Conservatory Roof Cleaning Explained

Your conservatory was meant to be the bright, sunny room of the house. Instead you look up through green streaks, black spots and a film of grime that dulls every bit of light coming in.

It creeps up slowly, so you might not notice how bad it has got until a sunny day shows it off. The good news is that a conservatory roof cleans up beautifully when it is done the right way. Here is how it works and what you should expect.

The quick answer: A conservatory roof needs gentle, low-pressure soft washing, not a high-pressure blast. The glass or polycarbonate, the seals, the aluminium bars and the gutters all get cleaned by hand and with the right products, so grime lifts off without damage and the room fills with light again.

1. Why conservatory roofs get so grubby

A conservatory roof sits at a low angle, and it usually tucks up against the main house wall. That combination traps dirt, leaves and rain runoff exactly where they can settle. Add our damp South East climate and you have perfect conditions for algae.

The green and black streaks you see are living growth, not just dust. They feed on the film of grime that builds on the surface, and they spread fastest on the shaded side that never dries out fully. Polycarbonate roofs are especially good at holding this in their ridges and channels.

Left alone, it only thickens. What starts as a faint tint turns into heavy staining that blocks daylight and makes the whole room feel cold and dim.

2. Soft washing is the method that suits it

Conservatory roofs are delicate. Glass panels, plastic sheets, rubber seals and slim aluminium glazing bars all sit together, and a high-pressure jet can force water past seals, mark the surface or crack older polycarbonate. That is the last thing you want above a room full of furniture.

Soft washing solves this. It uses low pressure and a biocide that kills the algae and mould at the root, so growth lifts away instead of being blasted off. The surface gets cleaned gently, the seals stay intact, and the room underneath stays dry.

Because the treatment works at the root, the finish lasts. You are not just wiping the surface for a week or two, you are clearing the growth properly.

3. It is not just the panels

A proper conservatory clean covers more than the glass. The glazing bars that hold everything together collect grime along their length, and they look grubby even when the panels are clear. They get cleaned too.

The ridge along the top, the flashing where the roof meets the house wall, and the finials or trims all gather dirt and algae. Cleaning these makes the difference between a roof that looks freshly done and one that only looks half sorted.

Frames and any external sills get attention as well, so the whole structure lifts together rather than leaving clean glass framed by dirty bars.

4. Conservatory gutters block up quietly

Most conservatories have their own small gutters, and they are easy to forget because you rarely see them. They are also narrow, which means they clog fast with leaves, moss washed down from the main roof, and general debris.

A blocked conservatory gutter overflows against the wall and the frame, and that is where damp problems start. Water sitting where it should not be works away at seals and brickwork over time.

Clearing these gutters is part of doing the job properly. It keeps water moving off the roof and away from the structure, which is exactly what they were built to do.

• Glass and polycarbonate panels: the main surface, cleaned gently so light floods back into the room.
• Glazing bars and ridge: the aluminium frame and top capping that look grubby even when the panels are clear.
• Flashing at the wall: where the conservatory meets the house, a favourite spot for algae and trapped grime.
• Conservatory gutters: the narrow channels that block quietly and overflow against the frame.
• Finials and trims: the small finishing pieces that pull the whole clean together.

5. What the day itself looks like

Most conservatory roofs are reached and cleaned from the outside using the right access, working panel by panel. It is careful work rather than a quick blast, so the pace suits the delicate surfaces.

You will usually notice the difference straight away, because dirt on glass shows up the moment it is gone. The room feels brighter, sunlight comes through properly, and the streaks that used to catch your eye have lifted.

Where soft washing has treated algae at the root, the surface keeps looking cleaner for longer, since the growth was killed rather than smeared around.

6. Keeping it clear afterwards

A clean conservatory roof does not need constant fuss, but a few habits help. Keeping overhanging branches trimmed cuts down the leaves and sap that land on the glass, and it lets the surface dry out faster after rain.

Clearing the conservatory gutters now and then stops that quiet blockage from building back up. It is a small job that saves a bigger one later.

Beyond that, a periodic soft wash keeps the algae from taking hold again. How often depends on how shaded and sheltered your conservatory is, which is easy to judge once you have seen how quickly yours discolours.

Frequently Asked Questions

Can you pressure wash a conservatory roof?
You really should not. High pressure can force water past the seals, mark the surface and crack older polycarbonate. Soft washing at low pressure is the safe way to clean it.

Will cleaning get rid of the green streaks for good?
Soft washing kills the algae at the root, so it lifts away properly and stays gone far longer than a quick surface wipe. Growth can return over time, which is why a periodic clean helps.

Do you clean polycarbonate as well as glass?
Yes. Both are cleaned with the same gentle, low-pressure approach. Polycarbonate tends to trap more grime in its ridges, so it often looks the most improved.

Does the inside of the roof get cleaned too?
The service covers the outside of the roof, where the algae, grime and weather damage build up. That is what blocks the light and causes the staining you see from below.

How often should a conservatory roof be cleaned?
It depends on shade and shelter. A conservatory under trees on a north-facing wall discolours faster than one in an open, sunny spot, so the right interval is the one that suits your setup.

Ready to get the light back in your conservatory?
Ben's Roof Cleaning cleans conservatory roofs, gutters and more across London and the South East, with over 15 years of experience. Get in touch or call 01342 778892 for a free, no-obligation quote.

A clean conservatory roof turns a dim room bright again

Your conservatory is only as good as the light it lets in, and a grubby roof steals most of that. Gentle soft washing clears the panels, bars, flashing and gutters without risking the seals, and it keeps the algae from bouncing straight back. Get it done right and you get the sunny room you paid for.