If you've started noticing black mould around your windows, you're certainly not alone.
In fact, it's one of the most common mould-related issues we investigate in homes across Stoke-on-Trent.
Many homeowners tell us:
👉 "The walls are fine, but mould keeps appearing around the windows."
Or:
👉 "I've cleaned it several times, but it always comes back around the frame."
The good news is that windows often provide some of the clearest clues about what's happening with moisture levels inside a property.
The mould isn't usually caused by the window itself.
Instead, it's often telling us something important about condensation, airflow, and humidity within the home.
🌫️ Mould Needs Moisture To Grow
Black mould cannot grow without moisture.
The question is:
👉 Why does moisture tend to collect around windows before anywhere else?
The answer usually comes down to surface temperature.
Windows are often the coldest surfaces in a room.
When warm moist air comes into contact with colder glass or frame materials:
👉 condensation forms.
Repeated condensation eventually creates the conditions mould needs to develop.
❄️ Windows Are Usually The Coldest Part Of The Room
Even modern double glazing is generally colder than:
- Internal walls
- Ceilings
- Floors
During colder weather, external temperatures cool the window surface much faster than surrounding areas.
This means windows often reach the condensation point before the rest of the room.
As a result:
✔ Water forms on the glass
✔ Moisture collects around frames
✔ Window reveals remain damp for longer
Over time, mould begins appearing.
🧱 Cold Bridging Around Window Reveals
One of the biggest contributors to mould around windows is cold bridging.
Cold bridging occurs when heat escapes through part of the building more rapidly than surrounding areas.
Around windows, this often affects:
- Window reveals
- Lintels
- Corners adjacent to frames
- Older installations
These areas become colder than the surrounding wall surface.
The colder the surface:
👉 the easier it is for condensation to form.
🌬️ Airflow Around Windows Is Often Restricted
Many homeowners don't realise how much airflow affects mould growth.
Window areas are frequently affected by:
- Closed curtains
- Blinds
- Furniture placement
- Deep window boards
These can reduce air circulation around the frame.
When airflow decreases:
- Surfaces remain colder
- Moisture evaporates more slowly
- Condensation lingers longer
This creates ideal conditions for mould growth.
🏠 Modern Homes Can Still Experience It
A common misconception is that condensation only affects older properties.
We regularly see mould around windows in:
- New-build homes
- Recently renovated properties
- Well-insulated houses
- Double-glazed homes
Why?
Because modern homes are often more airtight.
While this improves energy efficiency, it can also allow humidity levels to build up if ventilation isn't adequate.
💧 Everyday Activities Produce Huge Amounts Of Moisture
Most homeowners underestimate how much moisture is generated inside the average home.
Every day, water vapour is released through:
- Showering
- Cooking
- Drying clothes indoors
- Breathing overnight
- Washing and cleaning
A family can easily release several litres of moisture into the air every day.
If that moisture isn't removed:
👉 condensation becomes much more likely.
⚠️ Cleaning The Mould Doesn't Remove The Cause
One of the most common frustrations we hear is:
👉 "I've cleaned it several times and it keeps coming back."
That's because mould is usually a symptom rather than the cause.
Cleaning removes the visible growth.
But if:
- Humidity remains high
- Condensation continues forming
- Ventilation remains inadequate
the mould often returns.
The underlying moisture issue needs addressing.
🌡️ Why It Gets Worse During Winter
Many homeowners notice mould around windows worsening during colder months.
This happens because:
✔ Window surfaces become colder
✔ Indoor humidity often rises
✔ Windows remain closed more frequently
✔ Condensation forms more readily
This combination creates ideal mould-growing conditions.
🔍 How We Diagnose Window Mould Properly
At Weather Wise Solutions Limited, we investigate:
- Relative humidity levels
- Ventilation performance
- Surface temperatures
- Condensation patterns
- Airflow around windows
- Thermal bridging risks
Because the important question isn't:
👉 "How do we remove the mould?"
It's:
👉 "Why is moisture forming around this window in the first place?"
🛠️ How Window Mould Problems Are Fixed
Depending on the property, solutions may include:
- Improving ventilation
- Upgrading extractor fans
- Installing Positive Input Ventilation (PIV)
- Managing humidity levels
- Improving airflow around windows
- Addressing thermal bridging where practical
The aim is always:
👉 reduce condensation before mould has a chance to develop.
👨🔧 Signs Worth Watching For
If mould is appearing around windows, you may also notice:
✔ Condensation on glass
✔ Damp window reveals
✔ Musty smells
✔ Mould behind curtains
✔ Black staining around frames
✔ Water droplets on sills
These often indicate wider humidity and ventilation issues within the property.
📞 Need Help in Stoke-on-Trent?
If mould keeps appearing around your window frames, it's worth getting the issue assessed properly before it spreads further.
At Weather Wise Solutions Limited, we're a family-run damp company specialising in:
- Mould and condensation control
- Ventilation solutions
- Damp proofing
- Timber treatment
- Moisture diagnosis
We're also proud members of the Damp Proofing Association and the Federation of Damp, with CPD-qualified specialists in dampness in buildings.
👉 Book your free quote here: https://weatherwiseuk.co.uk/pages/contact
👉 Contact us today: https://weatherwiseuk.co.uk/pages/contact