Why nobody walks on the roof
A conservatory roof looks flat and sturdy from the garden, but glass panes and twin-wall polycarbonate sheet are made to keep the weather out, not to carry a person. A foot placed on the wrong spot can crack a pane or crush the sheet, and the fall that follows is through the roof as well as off it.
That is why the cleaning is planned from the edges. A ladder at the eaves, a small tower beside the frame or a long-reach brush on a pole puts the work within arm's length without any weight on the glazing. Where the ridge sits too far from the edge to reach, a roofer may use a proper roof ladder or crawling board spread across the structure, but a householder should not improvise with a plank.
The same caution covers the house wall above. Many conservatories butt up against a first-floor wall, and the roof cannot be reached from the ground without a ladder footed on soft garden soil or a patio. Ask for the access to be set up properly, with the ladder tied or footed, before anyone starts brushing.
If the work cannot be done safely from the edges, it is better left until it can be.
Gentle methods for glass and polycarbonate
Green film, lichen spots and bird mess come off a conservatory roof with patience rather than force. Work through it in this order:
- Brush loose leaves, twigs and dried moss from the gutter edge and the glazing bars with a soft broom.
- Wet the whole roof with clean water so that grit does not scratch as the brush passes over it.
- Apply a mild cleaner made for glazing, in the strength on its label, and give it time to work.
- Brush gently along the slope with a soft head, never across the glazing bars with a stiff one.
- Rinse from the top down until the water runs clear.
A jet at high pressure is the wrong tool here. It can lift the rubber or silicone seal along a bar and push water into the gap between panes, which is how a roof that was only grubby starts to drip. Polycarbonate also scratches more easily than glass, and abrasive pads leave marks that catch dirt.
Polycarbonate roofs have a limited life. HomeBuilding gives a typical lifespan of 10 years, and The Eco Experts says about 10 to 15 years, so a sheet that is yellowed and brittle may be past cleaning.
Gutters at the same time
The gutter on a conservatory is often small, and leaf litter blocks it quickly when the roof sits under a tree. When a gutter overflows, the water runs down the glazing bars and the frame, and it can look like a leaking roof when the roof itself is sound.
Clearing it while the cleaner is already at the eaves makes sense for three reasons:
- the gutter holds the dirt that the roof wash is about to rinse into it;
- a blocked outlet shows up as standing water, which is easier to spot with the roof wet;
- the downpipe can be flushed once, after the rinse, rather than twice.
In its November 2025 guide, Which? Trusted Traders gives a typical UK range of £75 to £350 ex VAT for emptying every gutter on a house, and a conservatory gutter is one small part of that.
Look also along the line where the glazing butts against the house wall. A lead or flexible flashing that has lifted at that line lets water behind the frame, and cleaning cannot cure it. Our guide to moss blocking gutters explains what the overflow looks like from the ground.
Questions for whoever does the work
A conservatory roof clean is a small job, but it is worth getting the access and the method agreed before the day. These questions get a useful answer from any roofer or cleaner:
- How will you reach the roof without standing on the glazing?
- What cleaner will you use, and is it suitable for polycarbonate as well as glass?
- Will the gutters and downpipes be cleared and flushed on the same visit?
- If you find a split seal or a cracked pane, will you tell me before carrying on?
The answer to the last question matters most. A cleaner who finds a hairline crack and keeps washing may turn a repair into a replacement. If a crack or a failed seal turns up, the sensible order is to stop, photograph it and decide on a repair before the roof is wetted further.
For wider cleaning jobs, see our page on how a roof is reached for cleaning, or go back to roof cleaning and moss removal for the main service.
