the speed of the job, so the method is chosen with that in mind.

Colour can mislead. A pale patch might be lichen, dried moss or a stain, and only a close look from a ladder tells them apart. If you are weighing it up from the ground, photograph the patch in daylight, note which slope it is on, and send it over. We would rather look at a photograph first than book a visit that is not needed, and a close-up shows the texture that tells the growths apart.

How lichen is taken off

Lichen grips the tile, so scraping it dry is the wrong approach, since a scraper that bites into the tile leaves a rough patch that holds growth more readily afterwards. Jet washing can damage slate or tile, as Marley warns, so a powerful jet is out as well.

The method that works is gentler and takes longer:

Loose growth is brushed away lightly, without scraping the face
A biocide is sprayed at low pressure, so the lichen is treated where it sits
The roof is left for the product to work, following its label
Any remaining crust is brushed off lightly, tile by tile

Because the treatment needs time, lichen may not look different on the day of the clean. The roof clears over the following weeks as the growth dies back, and we explain that at the time so you are not expecting an instant result. Our answer on the roof biocide treatment describes the spray.

Patience is part of the method. Rushing lichen by hard brushing marks the tile, and the mark holds growth later, so a slow and gentle treatment protects the surface and gives a cleaner result over time.

Checking the tile under the crust

Once the lichen has been treated and brushed off, the tile underneath is checked, and that is where the useful information is. A hairline crack or a flaking corner can hide under a crust, and a survey shows it. We report each find with a photo and say whether it is a repair.

Streaks, moss and lichen often share a roof, and our answer on black streaks on a roof covers the dark film that appears alongside it. The wider job is on the main roof cleaning and moss removal page.

If you are unsure whether your patches are lichen or something else, share a photo, and we will give you our view on what it is and whether it needs a visit. If it does, the survey is followed by one written total, with the gutters cleared at the end.

Gutters are the last stop. Lichen and moss that have been brushed off land in them, so they are cleared by hand once the roof is done. A short look along the eaves at the end shows whether anything has slipped or cracked while the growth was coming off, and you get that in the photos too.