Polycarbonate was what most British conservatories were roofed with, and most of those roofs are now at or past the end of their useful life. The sheets discolour, the seals at the glazing bars perish, the multiwall flutes fill with algae and condensation, and the noise in heavy rain was never popular. The question is what to put back.
Why it fails, and how to tell it has
Polycarbonate is a plastic exposed to ultraviolet light on a roof, and over years it yellows and becomes brittle. The dark or green streaks visible inside the flutes are algae and dirt drawn in through the open cell ends where the sealing tape has failed. Leaks appear at the glazing bar gaskets and at the top abutment rather than through the sheet itself. A roof that drips at a bar in heavy rain and has streaked flutes is telling you its seals have gone.
Re-sheeting: the cheap option that is sometimes right
Replacing the polycarbonate sheets within the existing frame, with new gaskets and properly taped and vented cell ends, is much the cheapest of the options and restores what the roof originally did. It makes sense where the frame is sound and the budget is the constraint, and it is honest to say that it puts back a roof with the same thermal and acoustic limits as before. Thicker multiwall sheets perform better than the thin ones many conservatories were built with.
Upgrading to glass or to a solid roof
Glass with modern coatings keeps the daylight and transforms the comfort, and is heavier than polycarbonate so the frame is checked. A solid insulated roof makes the room usable year round and quiet in rain, is heavier again, and normally brings the work under the building regulations. The honest ranking on comfort per pound is usually solid, then glass, then new polycarbonate; on daylight it is the reverse of the first two.
What a conservatory polycarbonate roof replacement cost should separate
Whether the existing frame is being reused or replaced, what the sheet or panel specification is, whether the glazing bar gaskets and the top abutment flashing are being renewed, how the roof is being ventilated at the eaves and the ridge, and who certifies the work if it is notifiable. The abutment where the roof meets the house is worth naming specifically, because if that was the leak, new sheets will not cure it.
Questions people ask about polycarbonate conservatory roof replacement
How long does a polycarbonate conservatory roof last?
The sheets have a finite ultraviolet life and most British conservatory roofs of this type are now well into it. Seals and tapes usually fail before the sheet becomes structurally unsound.
Can I replace polycarbonate conservatory roof sheets only?
Yes, where the frame is sound, and it is much the cheapest option. It restores the original performance rather than improving on it.
Why is my polycarbonate roof leaking at the bars?
The glazing bar gaskets perish with age and ultraviolet exposure. That is a repair in its own right and it is often mistaken for a failure of the sheets.
Is polycarbonate noisy in rain?
Noticeably, and it is one of the main reasons people upgrade. A solid insulated roof is the quietest option and glass sits between the two.