Finding moisture on your windows every morning is more than just a nuisance – it’s a sign that your home’s “breathing” balance is off. Whether you have condensation inside double glazed windows or persistent fogging on single panes, understanding the cause is the first step to a drier, healthier home.
What is Condensation and Why Does it Form?
In simple terms, condensation occurs when warm, moisture-heavy air meets a cold surface (like a window pane). The air cools rapidly and can no longer hold the water vapor, which turns into liquid droplets.
The temperature at which this happens is called the Dew Point.
The Rule of Thumb: The colder your window glass, the more likely you are to see condensation. This is why single glazing suffers the most, while triple glazing stays largely clear.
1. Condensation on the Inside (Room Side)
This is the most common type of window condensation. It is rarely a fault with the window itself; rather, it is a symptom of high humidity and poor ventilation.
Common Causes:
Lifestyle: Drying clothes on radiators, boiling kettles, and hot showers.
Poor Airflow: Modern homes are “airtight,” which traps moisture inside.
Inadequate Heating: Cold rooms allow surfaces to drop below the dew point faster.
The “Quick Fix” Checklist:
The 5-Minute Blast: Open windows on opposite sides of the house for 10 minutes daily to flush out moist air.
Use Trickle Vents: If your windows have them, keep them open 24/7.
Close Kitchen/Bathroom Doors: Prevent steam from traveling to colder bedrooms.
2. Condensation Between the Panes
If you see moisture inside double glazed windows that you cannot wipe away, the window has “failed.”
Why has this happened?
Double and triple-glazed units are hermetically sealed. Over time, the seals can perish due to age or poor installation. Once the seal breaks:
The insulating Argon gas escapes.
The desiccant (the material inside the spacer bar that absorbs moisture) becomes saturated.
Moisture enters the gap and fogs up the glass.
The Solution: Unfortunately, “failed” units cannot be repaired by cleaning. The glass unit must be replaced to restore energy efficiency and clarity.
3. Condensation on the Outside
Surprisingly, seeing condensation on the outside of your windows is actually a good sign! It typically happens on high-performance triple glazed windows.
It means your windows are so thermally efficient that no heat from your home is escaping through the glass to warm up the outer pane. It will usually evaporate as soon as the sun comes up.
Does Triple Glazing Reduce Condensation?
Yes, significantly. Because triple glazing features three layers of glass and two gas-filled cavities, the internal pane stays much warmer than standard double glazing.
By upgrading to energy-efficient windows, you raise the surface temperature of the glass above the “dew point,” effectively stopping condensation from forming in all but the most humid conditions.
Stop the Damp: When to Call the Professionals
If you have tried improving ventilation but still face excessive condensation on windows, it might be time for an upgrade. Persistent moisture leads to black mould, which can damage your health and your window frames.
At Select Windows, we help homeowners in the West Midlands find the right glazing solutions to eliminate damp and improve warmth.