Why do I need to keep my roof clean?

roof cleaningDoes a roof need to be beautiful? If all its slates are present and correct, does it matter what a roof looks like? So,  why do I need to keep my roof clean?

In fact, keeping your roof clean is an essential part of your general house maintenance and our roof cleaning wash and refurbish is one of Improve A Roof’s most popular services.

It’s not just about kerb appeal. A dirty roof can harbour all sorts of nasties and give you serious trouble down the line.

The main culprits that can spoil the appearance of your roof are algae, lichen, moss and collections of organic matter. The problems that they cause are not just cosmetic. 

Let’s take a look at these one by one, to better understand what they are and the issues they can cause for your roof.


There is an urban myth that dark stains on a roof are caused by airplane fuel jettisoned as planes fly over. In fact, these stains are usually caused by algae called Gloeocapsa Magma. 

Algae spores are carried by the wind and on the feathers of birds. Over time these hardy algae can grow to cover a large area of your roof. Algae thrive in shady areas and humid conditions. 

A favourite place is under overhanging tree branches, which provide shelter and dappled sunshine. Gloeocapsa Magma thrives on roofs as it feeds off asphalt and limestone, which are commonly found in roofing materials. In the long term, this will lead to a degradation of the fabric of your roof.


Lichen is not a single organism but rather a composite that results from algae and fungi developing together in a mutually beneficial relationship. Up to 8% of the Earth’s surface is covered in lichen and it is likely that you have some on your roof as it thrives on all surfaces. 

Lichen absorbs a large amount of water and can survive even when the water it is carrying freezes in winter. The various components of your roof will eventually be damaged by the constant presence of a quantity of water upon it, and wooden areas could begin to warp.


Moss shares lichen’s sponge-like ability for retaining water, but it also has a root system that can penetrate under slates and eventually loosen them. The clumps of moss on your roof may also prevent rainwater from running off the roof and direct it into areas that drain inefficiently. 

Moss will spread into your gutters, eventually blocking them and causing them to overflow.  

Organic matter

Leaves can collect on your roof in gullies and anywhere there are corners on a complicated roofline. Organic matter will block water egress, find its way into your gutters and provide a growth medium for any plant seeds that blow onto your roof – all causing potential damage if left unattended.

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Prevention is always better than cure. Our regular cleaning and inspection service will help keep your roof free from algae, moss, lichen, and environmental debris. 

Contact us 

We provide roof cleaning services in Lancashire, Yorkshire, Cheshire, Manchester, Merseyside, North Wales, Derbyshire, Shropshire, and Staffordshire.

Improve a Roof will provide you with an entirely free and no-obligation roof cleaning quotation.

We also offer complementary services to enhance your home further.

Call us NOW on: 0800 046 9686


About Us

We are a family run business offering Thermal Roof Coating and Roof Cleaning. We are based in Hazel Grove, Stockport and we have more than 30 years experience in the home improvement industry.

Improvearoof LLP

Contact us

Improve A Roof
97 Macclesfield Road
Hazel Grove
Stockport SK7 6DT
Open Mon – Sun 8am – 8pm

Freephone: 08000 469686

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