Conservatory roof cleaning guide

A dirty conservatory roof does more than look bad — it blocks the light the room was built for. But conservatories are also among the easiest roofs to damage with the wrong approach. The panels, seals and frames all need a lighter touch than a tiled roof. Here is how to get it right.

Why do conservatory roofs get dirty so fast?

It is mostly geometry. Conservatory roofs are low-pitched, so rain does not wash them the way it washes a steep tiled roof — water sits, and algae loves standing water. They are often shaded by the house wall on one side, keeping them damp. Add overhanging trees dropping leaves, sap and bird droppings, and you have ideal growing conditions a few metres above your patio.

The result is the familiar green film, usually worst on the shaded side and along the panel bars where water collects. It builds gradually, then seemingly all at once — which is why regular light cleans beat occasional heroic ones.

Glass vs polycarbonate: does it matter?

Yes, and it is worth knowing which you have. Glass panels are tougher: they resist scratching and handle cleaning products well. Polycarbonate — the lightweight, slightly flexible plastic used in many conservatories — scratches easily and can be dulled by abrasive pads, harsh chemicals and even some solvents. If you are unsure, treat it as polycarbonate and be gentle.

Either way, the seals between panels and the frame gaskets are the vulnerable part. They keep weather out, and aggressive cleaning — pressure washers especially — is what destroys them. Gentle methods protect the seals; forceful ones do not.

The safe method, step by step

Start by clearing leaves and loose debris with a soft brush — dry, before any water. Then wash with a soft brush or water-fed pole using pure or soft water and a mild, non-abrasive conservatory cleaner. Work in sections across the panels, not forgetting the frame bars and the gutters and box gutters at the edges, which clog just like house gutters.

Rinse thoroughly with clean water and let the roof air dry — this is what gives a streak-free finish, especially with pure water, which dries without leaving mineral spots. Avoid squeegeeing polycarbonate dry, as grit trapped under the blade can scratch. Work from a stable ladder or from the ground with a pole; never climb onto the roof.

What should you never do?

Never pressure wash a conservatory roof. The jet can crack panels, blast seals out of the glazing bars and drive water into the frame, where it shows up as leaks inside. Never use abrasive pads, wire wool or harsh chemicals on polycarbonate — they scratch and cloud it permanently. Never lean ladders directly against gutters or unsupported panels. And never walk on the roof: conservatory structures are not built to carry a person's weight.

When should you call a professional?

If you cannot safely reach the whole roof from a ladder, if the algae is thick and established, or if the seals and frames need attention too, a professional clean is the sensible option. A professional will use a water-fed pole system from the ground — pure water, no pressure, no ladder acrobatics — and will clean the frames, seals and gutters as part of the job. It is also worth having the seals checked periodically: perished seals cause most conservatory leaks, and a cleaner working up close is well placed to spot them.