Conservatory Roof Cleaning: Polycarbonate, Glass and the Frames

Polycarbonate versus glass

Polycarbonate is the multi-wall plastic sheeting used on most older conservatories. It scratches easily, it discolours with UV over time, and its internal flutes can grow algae that no external cleaning will reach. Externally it cleans well with a soft brush and detergent at low pressure; internal flute growth means the sheet is at the end of its useful life.

Glass is far easier. Modern self-cleaning coated glass needs little more than a rinse and gentle wash — and importantly, it must not be cleaned with abrasive pads or harsh chemicals, which destroy the coating. Standard glass can be washed like any window with a soft brush and pure water.

Never walk on it

Conservatory roofs are not load-bearing. Polycarbonate will not support an adult and glass panels are not designed for point loads either. Falls through conservatory roofs are a well-documented cause of serious injury.

The correct method is a water-fed pole system from the ground, which allows the whole roof, frames and gutters to be cleaned safely with purified water and a soft brush head, or a suitably positioned tower where the layout demands it. If a contractor suggests climbing onto the roof, decline.

• Water-fed pole with soft brush from ground level
• Purified water so no drying spots are left
• Low pressure only — never a pressure washer on polycarbonate
• No abrasive pads or solvent cleaners on coated glass

The box gutter matters most

Where the conservatory meets the house there is usually a box gutter or a lead-lined channel taking the run-off from the main roof. It is out of sight, it is where all the roof debris ends up, and when it blocks the water goes into the wall junction and then inside.

This is the part of conservatory maintenance that actually protects the building, and it is routinely ignored because nobody can see it. It should be cleared and flushed at least annually, more often if the main roof carries moss.

Frames, seals and finishing

uPVC frames and glazing bars go green and grey and respond well to a soft wash with an appropriate cleaner. Heavily oxidised white uPVC that has gone chalky will improve but not return to new — a uPVC restorer can help where the plastic is otherwise sound.

While cleaning, it is worth checking the seals and the capping. Perished rubber gaskets, lifted capping strips and failed sealant at the wall junction are common causes of conservatory leaks and are much cheaper to address than the interior damage they cause.

Cost and frequency

A typical conservatory roof clean including frames and gutter clearance generally costs £80 to £200 depending on size and access. Larger orangery-style structures and those with difficult access sit above that. It is often bundled cost-effectively with a gutter clean or roof clean on the main house.

Annually is a sensible frequency, ideally in spring so you get the benefit of the light through summer. Where the conservatory sits under trees or beneath a mossy main roof, twice yearly clearance of the box gutter is prudent even if the glazing itself can wait.

The bottom line

Two things matter more than the glazing itself. The first is safety: never climb onto a conservatory roof, and be wary of anyone who offers to. The second is the box gutter behind it, which is invisible from the ground, collects everything shed by the main roof, and causes the leaks that get blamed on the conservatory structure.

Get both right and the rest is straightforward. An annual clean of the panels and frames from a water-fed pole, plus a clearance and flush of the box gutter, keeps a conservatory bright and dry for a fraction of what a leak repair costs. It is one of the easier maintenance wins on a house, and one of the most consistently neglected.

Frequently asked questions