The short answer
Use warm water, a small amount of mild washing-up liquid and a soft cloth or sponge. Rinse with clean water and dry the glass with a squeegee or microfibre cloth. Clear the channel at the head of the unit of leaves and grit, and wipe the dark frame gently. Skip abrasive pads, solvents and jet washers, which mark the finish and push water into the seals.
Start with the safest way to reach it
A conservation rooflight sits flush in a pitched roof, often at a steep angle. Getting to the glass safely matters more than the cleaning itself.
Wherever you can, clean from inside first. The inner face is the one you see every day, and it needs nothing more than a cloth. For the outer face, a roof that is reachable from a first floor window or a low extension is one thing, and a slope that can only be reached by standing on tiles is another. Tiles and slates are slippery when damp, and old ones can crack under a foot. Do not step on the roof covering.
A pole with a soft brush head or a water-fed pole can reach the glass from the ground or a stable ladder. Hire a window cleaner with roof access equipment if the slope is high. Conservation rooflights are made to be glazed in place and are not designed to bear a person, so never lean on the glass. If you are after a unit that can take foot traffic, that is a different product, described on our walk-on rooflight installation page.
A routine for the glass
The glass needs very little. Most marks are dust, pollen, bird droppings and the film left by rain drying on the surface.
- Loosen the dirt. Wet the glass with clean water from a hose set to a gentle flow, or from a bucket. Let it sit for a minute so dried deposits soften.
- Wash. Use a bucket of warm water with a few drops of mild washing-up liquid. Work from the top down with a soft sponge or cloth, in light strokes.
- Rinse well. Soap left on glass dries into streaks and draws dust. Rinse until the water runs clear.
- Dry. A squeegee, drawn top to bottom and wiped at each pass, leaves no marks. A clean microfibre cloth does the same job on smaller panes.
Some units carry a self-cleaning coating on the outer pane. It works by letting rain spread into a sheet and carry dirt away, and it still benefits from an occasional rinse in a dry spell. Use only the same gentle method, because abrasion harms a coating. Our answer on whether conservation rooflights are double glazed explains what sits behind the outer pane.
Frame and gutter
The dark frame is what makes a conservation rooflight look right on an old roof. The finish is thin, so it rewards a light hand.
Steel and aluminium frames are normally finished in a durable dark coating, black or a deep grey. Wipe them with the same soapy water and a soft cloth, then dry them. If you wash the frame and leave it wet, water sits in the joints. Dry it. A little care once or twice a year keeps the finish even for the life of the unit. The notes on steel or aluminium conservation rooflights cover how the two metals age.
Many units have a small channel or drip at the head, where the glass meets the roof covering above it. Leaves, moss spores and grit gather there. Clear it by hand or with a soft brush, working downhill so the debris falls away from the frame. Check the tile or slate edges at the sides while you are there, and look at the roof covering from the ground with binoculars if you cannot safely see it. Anything more than loose debris is worth flagging to a roofer before the next downpour.
What to avoid
A handful of habits do lasting harm to a finish that is meant to last decades.
| Avoid | Why |
|---|---|
| Abrasive pads or scourers | They scratch glass and dull coatings |
| Bleach, acids or solvents | They attack the frame finish and the seals |
| Jet washers | They force water past the seals and strip paint |
| Razor blades on glass | They score the surface and the coating |
| Scraping off moss | It marks the glass and finish; use a brush |
Hard water leaves a chalky film on glass in Sussex, and the answer is to dry the pane rather than use a stronger product. A squeegee removes the water before it leaves a mark.
How often, and what cleaning will not fix
Twice a year suits most homes. The spring clean removes winter grime, and an autumn one clears leaves before the wet weather.
Trees change that rhythm. A rooflight under an oak collects more debris than one on an open slope. Cleaning keeps a unit looking and performing as it should, but it will not change how the room sounds. If rain drums on the glass or aircraft are loud in the loft, the cause is the glazing build, and the answer is the specification in the quiet spec. See quieter glazing for conservation rooflights for the options.
Cleaning also cannot clear a pane that has misted between the two layers. That moisture is inside the sealed unit, out of reach of a cloth, and the answer is a new unit. Our misted and failed rooflight replacement page explains how that works. You can get a quote once you know which units you have.
Cleaning questions, answered
Can I use a glass cleaning spray?
A gentle household glass cleaner is fine on the glass. Keep it off the frame, and do not use anything on a self-cleaning coating beyond what the maker states. Plain water with a drop of washing-up liquid is the safest default.
Why does my rooflight look dirty again within days?
Low pitches hold water and dust. A steep slope sheds both, but a shallow one lets a film dry on the glass. Drying the pane after each wash helps. The page on what roof pitch a conservation rooflight needs explains how pitch affects the glass.
Does condensation on the inside mean it needs cleaning?
Not usually. Condensation on the room side is moisture in the air meeting cool glass. Wipe it off and ventilate the room. See whether conservation rooflights get condensation.
Should I wash a blind fitted inside the unit?
Follow the blind maker's instructions, and dust it with a soft cloth. The page on fitting a blind to a conservation rooflight covers the options, and the main conservation rooflight installation page links the rest.