How to stop your conservatory roof going green

A conservatory roof goes green because of algae and moss, which thrive in the damp, shaded, still conditions on top of a conservatory. The only reliable fix is regular cleaning with a soft brush and a suitable conservatory or algae cleaner, followed by a thorough rinse. No treatment stops algae coming back permanently, but cleaning before it takes hold, and keeping gutters and nearby trees in check, keeps the roof clear for much longer.

Why conservatory roofs turn green

Algae is an airborne organism that settles anywhere damp and undisturbed. Conservatory roofs are a perfect home: they stay wet after rain, often sit in partial shade, and rarely get touched. North-facing roofs and those under trees go green fastest. Once a film of algae forms, it holds more moisture, which encourages moss to follow, especially in the joints and along the bottom edge.

How to clean a green conservatory roof safely

Safety comes first: conservatory roofs are not designed to take your weight, so never climb or kneel on the panels.

• Use a soft-bristled brush on an extendable pole to work from the ground or a stable platform.
• Apply a cleaner made for conservatory roofs or a general algae and mould remover.
• Work from the top down, loosening the green film gently rather than scrubbing hard.
• Rinse thoroughly so no residue is left to streak the panels.

Our step-by-step guide to cleaning a conservatory roof goes into more detail on tools and technique.

What not to do

Avoid pressure washers on polycarbonate or glass roof panels, the force can crack seals and force water inside. Skip abrasive pads and harsh solvents that scratch or cloud the panels. And do not ignore a green roof for years; the longer algae and moss sit there, the harder they are to remove and the more they can damage seals and trims.

How to slow the green coming back

• Clean before it takes hold: a light clean once or twice a year is far easier than tackling thick algae.
• Keep gutters clear: blocked conservatory gutters keep the roof wetter for longer. See how often gutters should be cleaned.
• Cut back overhanging branches: more light and air movement means less algae.
• Treat after cleaning: some algae inhibitors slow regrowth, though none are permanent.

When to get it done professionally

Cleaning a conservatory roof safely from the ground is possible for a small, accessible roof, but larger or higher roofs, and stubborn moss in the joints, are best left to a professional. Our conservatory cleaning service covers the roof, glass, frames and gutters in one visit using the right equipment, so the room is bright again without any risk to you or the panels. A clean before summer makes the biggest difference, as covered in our guide to cleaning a conservatory before summer.