Why sealed homes get damp

Air always contains moisture. When warm, moist indoor air meets a cold surface — an external wall, a window, the back of a wardrobe — it condenses into water. In a sealed home, that moisture has nowhere to go, so it settles into plaster, fabric and timber. Within weeks you get condensation, then mould, then that unmistakable musty smell.

Ventilation breaks this cycle by swapping humid indoor air for drier outdoor air. The trick is doing it correctly, especially in winter when you don't want to lose all your heat.

The right winter ventilation method

Cross-ventilate, don't just crack a window. Open windows on opposite sides of the home for 5–10 minutes to create a through-draft. This flushes out moist air quickly without cooling the walls themselves, so you lose very little heat.
Twice a day is the target. Morning and afternoon, ideally on dry, brighter spells.
Time it with the weather. Ventilate when the outside air is drier — mid-morning on a clear day is ideal. Avoid opening up during fog rolling off the lagoon or during heavy rain, when you'd let more moisture in than out.
Ventilate after moisture-producing activities — showering, cooking, drying anything indoors.
Keep interior doors open between airings so air can circulate into corners, hallways and closets where mould starts first.
Humidity targets to aim for

Keep relative humidity between 45% and 55%. A cheap hygrometer (under €15) in the main living area tells you instantly whether you have a problem. Above 60% consistently means you need more ventilation, a dehumidifier, or both.

The problem for owners who live abroad

Correct winter ventilation requires someone physically opening and closing windows twice a day — impossible if you're in the UK, Germany or Ireland for months. This is precisely why lagoon-side homes develop damp and musty smells over winter, no matter how good the owner's intentions.

At DryHome we build scheduled ventilation into every visit, combined with humidity monitoring and dehumidifier management, so your home breathes even while you're away. If your property is near the lagoon, we're happy to explain how a winter care schedule would work for it.