How do you clean a conservatory roof safely?

Most of a house roof is made to be walked on, carefully, by someone who knows where to put their feet. A conservatory roof is not. Glass cracks under a boot. Polycarbonate flexes, and sheets that look sturdy from below can give way where they span between bars. A tiled or solid conservatory roof is sturdier, but the frame beneath was often built for a lighter load than the tiles now laid on it.

So the first rule of cleaning is the simplest: nobody stands on the glazing, and nobody leans a ladder against it. Work is done from the ground on a pole, from a tower beside the structure, or across a purpose-made spreader that shares weight over the frame. If access is awkward, perhaps because the conservatory sits between the main house and a boundary fence, you need a plan before anyone lifts a brush. Our page on roof cleaning access sets out how that is solved.

Glass roofs are the easiest to clean. A soft brush or sponge on a pole, warm water and a small amount of non-abrasive cleaner lift algae and dirt without leaving marks. Rinse with a hose rather than a jet. Hard brushes can scratch self-cleaning coatings on the outer face, which is the very surface that makes the glass easier to maintain.

Polycarbonate is less forgiving. The sheets scratch easily, and the flutes inside can fill with water or dust if a jet forces moisture through damaged end seals. Use a soft cloth or brush, cool water and a gentle cleaner, and skip anything with solvents.

A tiled or solid conservatory roof is cleaned in the way you would clean any pitched roof of the same covering, with hand removal of moss and a low-pressure biocide. The difference is the smaller area, which tempts people into using stronger tools. Don't. A gentle wash on the same principles as in our page on black streaks on a roof works well here too.

The usual mistakes are easy to list. A pressure washer on a conservatory roof forces water through the rubber glazing gaskets and into the room. Strong bleach damages the seals and the frame finish, and runs down the glass onto planting below. A ladder rested on the glazing chips or cracks it.

Then there is the roof itself. Over years, conservatory seals shrink and harden, and the aluminium glazing bars may no longer be fully watertight. A clean can expose that, simply because the roof now looks bright enough to see a stain at the joint. That is useful information, but it can be mistaken for something the cleaner has caused.

If you do clean from inside, reach only what you can with a long-handled sponge, and never lean on the frame. For most households the combination of a safe outside wash and a good look at the seals is better done by someone with the right access gear.

HomeBuilding and The Eco Experts both put the working life of polycarbonate at roughly 10 to 15 years, while a tiled conservatory roof can run past 50 years. A polycarbonate roof that has yellowed, clouded or turned brittle will not come clean however well it is washed. At that point a clean only buys a little time.

Thinking of a new roof instead? Swapping the glazing for a solid roof is classed as material alteration work under the Building Regulations, so Homebuilding and Renovating says you must submit a building control application. Heavier materials put more weight on the old frame. MyBuilder's conservatory roof guide, updated on 21 August 2026, gives a typical UK range of £2,000 to £10,000 or more for replacement, with a polycarbonate roof at £2,000 to £5,000. That is a very different decision from cleaning, and we cover it only when a survey shows the roof has reached the end.

Good conservatory cleaning includes a look at the roof edges and the join with the house wall. That is where lead or sealant flashing meets the brickwork, and where leaks nearly always begin. We look at the ridge cap, the gutter fall and the eaves seals, and tell you what we find with photographs.

Moss and algae in this setting can also be a sign of poor drainage. A sagging gutter or a choked downpipe floods the lowest panels and keeps them wet. Sorting the gutter often does more for the roof than the wash itself.

Many owners ask whether a cleaner will promise to keep the roof clear for good. Our page on moss-free guarantees explains what such promises mean in practice.

A conservatory attached to a listed building, or one standing in a conservation area, may be under extra controls, especially if the glazing or the frame is old. Cleaning is normally maintenance, but replacing materials is another matter. Our page on cleaning listed roofs covers the permissions to ask about, and it is sensible to check with Swindon Borough Council's planning team if you are unsure.

To have a conservatory roof surveyed, ring 01793 626096 or use the form on this site, and see the wider roof cleaning and moss removal service for what else we can look at on the same visit.