Black mould growth on a residential wall in Sheffield. Close-up of black mould and condensation on a wall. Visible mould damage on a wall, a common problem in Barnsley homes.

Mould Season in the UK: What You Need to Know

While mould spores are present year-round, the "mould season" when mould growth becomes a significant issue for many UK homes is typically from autumn to spring, roughly September to April. This is when we start to see the perfect conditions for mould to thrive.

Why the Colder Months are Prime Time for Mould

  • Increased Condensation: As the temperature drops, we tend to keep our windows closed and our heating on. This traps moisture-laden air inside. When this warm, damp air comes into contact with cold surfaces like windows and external walls, it turns into condensation. This provides the moisture that mould needs to grow.

  • Less Ventilation: To conserve heat, we reduce ventilation by keeping windows and doors shut. This prevents the escape of moisture from daily activities like cooking, showering, and drying laundry, creating a humid environment that mould loves.

Key Facts About Mould

  • Mould is a type of fungus: It reproduces by releasing tiny, lightweight spores into the air. These spores are everywhere, both indoors and outdoors.

  • Mould needs three things to grow: A food source (almost any organic material like wood, paper, or fabric), a comfortable temperature, and, most importantly, moisture.

  • Mould can impact your health: Exposure to mould can cause a variety of symptoms, including allergic reactions, respiratory problems, and skin irritation.

Simple Steps to Prevent Mould

  • Ventilate Your Home: Open windows for a few minutes each day to let out stale, moist air. Use extractor fans in kitchens and bathrooms, and keep internal doors closed when you are cooking or showering to contain moisture.

  • Control Moisture: Use lids on pans when cooking and dry clothes outside whenever possible. If you must dry clothes indoors, do so in a well-ventilated room with the door closed.

  • Wipe Away Condensation: Make a habit of wiping condensation off windows and sills every morning. This simple step removes a key source of moisture that mould uses to grow.

  • Maintain a Consistent Temperature: Keeping your home at a low, consistent background temperature is more effective and often more affordable than turning the heating on and off in bursts. This helps prevent cold spots where condensation can form.

  • Allow Air Circulation: Don't push furniture right up against external walls. Leave a small gap to allow air to circulate and prevent moisture build-up behind it.