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Algae Growth - What Are The Different Stages On A Render Façade?


When it first became a popular building material, render was thought to be maintenance-free. Architects and property owners believed that, once applied, render wouldn’t discolour, require cleaning or change its appearance over the years.

However, now that many rendered buildings are beginning to age, we can see in discoloured facades that this isn’t the case. Over time, algae can begin to grow on rendered facades. As it spreads, algae will:

Understanding how and why algae grows, and how it can impact a render façade, will help property owners to properly maintain their buildings and ensure rendered façades look as good as possible.



What Causes Algae Growth?


Algae is a natural organism that grows on more or less all external surfaces. Over recent years, it’s become a lot more common to see algae growth on both domestic and commercial premises.

One of the main things that’s caused this increase in growth is the Clean Air Act. By reducing pollution, and making the air in our towns and cities cleaner, the act has caused an increase in airborne algae spores and therefore an increase in algae growth.

Our slowly warming climate has also had an impact on the growth of algae on external surfaces. In addition, poor detailing on the external rendered façades of buildings has also encouraged growth of algae. This is something that makes some properties a lot more prone to algae than others. 



Algae Colonisation on Rendered Surfaces

The first stage of algae growth is colonisation.  Algae are spread by the wind and thrive in moist, humid conditions. These spores will begin to grow as soon as they land on a suitable surface. Many types of algae find rendered buildings an ideal environment. The pores in the surface of the render give the algae something to hold onto while the moisture in the atmosphere allows it to thrive.


In general, surveyors find that buildings experience most algae growth on their northern facades. This is because the north face of property gets the least sun and so is more likely to remain damp.

However, properties that have poor drainage, or ongoing leaks, can experience high levels of algae growth in other areas. Once algae takes hold, it can quickly spread over the external surface of a building, especially during the wet, winter months. To prevent regrowth of the algae regular maintenance of the properties would be advised.


How Algae can Damage a Rendered Property


Red, green and black algae growth on a render won’t have a big impact on the core structure of a building and is unlikely to cause serious maintenance issues. However, it will have an effect on the aesthetic appearance of a property and can leave façades looking discoloured, tired and uncared for.

If left untreated, algae can spread to cover large areas of a rendered façade, significantly altering the look of a property, such as creating streaks on your roof. This can make a property look older than it should and can give residents and passersby the impression that the maintenance of the building is not up to scratch.


 Types of Algae that Grow on Rendered Facades


 There are three types of algae that commonly grow on rendered surfaces:

Green algae is the most common type and can often be removed with gentle washing. Red algae is common in Northern Ireland and Scotland and is something we’re seeing more in England as the climate becomes warmer and wetter. Black algae, though less common, is very difficult to remove and getting rid of it generally requires cleaning and the application of biocide.


Render Cleaning and Algae Removal 


 All types of modern rendered surfaces, including high-quality products from manufacturers including K-Rend and Weber Saint-Gobain, require regular cleaning to remove algae and prevent regrowth.

Our pioneering render care system allows property owners to restore the external walls to their original aesthetic appearance while preventing quick regrowth of algae.

Four Steps to Fully Refresh the Appearance of your Property


This staged process allows Spectrum to thoroughly remove the algae from the surface of a rendered building. On completion, properties that have undergone a thorough clean using the render cleaning product are restored to their original aesthetic appearance and are protected from future algae growth.


Why is our Unique 3D Printed Specialist Equipment Quick and Cost-Effective?


To help our operatives get to every corner of a building, and to keep access costs as low as possible, we design and 3D print our own specialist equipment. This allows our operatives to clean discoloured facades from ropes instead of cherry pickers and scaffolding, something that can dramatically reduce costs and ensure the algae clean is completed as quickly as possible.


Preventative Maintenance

Regularly removing algae from the surface of a rendered building helps to keep the façade looking as good as possible. What’s more, regular, preventative maintenance allows property owners to monitor the condition of their properties and address any issues that may be contributing to the rapid growth of algae. For example:


Find out more, and learn about the pioneering render façade cleaning services Spectrum offers in South London and surrounding areas, by exploring our site or getting in touch with a member of our team.


Back to Blog Posts

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