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Roof Cleaning – Everything You Need To Know

Roof Cleaning

Many homeowners in the UK will be familiar with the sight of moss & other unsightly growth on their roof tiles. This growth can be a real nuisance to prevent long-term, but what causes it & how can achieve a clean roof? In this article we are going to answer some of the most common questions regarding roof cleaning so you can find everything you need to know in one place.

What Causes Growth On Roof Tiles?

There are a number of types of unsightly growth on roof tiles which include:

  • Discolouration
  • Green growth & algae
  • Moss

The root cause of this growth is moisture, which is absorbed by roof tiles from rainfall. This is because the moisture absorbs into the roof tiles, creating the conditions that are perfect for moss & other natural growth to thrive.

This is contrary to what many believe, as a large proportion of homeowners do not realise how absorbent building materials such as roof tiles, brick & stone are.

Is Roof Cleaning Necessary?

Aside from the loss of aesthetic appeal that is caused by a weathered roof, there is a significant performance reason why roof cleaning is sometimes essential.

When moisture creates the conditions required for spores of moss to bloom on roof tiles, moss can compromise the ability for your roof to keep out moisture. If the moss is allowed to grow on your roof, the moss will fill the gaps between the roof tiles. Gradually over time, this moss can move & damage the roof tiles as it absorbs further moisture and expands, compromising the bond between the adjoining materials that ensure the integrity of the roof.

The moisture that is uptaken by the moss will also cause deterioration of the roof tiles, as moisture is the single biggest cause of damage to exterior building materials. Tiles can delaminate due to high moisture levels, plus in winter months, freeze thaw cycles can cause further movement of roof tiles.

Ultimately, moss & green growth is a key indicator of high moisture levels of your roof tiles, which if left over time could lead to enhanced deterioration.

Roof Cleaning

While pressure washing was a typically used method of roof cleaning, today dedicated cleaning companies & roof companies use a 'soft wash' method to clean roof tiles. This involves steaming the roof tiles rather than creating a high pressure water stream that dislodges the moss. This is less damaging than pressure washing, ensuring no disruption to the tiles during the cleaning process. 

While roof cleaning alone can remove large areas of moss growth from the tiles, it does not prevent the potential for further moss growth due to some spores that will remain on the roof. With high moisture levels, the conditions that caused the moss to grow in the first place are still present. Due to that, it is necessary to use a fungicidal cleaner that will kill any natural growth before it can bloom. 

Due to the technical nature of roof cleaning, it is not advised to clean it yourself, as you can cause further damage by taking it upon yourself to complete the project. We highly recommend getting in touch with a company that offers roof cleaning services, we have access to the right equipment & are experienced with using fungicidal treatments on the roof. 

As we have mentioned however, cleaning your roof is not the end of moss growth for good. New spores could make their way onto the roof, which can thrive in the high moisture conditions on your roof. For that reason, for long-term moss prevention, you must prevent this moisture.

Clean roof

Roof Waterproofing Treatments

Roof waterproofing treatments are products that create a waterproof barrier on the surface of roof tiles, stopping this transfer of moisture from the external environment into the tile. While there are many of these products on the market that refer to themselves as 'sealers', this is a term that should be treated with caution.

A sealer is a product that creates a waterproof seal on the surface of the material, that prevents any moisture from entering the material but also prevents any moisture from escaping. This can be terrible for the condition of your roof as moisture will simply continue to build up underneath the seal until either the treatment fails or the tiles becomes damaged, as the moisture attempts to escape.

This is why any waterproofing treatment for exterior surfaces must be 'breathable'. A breathable treatment is one that has an SD value of under 1, meaning that water vapour can freely travel through the surface, By maintaining breathability, water vapour to escape and maintains a dry material.

That is why we developed our ProPERLA super hydrophobic technology, which chemically bonds to building materials, lining the pores of the substrate without create a sealing film. While giving water repellent properties to materials, it maintains breathability as it allow water vapour to freely pass through the treatment. ProPERLA treatments have an SD value of 0.01-0.03, demonstrating exceptional breathability.

We developed this technology for a range of surfaces, including walls, paving, timber & roof tiles. For roof tiles in particular we offer ProPERLA Water Repellent, which is a completely invisible waterproofing treatment and RENOTEC Roof Coating, which is a coloured roof paint.

In independent tests conducted by UKAS accredited laboratory Lucideon, both RENOTEC Roof Coating & ProPERLA Water Repellent were found to perform for 25 years, ensuring their long-term ability to prevent water absorption and protect roof tiles from deterioration.

The other huge benefit of ProPERLA super hydrophobic technology is that it creates self-cleaning roof tiles. As water cannot attach itself to the roof tile due to the water repellent properties, dirt & other contaminants are simply washed away with any rainfall. This self-cleaning cycle helps to keep roofs looking pristine for years to come.

Cleaned roof with a roof coating applied

RENOTEC Roof Coating

ProPERLA Water Repellent (2)

ProPERLA Water Repellent

How Do I Treat My Roof With ProPERLA?

As the most advanced nano-technology available in the UK, ProPERLA is a specialised product that must be applied by experts.

We have a number of approved ProPERLA applicators up and down the UK who have attended our rigorous training program to ensure they apply the treatments to the highest level. To find an approved ProPERLA applicator, simply type your postcode in our applicator finder tool and find your nearest applicator, who can carry out the treatment for you.

Alternatively, if you are a roof cleaning company, why not become an approved applicator of ProPERLA super hydrophobic treatments & be able to offer your clients the most advanced exterior waterproofing technology in the UK?

water repellent

Water Repellent

A one-coat super hydrophobic advanced clear waterproofing coating that does not alter the appearance of roof tiles. Designed for all mineral substrates, including absorbent roof tiles. Comes with a manufacturers guarantee of 10 years.

  • Highly breathable system
  • Extends the lifespan of roof tiles by keeping them dry
  • Provides a self-cleaning, super hydrophobic surface
  • 25 year proven performance

RENOTEC Roof Coating

A two-coat super-hydrophobic coloured roof coating from ProPERLA's sister brand RENOTEC. It improves resistance to weather influences & extends the life span of the roof tiles, coming with a 25 year proven performance & a 10 year manufacturer's guarantee.

  • Highly breathable system
  • Extends the lifespan of roof tiles by keeping them dry
  • Provides a self-cleaning, super hydrophobic surface
  • 25 year proven performance

Frequently Asked Questions

Q. How do I become an approved applicator of ProPERLA products?

To ensure our products are only applied by trained experts, we ensure that applicators attend our training course in order to become an approved applicator of ProPERLA products. Why not read more about our training course if you would like to be able to offer ProPERLA technology to your clients.

Q. How do I find an approved applicator?

If you are a homeowner and are looking to have your roof treated with ProPERLA super hydrophobic treatments, you can find an approved applicator to apply the treatments on our approved applicator finder tool. Simply type in your postcode and find the details of an approved company in your area who are qualified to apply our products and can issue a manufacturer guarantee of 10 years on our behalf.

Our approved applicators commonly offer both roof cleaning & roof coating services, as the roof must be clean to able to apply ProPERLA products. For this reason, you are getting both roof cleaning & long-term protection in one service.


Want to speak to one of our technical advisers for further advice on roof cleaning? Send them an email to info@properla.co.uk & one of the team will be on hand to assist you with any questions you may have.


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