Double Glazing Maintenance FAQ Sheet

Condensation build-up on glass units

It is important to note that condensation is not caused by a faulty glass unit. As warm air cools, it loses its capacity to hold moisture. As a result, condensation naturally occurs at the turn of the weather, when warm summer air cools as winter approaches. This moisture will gather as condensation on the coolest surface of a room in your house, usually on a window. Because warm air rises, you may find this commonly occurring in an upstairs bedroom, if your house has more than one storey.

There are a number of different solutions to this problem. Ventilating your house regularly in the morning time will remove this moist air from the house, preventing condensation build up. Turning up your heating in the affected rooms will also improve the situation, as the warmer air will hold more moisture, and prevent it gathering on cool surfaces.

Our Rehau PVC frames are designed to cope with condensation, and have a natural drainage system built into them. The PVC unit contains a channel that runs along the bottom of the frame, containing outlets allowing excess water to run out. It is also normal to find excess water still lying in the channel. It will evaporate naturally in time, and is not caused by a faulty unit.