Algae on the facade: removal of red algae and green growth

Microorganisms such as fungi or algae on the facade not only look unattractive, but also damage the building fabric / the ETICS. In addition, mosses can also grow on the house wall, store water and thus cause mould in the long term.

In addition, energy efficiency decreases with damp walls, as the wetness draws heat energy out of the wall to evaporate and thus cools it down.

Whether fungi, mosses, red algae or other infestations – the solution for your house clearly consists of removing the algae and other growth, followed by disinfection and sealing.

The facade sealing should also be carried out as a precautionary measure for new or renovated buildings.

New facades: Sealing the surface

In the case of new facades or masonry, you should take direct precautions and seal the surface (have it sealed). Depending on the dedicated construction or maintenance company, the experts have a good idea and the right products for facade sealing.

These are available in various colours as well as in transparent versions. Details of the facade paint from proPERLA®, which protects the facade from the effects of the weather (sun, acid rain, salt fog, smog, etc.) and repels moisture from rain and fog, can be found on our homepage.

In summary, thanks to our sealants and paints, you provide the facade of your house with breathable, water-resistant and self-cleaning agents that add value to properties.

Algae infestation on the facade: What to do against algae?

The most effective way to combat algae is in sunny weather or in summer when temperatures are high. In addition to green algae, brown or red algae are often found on house walls, which should first be removed with a high-pressure cleaner.

Particularly in the case of red algae that root deeper into the wall, experts use a special cleaning agent that does not damage the facade, but removes the red algae deep down – deep into the pores. After cleaning, the house facade / masonry usually needs to dry first.

It is then treated with disinfection. In future, the disinfectant will not only stop red algae and green algae, but also other microorganisms such as bacteria, mosses, lichens and fungi.

Cleaning, disinfecting – and don’t forget the sealing

The first two steps are often praised as sufficient by many professionals who do not want to use three steps.

For a few years, the house facade / masonry may also look good and be protected by the disinfection. However, the effect of the disinfectant will eventually fade, so that unsightly and harmful microorganisms will find a nesting area again.

Therefore the sealing, as described above, should not be forgotten. Only when the facade, wall or similar external surfaces are sealed will they withstand the weather and remain noticeably cleaner and free of mosses, lichens, fungi and algae for longer. This is also beneficial for the durability of the external thermal insulation composite system (ETICS).

How do algae form on the facade?

Algae on the facade is an indication of clean air, but also an indication of permanently damp surfaces and thus of energy-inefficient facades.

Although thermally insulated walls are often so well insulated that the moisture does not evaporate due to the retention of heat – the heat that gets through over time is immediately consumed by the wet wall. Ergo, a dry wall is absolute necessary for modern houses and facades.

It would also deprive algae, as well as other organisms, plants and infestations, of their habitat. This is because water is the main reason for algae to form on the facade.

These are the most common conditions in which the algae (green, red, brown, etc.) can thrive:

  • Permanent moisture / wetness
  • Light, preferably the sun
  • Carbon dioxide from the air
  • Mineral materials from plaster / facade
  • Temperatures from 0°C to 40°C

Where does infestation occur most frequently?

Walls, brickwork and facades are particularly quickly and frequently infested with green algae, red algae, mosses, lichens and other organisms if they point to the north but still receive sufficient (reflected) light.

This is because north-facing walls dry out badly or completely – they simply do not get enough sunlight.

Only in summer, when high temperatures, little precipitation and warm winds come together, is there a chance for these walls to dry out. But most green and red algae survive this time.

This is why cleaning, disinfection and sealing are so important to permanently prevent algae infestation. Especially sealing with special products is essential to repel new moisture.

Steps against algae infestation in the summary

The algae infestation of facades or masonry is unattractive and also harmful to the building substance. Therefore the algae should be removed from the facades.

The same applies to fungi, lichens and mosses, which can also and above all form on good thermal insulation, but on permanently wet surfaces. These steps (best carried out by experts) will help you against algae infestation:

  1. Facade cleaning to remove the algae
  2. Disinfection of the surface for deep, long protection
  3. Sealing with proPERLA® for permanent dryness

Our offers: Ideal for new construction and renovation

Our products for the facade as well as for the floor and roof are ideal if you are building a new house or renovating a purchased house. We offer an attractive and effective solution for different surfaces, floors, walls and roofs.

In this way you protect your property against weather, moisture and harmful infestations. Feel free to browse through our site and get an idea of our facade colours, roof colours, the horizontal barrier for walls that get wet from below and much more.

Besides proPERLA® we also offer solutions from thermaSOL®, RENOTEC®, COROSAN® and more.

Our promise

Our various systems for the optimal treatment of the exterior surfaces of your house have optimal properties for long-lasting weather protection, for maintaining air circulation and other advantages. As already mentioned on the products page, this is our promise:

The unique composition of a proPERLA® treatment transforms your house facade into a self-cleaning surface, extremely water-repellent but always breathable. Thanks to the microporous properties of proPERLA® façade paint, your façade remains fully breathable and ensures good air circulation, which benefits a pleasant climate in your home.


Whether renovation or new construction, you should not neglect the facade. Algae on the facade can become a real problem.

That is why you should take care as early as possible with special facade paints and sealants for long-lasting protection against water and microorganisms. Protect your facade surface!

Featured photo from:

Logo Properla 300px

proPERLA® offers a range of exterior super hydrophobic waterproof paints & coatings designed to reduce energy costs and protect homes.

Through our official network of applicators, we provide services to end customers, ensuring the correct application of our products for your benefit.

Whether you are a professional interested in working with our products, or a customer looking for solutions, contact us for more information.

Share this post
Latest from the blog