Mould control

Your Guide to Lasting Mould Prevention

What is mould growth?

Mould growth is one of the most common and serious health hazards found in living spaces. When mould appears on building elements, it is rarely due to a single cause; rather, it can result from a combination of factors. High indoor humidity, low surface temperatures, moisture trapped within building materials, or even the specific properties of a substrate can all contribute to its spread. Generally, the likelihood of mould growth increases as the difference between indoor air temperature and the temperature of wall surfaces becomes greater. For this reason, thermal bridges are especially vulnerable, as these areas tend to have the coldest surfaces in a room. Once established, mould not only damages the structure but can also release spores that trigger allergies, respiratory problems, and other health concerns.

To effectively prevent mould formation, the guidelines for “hygienic minimum thermal protection” must be observed consistently throughout the space. This means ensuring that wall and surface temperatures do not fall below 12.6 °C and that the relative humidity along these surfaces remains below 70%. Maintaining proper ventilation, controlling indoor moisture levels, and eliminating cold spots are all essential steps in reducing the risk of mould growth and creating a healthier indoor environment.

🏠 How to Check for Cold Bridges in Your Home

Cold bridges (thermal bridges) are areas where heat escapes more easily, making walls colder and creating the perfect conditions for mould. Here’s a simple way to check for them:

✅ Step 1: Feel for Cold Spots

• On a cold day, slowly run your hand along exterior walls, especially near windows, doors, and corners.

• Pay attention to areas that feel noticeably colder than the rest of the wall.

✅ Step 2: Look for Signs of Damp or Mould

• Check walls and ceilings for dark patches, black spots, or discolouration.

• Focus on corners, around window frames, and behind furniture (where air circulation is poor).

✅ Step 3: Watch for Condensation

• Look at your windows and surrounding wall areas in the morning.

• If water droplets or dampness appear regularly, there may be a cold bridge nearby.

✅ Step 4: Compare Room Temperatures

• Move around your home and notice if some areas feel colder than others, even with heating on.

• Corners, ceiling edges, and floor junctions are common problem areas.

✅ Step 5: Use a Simple Thermometer (Optional)

• Place a thermometer against the wall surface (digital laser thermometers work well but aren’t essential).

• If the wall surface is much colder than the air temperature in the room, this is a sign of a cold bridge.

✅ Step 6: Check Behind Large Furniture

• Pull wardrobes, sofas, or cupboards slightly away from outside walls.

• These areas often trap cold air and can reveal mould growth you might not see otherwise.

⚡ Tip:If you find cold bridges, improve ventilation, keep furniture a little away from exterior walls, and use insulation or professional advice to fix recurring problem areas.

Immediate Action

When mould or algae is already visible, the first step is to treat the affected areas directly. This can be done by applying a mould, algae, or spore-killing spray (Remmers BFA) to stop further growth and reduce health risks. Surfaces should then be cleaned thoroughly to remove any remaining residues. While these treatments are effective in the short term, they only address the surface problem. Without tackling the root cause, mould and algae are likely to return once the conditions remain favourable.

Long-Term Prevention

For a lasting solution, the underlying causes of cold walls and high humidity must be addressed. Upgrading with insulating systems such as IQ-Therm 2.0 or breathable, insulating renders like lime-based warm render helps to raise wall surface temperatures and eliminate cold bridges. These materials allow the building to “breathe,” preventing trapped moisture while improving overall thermal performance. Combined with good ventilation and moisture control, these measures create a healthier, more durable living environment where mould and algae struggles to reappear.

Finishing Touch – Lasting Protection and Style

After treating surfaces and addressing insulation, applying the right paint provides the perfect finishing layer of protection. Breathable and mould-resistant paints not only help walls regulate moisture but also keep your home looking clean, bright, and inviting. High-quality options such as Classidur F-Therm, Remmers Color SL, Remmers Color SA Plus, Earthborn Clay Paint, and Secil Isovit Rev SP combine durability with natural breathability, ensuring long-term resistance to mould and algae. By completing the process with these specialist coatings, you create a safer, healthier living environment that also feels comfortable and looks beautifully finished.