Condensation on soft-touch windows:
why it appears and how to get rid of it

Soft windows have a nice feature: once you close them over the veranda, the space instantly ceases to feel like much of an outdoor space. The wind stays outside. Rain and snow, too. And then one morning, you step out onto the terrace and discover the clear windows are covered in thousands of tiny droplets. At that moment, a logical diagnosis arises: "The windows are fogging up. Something must have been done wrong."

Not necessarily. More often than not, soft-pane windows on the veranda work too well in this situation. They close off the openings, reducing natural air exchange, and the moist air inside now has nowhere to go. Then physics comes into play. As usual, it didn’t read the brochure.

Where does the water come from if the window doesn’t leak?

Condensation isn’t water that’s passed through the film. It was already inside the veranda, only in the form of water vapor. Air can hold a certain amount of moisture, with warm air holding more and cold air holding less. When warm, moist air comes into contact with a relatively cold surface, it cools. If the surface temperature falls below the dew point, some of the water vapor turns into droplets. This is why water appears on the inside of windows in winter or on cold autumn mornings.

The most common reason is people

Humans are generally quite humid creatures. We exhale water vapor. Add four people, hot food, a kettle, and a veranda enclosed on all sides, and the humidity increases significantly even without rain. So, a typical situation looks like this: the windows in an empty gazebo are transparent. Then guests arrive, turn on the heating, and after a while the film begins to fog up. It seems like the heater is to blame. In fact, it’s a combination of heat + humidity + a cold surface + insufficient air exchange. The heating simply made the situation more noticeable.

Why is condensation especially noticeable in autumn?

Autumn creates near-perfect conditions for it. It’s relatively warm during the day. In the evening, the temperature drops quickly. Inside the closed veranda, the air still remains warm and humid. The windowpane quickly cools along with the outside air. As a result, its temperature reaches the dew point. Droplets form. This is especially noticeable early in the morning. Therefore, the situation "yesterday everything was dry, this morning everything is fogged up" doesn’t necessarily mean a change in the window’s condition. The weather has changed.

And in winter?

In winter, the temperature difference can be even greater, especially if the veranda, covered with soft-sided windows, is heated. For example, it’s -10°C outside, but +15°C inside. People are sitting on the veranda, the electric heater is running, and the windows are completely closed. The inner surface of the transparent fabric remains significantly colder than the indoor air. Add high humidity, and you get practically ideal conditions for condensation. Therefore, the paradox of a winter veranda is as follows: the more successfully you protect it from cold outside air, the more important it is to properly ventilate it.

Solution #1: Ventilation

The most effective method is often the most cost-effective. Open some of the soft-sided windows or the designated entrance to create air circulation. It’s not necessary to leave the gazebo open for several hours. In cold weather, intensive, short-term ventilation is often more effective. Opening openings on different sides is especially helpful — this creates a cross-flow.

Sometimes 10 minutes of normal ventilation gives more results than several hours with one small gap.

Solution #2: Don’t seal the gazebo completely airtight unless necessary.

The desire is understandable. If you’re installing soft-close windows, you want to eliminate every millimeter of draft. But for a veranda, 100% airtightness isn’t always a plus, especially if the space is regularly used. It’s helpful to plan ahead for the ability to quickly open one opening, the top, the entrance, or both sides.

Then humidity can be controlled. A sealed, transparent cube provides excellent wind protection. But after a while, compelling arguments for ventilation begin to emerge.