Why moss, lichen & algae damage roofs

Your roof is the first defence barrier against weather conditions, protecting your property from wind, rain and UV light. If you don’t look after roofing, hidden leaks can cause significant and costly issues like wet and dry rot. However, are you aware that moss growth on your roof also poses a threat?

Moss, lichen and algae can be just as destructive as the elements. While these organic growths may appear harmless or provide a rustic appearance, there could be real damage going on beneath if you leave them untreated.

Here’s why moss, lichen and algae are bad for your roof.

Why are moss and algae bad for your roof?

Moss and algae often thrive on rooftops because they like damp and shaded hosts, especially if you have lots of trees or poor drainage across your roofing. Unfortunately, moss retains moisture much like a sponge does, especially in the areas between tiles, preventing the roof from drying out properly. It can also increase weight across the entire structure, weakening roof materials.

Issues with mossy roofs include tile lifting, rotting underlayers and leaks, shortening your roofing’s lifespan. On the other hand, algae growth appears as black streaks, which can degrade tiles and reduce your home’s curb appeal.

What is lichen?

Lichen is a mixture of algae and fungi that appears as crusty, patchy growths. Lichen on roofs is often green, grey or blueish in colour, clinging tightly to roofing surfaces. Unlike moss or algae alone, lichen growth can root deeply into the tiles and form a bond that’s impossible to remove without damaging the materials underneath.

What does lichen do to your roof?

Lichen is one of the most damaging growths to appear on UK roofs, burrowing deeply into roofing tiles to weaken them and cause granule surface losses. As time goes on, lichen growth can inhibit a roof’s ability to reflect UV light, leading to even faster deterioration. In the colder months of the year, lichen absorbs moisture, which can freeze and expand within existing small cracks. If you spot lichen on your roofing, get it checked out before a total roof replacement or extensive repairs are required.

How do I get rid of moss and algae from my roof?

Removing moss, algae or lichen from roofing requires careful attention. This will often involve a soft washing process with low-pressure washers and eco-safe solutions to kill off spores and prevent regrowth. If growth is widespread, we’d highly recommend a professional roofing inspection to assess the damage and provide targeted cleaning or repair work. Signs your roof is damaged include visible green and black growths, tile cracks, water stains in your loft or attic, and granule build-ups in gutters.

Get a free roof inspection in London and Surrey

Contact Collier Roofing today for free roof inspections in Kingswood, Lingfield and beyond. To speak to our expert roofing contractors, get in touch now.