How Do You Clean a Roof Window?

Check how your window opens

Roof windows vary, so begin with the type. A centre-pivot window turns on a horizontal axis at the middle of the sash, and on many models the sash can be rotated through half a turn and locked, so the outside pane faces into the room. A top-hung window opens outward from the top and gives limited reach to the outer face. Some have a cleaning mode that holds the sash at a safe angle. Look for the handle and a catch or a small lever that lets the sash rotate. If you are unsure, the maker's instructions will show it, and our overview of roof window types explains how the main styles operate.

On a fixed window or a flat rooflight there is no sash to rotate. The inside can be cleaned as normal, and the outside needs a long-handled tool from a safe position or a professional visit.

What to use

Warm water with a drop of washing-up liquid does almost everything. Apply it with a soft sponge or microfibre cloth, working from the top down so dirty water runs over uncleaned glass. Rinse with clean water if you can, and dry with a squeegee or a lint-free cloth to avoid streaks. For stubborn deposits, such as bird droppings or tree sap, soak the area first with a damp cloth rather than scrubbing dry grit across the surface.

Some roof windows have a self-cleaning coating that breaks down dirt in daylight and lets rain wash it away. It works best on a steep slope and in rain, and it can be damaged by abrasive pads and harsh cleaners. If your window has one, follow the maker's guidance, and be sparing with detergent, since too much leaves a film.

What to avoid

Do not use scouring powder, wire wool or a scraper on the glass, as they scratch it, and do not use ammonia or bleach on coated surfaces or seals. A pressure washer is a bad idea: it drives water past the seals, strips coatings and can damage the flashing. Avoid spraying cleaning fluid on the rubber seals or the timber frame. Do not lean on the sash or force it past its stop, because the hinges and the balance springs are not meant to bear body weight.

Above all, do not go onto the roof. Tiles and slates break underfoot, the surface is slippery when damp or mossy and a fall from a roof is a serious injury. If the outside cannot be reached from within, use a telescopic pole with a squeegee head from the ground or a ladder placed against the wall, or hire a window cleaner who has the equipment to work safely at height.

Seals, frames and the channels around

While you are there, wipe the rubber seals with a damp cloth to remove grit that can stop them closing tightly. Check the frame for damp patches or flaking paint. Look at the gap around the outside of the window where leaves and moss gather, and clear it by hand or with a soft brush from a safe position. A build-up of debris holds water against the flashing and can lead to a leak, so a quick look is worthwhile every few months.

Inside, condensation on the glass is a different matter from dirt. If the pane runs with moisture in cold weather, the room needs more ventilation, and the guide on condensation on roof windows explains the causes. Wipe it away, because standing moisture marks the timber and rots the frame over time.

Blinds and screens

If the window has an inner blind, check how it is fixed before you clean near it. Pleated and roller blinds often run in side channels, and water splashed into them leaves marks and can corrode the fittings. Pull the blind fully down or up, depending on the type, wipe the glass with a barely damp cloth near the edges and let it dry before the blind is moved. Dust the blind fabric with a soft brush or a vacuum on a low setting, and follow the maker's cleaning advice for the material. An external blind or shutter can be wiped with the same mild soap solution.

How often

Twice a year suits most windows, in spring and autumn. A window under trees, near a busy road or in a spot attractive to birds needs cleaning more often. Keep the maintenance light and regular, so dirt never has a chance to harden.

When to call someone

If misting appears between the panes, the sealed unit has failed, and cleaning will not fix it. If water stains show on the lining or the sash does not close firmly, the seals or flashing need attention, and the page on leaking roof windows covers what to look for. We can check the window as part of a roof visit, photograph the flashing and the frame from the roof, and tell you if anything needs doing, free of charge at the survey stage. Our other roof glazing advice is gathered on roof windows and skylights.