Why does moss grow on roofs?

Moss finds roofs an ideal place to thrive, as they provide a cool, damp and shaded environment. Furthermore, moss is able to resist drought, frost and temperature extremes - making it suitable for surviving even the toughest roofing conditions. It doesn't require soil either; as long as there's moisture and nutrients present, it can attach directly to the roof's surface.

However, although many people look at moss as only a visual problem which detracts from their home's appearance and value, it can be much more serious than that. Moss growth on roofs can cause considerable structural damage, costing thousands of pounds to repair in the worst-case scenarios. So why does moss grow when some homes seem more prone to it? All roofs can be vulnerable to moss growth, but tiled roofs are particularly susceptible. Left unattended, it can cause extensive long-term problems: not only does it detract from the aesthetic of your house, but it may also damage the structure and clog up your home's drainage system.

What is moss?


Moss is an umbrella term referring to a variety of non-vascular plants that grow vigorously in moist conditions. These hardy species are among the most robust and quickly multiplying plants, able to colonise and spread rapidly over a roof in just days. Though it may appear similar to garden weeds, moss can be more intrusive, withstanding climates that weeds cannot. It is this tenacity that makes moss a nuisance for many homeowners. Furthermore, the water absorbed by its leaves can freeze in colder temperatures and potentially crack roof tiles, leading to costly damage to properties.  For these reasons, it is important to take steps to remove or prevent moss from taking hold on your roof.

How does moss get on my roof?


Moss spores are the source of moss growth on a roof. These microscopic reproductive cells can travel to your roof through the wind, birds, or other animals like squirrels. As they settle in the crevices between tiles, they form a spongy green carpet over your roof. Areas that are damp and receive little direct sunlight are ideal environments for moss to grow and thrive. North-facing roofs surrounded by trees and exposed to lots of rain are especially prone to moss growth, with both clay and concrete tiles being particularly vulnerable due to their porous surfaces that allow spores to take root quickly. It is therefore essential to be mindful of keeping moss at bay.

Is moss bad for roofs?

Moss on a roof can cause significant harm in the long run. Its roots can penetrate small crevices in the tiles, potentially resulting in water seeping and causing further destruction. Furthermore, it encourages moisture accumulation, leading to rot or other structural issues - especially during winter when freezing and thawing increases - expanding and contracting with temperature changes. Moreover, moss can block rainwater from properly draining off the roof, causing water to pool and damage the surface even more. Finally, it traps dirt and debris, potentially leading to the development of algae and lichen.

How can I prevent moss growing on my roof?

The most effective way to prevent moss from growing on a roof is to keep the environment around it as dry as possible. This can be accomplished by trimming back trees and shrubs near the house, ensuring that gutters and downspouts are in good condition and well-maintained, and making sure there are no areas where water can pool and stagnate. Additionally, it's a good idea to clean the roof regularly—especially in shady areas and around chimneys, vents, and other places where debris collects—and inspect for signs of moss growth.

How can I clean the moss from my roof?

A job best left to the professionals! Cleaning your roof yourself is an endeavour that may not be worth the risk. DIY roof cleaning can involve working at heights and using chemicals, which must be handled with caution to avoid harm to those doing the job. Additionally, walking on a wet and slippery surface has the potential of causing serious injury or, in severe cases, death due to trips, slips and falls. Professional roof cleaning services are the preferred method as they possess the correct safety equipment and expertise to do the job quickly, safely and efficiently. So if you want a clean roof without putting yourself in danger, it is best to hire a professional roof cleaning service.

How do professionals clean roofs?

Specialised roof cleaners have the right knowledge, equipment and experience to successfully clean your roof. They know how to operate safely while working at heights, making sure that there is no risk of harm or damage to your property. These professionals are trained in removing moss, algae, soot, and lichen build-up from any kind of roof. Their tools are designed to access hard-to-reach areas, ensuring a comprehensive clean. Moreover, many specialist companies even provide warranties for their services - reflecting the confidence they have in their ability to achieve great results. The cleaning would typically involve scraping away moss with specialised tools followed by soft washing and an application of biocide to prevent future growth. This will help keep your roof looking clean and pristine for years to come.

How often should roofs be cleaned?

A biocide treatment can be applied to the roof after it has been thoroughly cleaned in order to prevent moss and other growth. This treatment should effectively keep the roof free of any further growth for a period of 3-5 years, under normal urban conditions. In rural areas, this period could be shorter. To extend that time frame however, regular maintenance treatments can be done to ensure the roof remains in good condition and lasts longer.

To conclude

Moss grows on roofs for several reasons and is a common problem in the UK. Most commonly, it is the result of a combination of moisture, shade, and warm temperatures. Moisture from rain or condensation encourages moss growth on roofs because it provides an ideal environment for the moss to thrive in. Shade also plays a role by blocking direct sunlight and keeping the roof cool, which moss prefers. Warm temperatures also help the moss grow by providing it with the necessary environment for photosynthesis and growth.

Moss needs to be removed from roofs for several reasons. Moss absorbs moisture and can cause water damage or leaks if left unchecked. It can also obstruct water flow off of the roof, leading to ice dams and other issues. Moss can also trap debris and cause superficial damage to roofing materials, such as tiles. Finally, moss growth can contribute to the formation of mould or mildew, which can cause health problems for people living in a home with a mossy roof. For all these reasons, it is important to remove moss from roofs and keep them clean and clear.

Looking for a professional roof cleaning service in Manchester?

AM Property Services is a trustworthy and experienced provider of roof cleaning services in Manchester. Our team are dedicated to providing high quality results, using the latest techniques to leave your property looking its best. With years of experience in the industry, we know what it takes to keep roofs clean and well maintained for maximum longevity. From moss removal and cleaning gutters to repairs and restoration, we have the necessary skills to get the job done right. We use eco-friendly products and methods that are safe for your property, family, and pets. With our competitive rates and friendly customer service, you can rest assured that your roof will be professionally cleaned in no time. Your satisfaction is our top priority – let us show you why we’re the best choice for roof cleaning in Manchester. Contact us today to get started.