How long does a polycarbonate roof last?

Two national sources give a number worth working from. HomeBuilding and Renovating, in an April 2024 piece on conservatory roof replacement, quotes a typical lifespan of 10 years for polycarbonate. The Eco Experts, updated in April 2024, says about 10 to 15 years for a glass or polycarbonate conservatory roof, although another passage on the same page suggests polycarbonate can last 15 or 20 years. The two pages do not agree, so we work from the middle ground of around 10 to 15 years.

That band is a typical range. A roof with good multiwall sheet, sealed ends and a sheltered aspect can sit comfortably at the top of it, and a thin sheet under a tree can fall below it. A solid or tiled conservatory roof is a different proposition: The Eco Experts quotes around 50 years for that type, which is one reason owners at the end of a polycarbonate roof's life often look at the alternatives in our guide to glass, polycarbonate and tiled conservatory roofs.

Polycarbonate is a plastic, and sunlight is hard on plastic. Over the years the outer face can cloud, yellow or craze, and the sheet can become more brittle than it was on the day it was fitted. Better sheets carry a protective layer on the sunward face to slow this down. Cheaper ones do not, so a pair of roofs fitted in the same year can look quite different by now. A roof that faces south with no shade from trees takes the hardest daily dose of sun, and it is usually the first to show its age.

The edges and the fixings

Multiwall sheet is made of hollow channels, and those channels must be closed at the top with a sealing tape and at the bottom with a vented one. When tape peels, water and dust get in, and green algae starts to grow inside the sheet where no brush can reach. Glazing bars and their rubber gaskets perish as well, so the weak point is often the joint rather than the sheet.

Movement

A plastic sheet expands and contracts with the temperature. Over time that movement works at the fixings and opens small gaps along the bars. When we inspect one, the bars and the ridge get our attention before the sheets, since leaks tend to begin there. Look along each bar from inside on a bright day and you can often see where daylight or a thin line of damp has found its way in.

None of these means the roof must be replaced tomorrow, but several together point one way.

• Yellowing or a milky look that does not wipe off, and light that looks dimmer than it used to.
• Green or brown staining inside the channels, which suggests the end seals have failed.
• Cracks, especially at the fixings, or sheets that rattle in wind.
• Drips at the glazing bars in heavy rain, or damp marks on the frame below.
• Rubber gaskets that have shrunk, hardened or pulled away from the sheet.
• A roof that is much hotter in summer and colder in winter than it used to be, as the sheet clouds and the sealing fails.

A single cracked sheet is a repair question, and our answer on replacing one polycarbonate sheet covers when that is sensible. A roof that shows several of the signs above across most of its sheets is usually past patching.

MyBuilder's 2026 conservatory roof replacement guide gives a typical range of £2,000 to £5,000 for polycarbonate, against £3,000 to £8,000 for glass and £5,000 to £10,000 for a solid roof. The same guide adds £500 to £2,000 where the frame needs reinforcement. Those are national typical figures from a cost guide rather than anyone's price for your roof. The quote for yours comes after we have measured it, and it covers the whole job.

The frame matters more than people expect. Homebuilding cautions that the frame under an old polycarbonate roof may now have to bear a heavier covering, and polycarbonate weighs very little beside glass or a solid roof, so what carried it happily can struggle with its successor. We check the frame, the base rail and the ring beam of the conservatory before recommending a heavier covering. If you are weighing up a solid roof, our answer on planning for a solid conservatory roof explains what to ask the council.

Cleaning helps, and so does doing it gently. Warm water, a squirt of washing-up liquid and a sponge on a long handle will do, followed by a good rinse. Avoid pressure washers, abrasive pads and strong solvents, which can scratch the face of the sheet and let in the cloudiness you are trying to avoid. Clear leaves and moss from the gutters and the valley between a conservatory and the house roof, because standing water and debris age a seal quickly.

Once a year, look at the end tapes, the gaskets and the cappings. A small bead of the right sealant on a failing joint costs little and buys a season or two. Beyond that, ageing sheets are not worth chasing with repairs, and our answer on how long a replacement takes sets out what the work involves. Our conservatory roof replacement page sets out how we survey, and the finished work is covered by a written 10-year workmanship guarantee.