Moss, Algae or Lichen? What's Growing on Your Barnstaple Roof

Not all the green and grey on a roof is the same thing. In damp North Devon, a Barnstaple roof can play host to three different organisms at once: moss, algae and lichen. They look different, behave differently and cause different kinds of trouble, and knowing which is which helps you understand what your roof actually needs.

This guide walks through the three main types of roof growth, how to tell them apart from the ground, and what each one means for your tiles. None of it requires a ladder, just a little knowledge and a look up at the roof.

The quick answer: Moss is the thick, green, cushiony growth, algae shows as dark streaks or a green tinge, and lichen appears as flat, crusty patches. All three thrive in Barnstaple's damp air, and all are best removed with a gentle soft wash.

1. Moss: the thick green cushions

Moss is the most obvious of the three. It grows into raised, spongy, bright green clumps, usually starting in the gaps between tiles and on the shaded, north facing slopes where the damp lingers longest. In Barnstaple's wet climate it can build into a thick carpet surprisingly quickly.

It is also the most damaging. Moss acts like a sponge, holding water directly against the tiles and keeping them permanently wet. That trapped moisture works into joints and, in frosty weather, expands as it freezes, cracking tiles and widening gaps.

Because moss stands proud of the surface, it is the growth most likely to break away in clumps and slide into the gutters, where it causes the blockages that lead to overflow and damp.

2. Algae: the dark streaks and stains

Algae is flatter and less obvious than moss, showing up as dark green, grey or almost black streaks running down the roof, or as a general green tinge across the tiles. It is often mistaken for dirt or general weathering, but it is a living growth.

While algae does not hold water the way moss does, it still keeps the surface damp and signals that conditions are right for more growth to follow. Left alone, an algae covered roof tends to develop moss and lichen too, so the streaks are often the first warning.

Algae also dulls the whole look of a roof, spreading a tired grey green film across the tiles that makes even a sound roof look neglected. It responds very well to a biocide treatment, which kills it at the surface and slows its return.

3. Lichen: the flat, crusty patches

Lichen is the most stubborn of the three. It appears as flat, crusty patches, often pale grey, white or yellowish green, bonded tightly to the surface of the tile. Unlike moss, it does not brush away, because it grips the tile firmly and can even etch into the surface over time.

It thrives in clean, damp air, which the estuary environment around Barnstaple provides in abundance. Lichen is slow growing but persistent, and its tight grip makes it the hardest growth to shift by hand.

This is one reason a biocide based soft wash is so useful. Rather than trying to scrape lichen off, which risks damaging the tile, the treatment kills it in place and lets it weather away gradually and safely.

4. Why all three thrive in Barnstaple

The reason a Barnstaple roof so often carries all three is simple: the local climate suits every one of them. The damp estuary air, high rainfall and shade from the region's greenery keep roofs moist, and moisture is the common requirement for moss, algae and lichen alike.

Roofs on shaded, north facing slopes or under trees are worst affected, staying damp longest. Here is how to tell the three apart at a glance:

• Moss is raised, green and cushiony, standing proud of the tiles.
• Algae is flat, showing as dark streaks or a green grey film.
• Lichen is crusty and patchy, pale grey or yellowish, and firmly stuck down.
• All three favour shaded, damp slopes over sunny, exposed ones.
• Mixed growth is common, with moss, algae and lichen sharing the same roof.

5. Why the treatment is the same for all three

Although the three organisms differ, the right response is the same. A professional soft wash uses low pressure water and a biocide that kills moss, algae and lichen at the root, whatever the mix on your roof. There is no need to identify and treat each one separately.

The biocide is the key. Because it keeps working on the surface for months after the clean, it deals with all three types of growth and slows their return in Barnstaple's damp conditions. Scraping or blasting, by contrast, only removes what is visible and can damage the tiles.

That is why the gentle method suits every kind of roof growth here, clearing the current problem and giving lasting protection against the next.

6. Getting it dealt with safely

Whatever is growing on your roof, tackling it at height yourself is not worth the risk, particularly in Barnstaple's exposed, windy conditions. A professional has the access equipment to work safely and the knowledge to treat the growth properly without harming the tiles.

A proper clean also comes with a check of the roof and gutters, catching any slipped tiles or blockages while the growth is being dealt with. That combination keeps the whole roof healthy, not just clean.

Frequently Asked Questions

How do I tell moss from lichen?
Moss is raised, green and cushiony and brushes away fairly easily. Lichen is flat, crusty and pale, and grips the tile tightly so it will not brush off. Both thrive in Barnstaple's damp air.

Are dark streaks on my roof dangerous?
Those are algae. While less damaging than moss, they show the surface is damp and support further growth, and they dull the roof's appearance. They respond well to a biocide treatment.

Is lichen harder to remove than moss?
Yes. Lichen bonds tightly to the tile and does not brush off. A biocide soft wash kills it in place and lets it weather away, which is safer than trying to scrape it.

Do I need different treatments for each type?
No. A single soft wash with a biocide deals with moss, algae and lichen together, whatever the mix on your roof, and slows the return of all three.

Why does my roof have all three?
Barnstaple's damp estuary climate suits every type of growth, so mixed colonies are common, especially on shaded, north facing slopes that stay wet longest.

Not sure what's growing on your Barnstaple roof?
Ben's Roof Cleaning treats moss, algae and lichen across Barnstaple and North Devon, with over 15 years of experience and a gentle soft washing method. Get in touch or call 01271 441210 for a free, no-obligation quote.

Know your roof, protect your home

Moss, algae and lichen each tell a slightly different story, but on a Barnstaple roof they usually appear together, all encouraged by the same damp estuary air. Learning to recognise them helps you understand what your roof is dealing with, and the reassuring part is that the answer is the same for all three. A gentle soft wash kills the lot at the root and keeps working to slow their return, leaving your roof clean, clear and protected against whatever the North Devon climate sends its way.