How to keep a conservatory roof clean, and how often

Most conservatory roofs need a proper clean twice a year, in spring and autumn, and more often if trees hang over them or they face north. Clean from the ground with a soft brush and mild soapy water or pure water, and never stand on the roof or blast it with a pressure washer.

That's the short answer. Below is how to do it safely, what to avoid, and when it makes sense to hand the job over.

How often should a conservatory roof be cleaned?

Twice a year suits most homes. Homebuilding & Renovating's conservatory roof guide recommends a clean in spring and another in autumn, so you clear the winter grime and then the leaves before the wet months. Some roofs need more attention:

• Under or near trees. Falling leaves settle in the roof joints and block the gutter outlets. The same guide notes that conservatories surrounded by trees need regular checks to stop water backing up.
• North-facing. Less sun means the roof stays damp for longer, and the guide flags a higher risk of mildew on north-facing conservatories.
• Busy roads or open fields. If you can see a film building up on the panels from inside, that's your cue, whatever the calendar says.

Whether you're in Sileby, Syston or Loughborough, the simplest test is to stand inside on a bright day and look up. If the light looks dull or green, it's time.

Why a dirty roof is more than a looks problem

A green conservatory roof is the most obvious sign, but the real issues are underneath it:

• Moss, algae and leaf mulch hold moisture against the seals and glazing bars.
• Debris washes down into the gutter, which can block and overflow onto the frame and walls.
• A dirty roof lets in noticeably less light, which is the reason most people built the conservatory in the first place.

A regular, gentle clean also gives you a chance to spot cracked panels, slipped seals or tired paintwork early. It's much cheaper to deal with those then than after a winter of leaks.

How to clean a conservatory roof safely

The safest roof clean is one done entirely from the ground or a properly footed ladder at the side, never from on top. Homebuilding & Renovating's step-by-step method is a good starting point:

• Clear loose debris first. Use a soft-bristled brush on a telescopic pole to lift off leaves and moss before adding water, paying attention to the joints and the gutter.
• Wash with a gentle solution. Warm water with a mild detergent, or a cleaner made for your roof type (glass or polycarbonate).
• Work top to bottom in sections, using light pressure with a sponge or soft brush head.
• Rinse thoroughly with a hose.
• Clean the frame and fixings, and check the seals and paintwork while you're there.
• Dry glass roofs with a microfibre cloth or squeegee for a streak-free finish. Polycarbonate doesn't always need drying, and some manufacturers say not to use a squeegee on it (see below).

Professional window cleaners often use water-fed poles with purified water instead. At Pure Flex we use pure-water poles that reach up to about 20 m, so we can clean a conservatory roof and its frames without anyone climbing onto it.

What to avoid

• Standing or kneeling on the roof. The Health and Safety Executive's guidance on roof work says all roofs should be treated as fragile until a competent person confirms otherwise, and warns not to trust any sheeted roof, whatever the material. A conservatory roof is not built to take your weight.
• Pressure washers. In the Homebuilding & Renovating guide, the managing director of Hampton Conservatories warns they can damage seals and coatings and force water into the structure, even on low settings.
• Bleach and harsh cleaners. These can harm protective coatings and seals.
• Abrasive pads and sharp tools. Palram, a major polycarbonate manufacturer, says in its polycarbonate care and maintenance sheet never to use abrasive or high-alkaline cleaners, sharp objects, razors or squeegees on its sheets.
• Cleaning in strong sun. Palram also advises against applying cleaners in direct sunlight.

Glass or polycarbonate: does it change anything?

Yes, a little. Glass is the more forgiving surface: a gentle wash, a rinse and a dry with a microfibre cloth will bring it up well.

Polycarbonate scratches more easily. Palram's advice is a soft cotton cloth or sponge, lukewarm water and a mild washing-up liquid, then a cold-water rinse and a dry with a soft cotton cloth. Don't dry-brush dusty polycarbonate either, because the grit can scratch the surface. Some polycarbonate sheets also have an anti-condensation coating on the inside that the manufacturer says shouldn't be cleaned, so check what your roof is made of before you start inside.

If you're not sure what your roof is, a professional cleaner will be able to tell you on the first visit.

When to call in a professional

Do it yourself if your conservatory is low, easy to reach and you can work safely from the ground. For a high roof, a lean-to against a two-storey wall, or a roof that's already heavily green, a specialist is the safer choice. The Homebuilding guide makes the same point, adding that a professional can spot problems that need repair.

Pure Flex cleans conservatory roofs and frames across Leicestershire as part of our home exterior cleaning service, either as a one-off or added to your regular window round. Our team is DBS checked and fully insured. Pair it with a gutter clear, since the two are linked: see our guide on when to clean your gutters. When you're ready, you can book online or ask for a free quote.