1. General Strategies for Preventing Condensation and Mould Growth

1.1 Control Indoor Humidity

Managing humidity is the first step in reducing condensation:

• Ideal indoor humidity: Keep it between 30–50% (use a hygrometer to monitor levels).
• Ventilation: Always use extractor fans in bathrooms, kitchens, and laundry rooms.
• Dehumidifiers: A good-quality dehumidifier helps remove excess moisture, especially in colder months.
• Mechanical Ventilation with Heat Recovery (MVHR): These systems offer a winning combination of comfort, health, and sustainability. They're a fantastic investment for any modern home, making life a little bit easier and a lot more pleasant! MVHR systems gently draw in fresh air from outside and filter it, removing dust, pollen, and other nasties. This fresh air is then warmed using the heat recovered from the stale air being extracted from your home. This means you're not wasting precious energy heating up the fresh air from scratch!

Recommended ventilation systems (UK):

• FLUXO® Single Room MVHR Unit – Quiet, energy-efficient, and excellent for UK homes.
• ARIA® Continuous Extract Fan Unit (DMEV) – Budget-friendly and effective ventilator for use in wet rooms such as kitchens, baths, shower rooms, toilets and utility rooms.
• RESPIRO® One – Whole House Mechanical Extract with Heat Recovery (MVHR). (Great for new build projects).

1.2 Improve Air Circulation

• Open windows for at least 20 minutes daily, even in winter, to allow fresh air to circulate and reduce moisture build-up.
• Keep curtains and blinds open during the day to avoid trapping moisture.
• Use extractor fans or a Mechanical Ventilation with Heat Recovery (MVHR) system to maintain a constant flow of fresh air.
• Consider using an air purifier to remove pollutants and allergens from the air, particularly in areas prone to condensation.

1.3 Enhance Window Insulation

• Upgrade to triple glazing to reduce the formation of condensation by minimising cold surfaces.
• Choose windows with Low-E coatings and warm-edge spacers for improved insulation and overall thermal performance.
• Consider adding wall insulation to improve the energy efficiency of your home and reduce heat loss, further minimising condensation risks.

1.4 Proper Installation & Sealing

Even the best windows won't prevent condensation if air leaks allow warm indoor air to meet cold surfaces. Here's how to identify and fix those pesky leaks:.

How to Identify Air Leaks:

• Feel for drafts: Run your hand around the window edges. Can you feel a breeze? That's a leak!
• Use a candle or incense stick: If the flame flickers near the window frame, you've found a leak.
• Inspect for damage: Look for cracked seals, peeling silicone, or gaps in the window frame.

How to Fix Air Leaks:

• Weatherstripping: Apply foam or rubber seals to close gaps.
• Resealing gaps: Use high-quality, low-expansion foam or silicone to fill gaps between the window and the structural opening. This ensures a long-lasting seal.
• Consider replacement: If the leaks are extensive or the windows are old, replacing them might be the most effective solution.

2. Regular Maintenance

Preventing mould means keeping surfaces dry and clean.

2.1 Wipe Away Condensation

• Use microfibre cloths or a window squeegee to remove moisture daily.
• Pingi Moisture Absorbers help with long-term moisture control.

2.2 Cleaning Window Frames & Sills

Condensation left unchecked leads to mould growth. Use mould-resistant cleaners:

• HG Mould Spray – A strong bleach-based solution for severe mould.
• Astonish Mould & Mildew Remover – UK-made, eco-friendly, and effective.
• White Vinegar (5–10% solution) – A natural, non-toxic mould killer.
• Bicarbonate of Soda Paste – Scrub window sills with this for a mild cleaning option.

Tip: After cleaning, apply anti-mould paint or sealant on wooden window sills for extra protection.

3. Regional Considerations

Condensation and mould are influenced by climate, so it's important to choose windows that are suited to your specific region.

3.1 Coastal Areas (High Humidity)

• Moisture control: Use dehumidifiers or Mechanical Ventilation with Heat Recovery (MVHR) systems to maintain good air quality and keep moisture levels low.
• Regular ventilation: Ventilate your property regularly to prevent the build-up of moisture.

3.2 Cold Climates (Higher Condensation Risk)

• Triple-glazed windows: Choose windows with three panes of glass and a low U-value to maximise insulation and reduce heat loss.
• Efficient ventilation: Install ventilation units, such as the Venti Fluxo, for controlled air circulation and moisture management.

3.3 Warm, Humid Climates

• Passive ventilation: Incorporate passive ventilation systems to encourage natural airflow and reduce humidity.
• UV-resistant coatings: Choose windows with UV-resistant coatings to minimise heat transfer and keep your home comfortable.

4. FAQ

Q1: Why does condensation form on my double-glazed windows?

Even with double glazing, condensation can still occur if the humidity levels inside your home are too high or if there isn't enough ventilation. To combat this, make sure your home has good airflow and consider using a dehumidifier to reduce the moisture in the air. For a more significant upgrade, you might consider replacing your double-glazed windows with high-performance triple-glazed windows from reputable brands like Internorm or Drutex.

Q2: How do I know if mould is growing around my windows?

• Black or green patches on the window frame or sill.
• Musty smell near the window.
• Peeling paint or warped wood (signs of moisture damage).

Q: Can mould around windows cause health issues?

Yes. Black mould (Stachybotrys chartarum) can trigger allergies, respiratory problems, and asthma. Immediate cleaning and prevention are crucial.

Q: Will replacing my windows completely stop condensation?

Not entirely. While new windows reduce condensation, proper humidity control and ventilation are still needed.

Q: Do trickle vents help with condensation?

Yes and No. Trickle vents offer passive ventilation, which can help to reduce condensation by allowing moisture to escape and fresh air to circulate. But there are downsides of traditional trickle vents. Closed vents can trap moisture, leading to condensation problems. Open vents, on the other hand, can create draughts. Also, traditional vents don't discriminate between fresh air and unwanted intrusions, like street noise or insects. A more controlled solution: whole-house or single-room Mechanical Ventilation with Heat Recovery (MVHR) system is a much better choice. These systems provide controlled ventilation, keeping your home fresh and comfortable without the drawbacks of traditional vents.

Q: Should I use a humidifier in winter?

Only if indoor humidity drops below 30%. Otherwise, a humidifier worsens condensation issues.

Final Thoughts

Preventing condensation and mould growth requires a multi-pronged approach, combining high-quality windows, effective ventilation, humidity control, and regular maintenance. By implementing these strategies, you can significantly reduce condensation, prevent mould growth, and extend the lifespan of your windows while improving indoor air quality and overall health.