Window and frame mould cleaning

Window mould cleaning for frames, seals, sills and reveals in UK homes, with typical costs and practical steps to cut condensation at windows.

In short: Window and frame mould cleaning removes mould from uPVC, timber and aluminium frames, rubber seals, sills and the plastered reveals around windows where condensation collects. It suits homes with streaming windows in winter and black spotting around the glass. In the UK it typically costs around £40 to £80 per window, or £150 to £350 for a whole house.

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Windows are usually the coldest surface in a room, so they are where indoor moisture condenses first. Water runs down the glass, sits in the bottom of the frame and soaks the seals, sill and the plaster reveal beside the window. Over a winter that is enough for black mould to spread through the rubber gaskets, into the corners of the frame and up the reveals. Older double glazing, single glazing, secondary glazing and windows set in thin or uninsulated walls tend to suffer most.

Cleaning a window properly means more than wiping the glass. The frame, the drainage channels in the bottom of uPVC frames, the rubber gaskets, the sill and the reveals all need cleaning and treating. Gaskets that are permanently stained can often be replaced, and timber frames may need sanding and repainting. Blocked frame drainage and closed trickle vents are common contributors, so they are cleared and checked, and you are given practical advice on keeping condensation down so the windows stay clean.

What is included

Fungicidal cleaning of window frames, sashes, beads and handles
Cleaning and treatment of rubber seals and gaskets around the glass
Clearing of drainage slots and channels in uPVC frames
Cleaning and treating the plaster reveals and window board or sill
Cleaning and checking trickle vents so they open and close freely
Advice on replacing permanently stained gaskets or failed sealed units
Treatment of mould on curtains tracks and blinds fixings where reachable

Who it is for

Windows that stream with condensation on cold mornings
Black mould in rubber seals or in the corners of uPVC frames
Mouldy plaster reveals and window boards beside the glass
Older homes with single glazing, secondary glazing or early double glazing
Bedrooms where windows are kept shut overnight

How much does it cost?

As a guide, window mould cleaning typically costs around £40 to £80 per window, or roughly £150 to £350 for all the windows in a typical house. Replacement gaskets, failed sealed units and repainting reveals are priced separately. See our full cost guide.

How it works

Inspect each window

We note which windows are affected, the frame type, the condition of seals and vents, and whether any sealed units have failed and are misting between the panes.

Clean frames and seals

Frames, beads, gaskets and drainage channels are cleaned with a fungicidal treatment suitable for uPVC, timber or aluminium.

Treat the reveals

Plastered reveals and sills are cleaned and treated, and left ready for anti-mould paint if the finish is stained.

Prevention steps

Trickle vents are checked and you are given simple steps to reduce condensation at the glass, such as morning wiping, airing and steady heating.

Window and frame mould cleaning: FAQs

Why do my windows get so much condensation?

Warm indoor air holds moisture from cooking, washing, drying clothes and breathing. When it touches cold glass it cools below its dew point and the moisture turns to water. Bedrooms with closed windows, rooms that are heated only occasionally, and older glazing with poor thermal performance get the worst of it. Condensation on the inside of the glass is a ventilation and moisture issue rather than a fault with the window.

Can mould in window seals be cleaned?

Surface mould on the rubber gaskets usually cleans off, but where black staining has gone into the rubber it often remains as a mark even after treatment. Many gaskets on uPVC windows can be pulled out and replaced with new ones at modest cost, which is often the quickest way to make the window look clean again.

Are trickle vents worth keeping open?

Yes. Trickle vents provide a small, constant flow of fresh air that helps carry moisture out of the room, and they are designed to be left open. Approved Document F expects background ventilation in habitable rooms, and replacement windows in England generally should not reduce the ventilation that was there before. Keeping vents open in winter makes very little difference to heating bills compared with the condensation it prevents.

Should I replace my windows to stop mould?

Not as a first step. New, better insulated glazing reduces condensation on the glass, but if the moisture in the home stays the same it can move to the next coldest surface, such as wall corners. Deal with ventilation and moisture sources first. Replacing windows makes most sense where frames are rotten, sealed units have failed or the glazing is single and draughty.