Single panes are cold and secondary glazing can trap damp air between two sheets. Work out which you have, and what to rule out before you spend money.
Water on single glazing is condensation: warm, moist indoor air meeting the coldest surface in the room. Secondary glazing can cut that, but if damp air gets into the gap or the original window is sealed shut, it can mist up between the sheets. Start by reducing moisture, keeping a steady low heat and using the vents you have. A dehumidifier helps with the air, but it does not fix a leaking frame or a failed seal.
Streaming water or droplets on an old single pane, wet sills, black spots on the frame or sealant, or a film of mist on the room-side or between the original window and a secondary pane fitted inside it.
Winchester City Council describes condensation as damp that comes from extra moisture in the air inside your home: when that air touches a cold surface, such as windows, ceramic tiles or pipework, it turns to water. Single glazing is simply the most obvious cold surface. If the water is on the outside of the glass, or the frame is wet from a leak, that is a different problem.
Nothing about single or secondary glazing is unique to Ashford, and we have not verified a local statistic, so we will not invent one. What matters locally is the age and type of your windows. If your home is listed or in a conservation area, check with Ashford Borough Council before changing windows.
A dehumidifier lowers the moisture in the air. It does not repair a failed seal, a cracked frame or a leaking reveal, and it does not replace a missing secondary pane. If the mist is sealed between two panes of a double-glazed unit, the unit has failed and needs replacing. If you rent, report window defects to your landlord in writing; a Dryzen system is not suitable for rentals unless the landlord authorises the changes.
A Dryzen system is a loft-mounted dehumidifier with insulated ductwork to the central area or stairway of the home. Each unit is rated for 150 square metres and has an extraction rate of 12 litres a day, and it uses about 20 pounds a year in energy. It suits owner-occupied homes with a loft where the cause is condensation. A free survey can tell you honestly whether a system would help, or whether the windows need attention first.
Cotswold District Council advises that single glazed windows should not be draught-proofed when secondary glazing is added, to reduce the chances of moisture and mould between the window and the secondary glazing. Check the advice for your own window with the installer.
Condensation forms where moist indoor air meets a cold surface. A single pane is usually the coldest surface in the room, so it shows the problem first. Reducing indoor moisture and keeping the room steadily warm both help.
Not by itself. A window manufacturer's advice page says the inner pane of a double-glazed unit is warmer than the outer pane, which helps stop condensation forming on it, but moisture can still collect on other cold spots if the air stays damp.
Sources: Cotswold District Council: Windows (retrofit and energy efficiency); Winchester City Council: Condensation, damp and mould; Castle Point Borough Council: Condensation advice; GOV.UK: Understanding and addressing the health risks of damp and mould in the home; Anglian Home: How to stop damp in your conservatory
Last reviewed 2026-10-15. General guidance only; this is not a survey of your home.