The red algae invasion: How microorganisms destroy your flat roof – and how Pur-protect stops the infestation!
- Jul 25
- 3 min read
Updated: Aug 3
Anyone who notices reddish or brownish discoloration on their flat roof is often dealing with a biological survival artist: Red algae. Once these organisms have damaged the roof membrane, costly consequential damage is likely.
Red algae: A growing problem
This problem is becoming increasingly serious: Due to noticeable climate change - in particular milder winters, longer periods of wet weather and warmer summers - red algae are spreading rapidly in our latitudes. Optimal protection is therefore more important than ever. But how can an acute algae infection on a flat roof be prevented and the building protected in the long term?
Three key measures to prevent red algae growth on flat roofs in the long term
Consistently avoid backwater (prevent puddle formation)
Clean the roof mechanically regularly with high-pressure water and a broom
Select suitable roof renovation products such as the Pur-Protect system
Climate change as a catalyst for red algae on flat roofs
Red algae on roofs used to be a rare exception. Today, roofers and experts are observing this phenomenon everywhere. The reason lies in climate change: Higher average temperatures combined with heavy rainfall create a warm, humid microclimate on flat roofs. Because red algae possess an extremely resistant, gel-like protective layer, they can withstand even intense UV radiation in the summer and multiply even faster when moisture is subsequently added. Conventional building materials often can no longer cope with these new biological stresses.
Combat the causes: moisture and red algae from the Flachdach entfernen
Red algae require constant moisture to grow. Therefore, the best protection is a functioning drainage system. For new buildings, a sufficient slope can easily be integrated into the planning. Even if a roof is being renovated, the existing slope should be optimized so that rainwater can drain away quickly.
When you spot the first spots of red algae during regular inspections, you can remove them as long as they have not yet caused significant damage to the surface. In the early stages, the biomass can easily be completely removed with water and a brush.
When does professional flat roof renovation become unavoidable?
If algae have already made the material porous, only a complete renovation will do. A high-quality roof coating against red algae has proven to be an extremely effective method. The use of modern liquid plastic with fully reinforced fabric is particularly efficient. This process ensures a seamless roof seal and has a crucial advantage: its ease of application makes it ideal for DIY flat roof renovations for homeowners with good DIY skills.
However, when choosing materials, the crucial question of long-term resistance to biological attack should always be addressed.
The Pur-Protect advantage: Lasting protection thanks to PURelastik liquid plastic
To prevent the growth of moss and algae on roofs, many manufacturers rely on standardized chemical additives (algicides). The problem in practice: Suppliers of these additives often don't provide specific information about the exact quantities needed for genuine, climate-resistant, long-term protection.
This is where Pur-Protect roof renovation sets new standards. The liquid plastic used (PURelastik from ISOPOL) is based on years of internal testing. ISOPOL has developed a highly effective, precisely dosed combination of substances.
The result is a perfectly algicidal roof coating that, as a highly UV-resistant liquid plastic, withstands extreme weather conditions. Those who want to rely on positive experiences with Pur-Protect will find a system here that permanently deprives red algae and other microorganisms of their breeding ground – despite advancing climate change. Further technical details and information about the material can be found directly at www.pur-protect.de.
Conclusion
Progressive climate change is forcing us to rethink building protection. Red algae are no longer just an aesthetic problem, but a real threat to the structural integrity of modern flat roofs. Standard renovations with imprecise amounts of active ingredients often fail to adequately combat these resilient organisms.
The Pur-Protect system proves that effective protection is possible. Thanks to its long-established, precise dosage of active protective agents, the PUR*elastik* liquid plastic blocks algae growth directly on the surface. Anyone who wants to seal their flat roof long-term, seamlessly, and with absolute climate resistance—whether as a professional contractor or using a do-it-yourself approach—will find the ideal solution for today's and tomorrow's challenges in this innovative technology.
Red algae or a brittle roof membrane?
Before the next heavy rain causes costly damage: We seamlessly renovate your flat roof with highly elastic liquid plastic – without expensive demolition work!
