Waking up to windows dripping with water is a frustratingly common winter ritual. While it’s tempting to blame the glass, windows are actually just acting as a diagnostic tool. Because glass is typically the coldest surface in a room, it is the first place invisible water vapor hits its “dew point” and transforms back into liquid.
If left ignored, that pooling water leads to warped frames, ruined curtains, and toxic black mold. Dealing with window condensation requires a two-pronged approach: stopping moisture at the source and managing your indoor climate.
1. Stop Moisture at the Source
An average household releases roughly 8 liters of moisture into the indoor air every single day just through normal living. To get condensation under control, you have to target the biggest moisture culprits.
- Ditch the Unflued Gas Heaters: Portable, unflued gas heaters release massive amounts of water vapor directly into the room as a byproduct of combustion. Switching to a heat pump, electric heater, or central heating is often the single most effective way to dry out a house.
- Contain Cooking and Bathing Steam: Always run your kitchen rangehood and bathroom extractor fans. Crucially, leave them running for 10 to 15 minutes after you finish cooking or showering to ensure all the residual damp air is cleared out.
- Never Dry Clothes Indoors on Racks: Hanging wet washing inside effectively dumps liters of water directly into your carpets and walls. Dry clothes outside, or ensure your clothes dryer is vented directly to the outdoors rather than recirculating into the room.
- Cover Pots While Cooking: A simple lid on a boiling pot keeps steam inside the cookware instead of sending it straight to your windows.
2. Master the Art of Ventilation
Newer homes are built to be highly airtight to save energy, which means moisture gets trapped inside. Older homes might be drafty, but those drafts rarely provide controlled fresh air where it’s actually needed.
Natural Cross-Ventilation
According to data from building research associations like BRANZ, opening your windows wide for just 10 to 15 minutes every morning can completely flush out stale, heavy air and dramatically drop indoor humidity. For the best results, open windows on opposite sides of the house to create a cross-draft.
Utilize Trickle Vents
If your window joinery is equipped with passive “trickle vents” or secure two-setting fasteners, keep them open. They allow a continuous, safe stream of fresh air to circulate without compromising your home’s security or letting in massive gusts of cold wind.
3. Raise the Temperature
Warm air acts like a sponge—the warmer it is, the more water vapor it can hold without dropping it onto surfaces as condensation.
Maintaining a consistent indoor temperature of at least 18°C drastically reduces the periods of high relative humidity that trigger window crying.
Pairing solid insulation (in the ceiling and underfloor) with effective heating ensures that your walls and window frames stay above the dew point.
4. Upgrade Your Glass and Joinery
If you have optimized your heating and ventilation but still struggle with dampness, the physical property of your windows may be the bottleneck.
| Window Feature | How It Fights Condensation |
| Double Glazing (with Low-E) | Standard single glass chills easily. Double glazing creates an insulating air gap, keeping the inner pane of glass much closer to the room’s temperature so moisture can’t condense on it. |
| Thermal Breaks | Standard aluminum frames conduct cold directly from the outside. Thermally broken aluminum or timber frames isolate the cold, preventing moisture from pooling on the joinery. |
The Morning-After Fix: Wipe it Down
While you work on long-term climate fixes, never let condensation sit. Use a window vacuum (like a Kärcher) or a microfibre cloth to wipe down wet glass every morning. If you have timber frames, keeping the paintwork in pristine condition is essential to prevent that pooling water from soaking into the wood and causing rot.