New polycarbonate or insulated roof panels?

When a polycarbonate roof starts to leak, discolour or crack, the cheapest two fixes both keep your existing roof frame. You can re-sheet it with new polycarbonate, or you can fill the same bars with insulated panels. They cost about the same, and they are fitted in a similar time, but they give you very different rooms.

New polycarbonate gives you back the conservatory you had when it was new: bright, hot in summer, cold in winter and loud in the rain. Insulated panels give you a darker but far more comfortable room, with one extra question to settle first: building regulations.

New polycarbonate vs insulated panels at a glance

	New polycarbonate roof	Insulated roof panels
Price, medium conservatory (about 4m x 3.5m), fitted	£2,700 to £5,200 (typically about £3,900)	£1,800 to £4,600 (typically about £3,100)
Heat lost (U-value, W/m²K)	1.3 to 1.7 for 25mm to 35mm sheet (up to about 2.4 for 16mm)	0.29 to 0.5 (0.29 is the makers’ centre-of-panel figure; the old bars add to it)
Sun’s heat let in through the roof	8% to 63%, from Solarguard tint to clear	None
Time on site	1 to 2 days	1 to 3 days
Building regulations	Exempt when like for like	Depends on the system; LABC’s view is that approval is likely needed
Lifespan	10 to 20 years	15 to 25 years
Daylight through the roof	Good when new, falling as sheets discolour	None: the roof becomes opaque
Rain noise	Loudest of any roof	Much quieter

Prices are our site-wide ranges for a medium conservatory (about 4m x 3.5m) across lean-to, Edwardian, Victorian and gable shapes, fitted; installers usually quote including VAT, but check. Polycarbonate figures are from Ultraframe’s published data for its 25mm and 35mm sheet; panel figures are makers’ claims from Thermotec and Superior Conservatory Panels.

Which is warmer in winter?

Panels, clearly. Ultraframe rates its 25mm polycarbonate at 1.7 W/m²K and its 35mm sheet at 1.3. Thinner sheets are worse: one panel maker quotes 2.4 for 16mm. Panel makers quote 0.29 for a 75mm insulated panel, so the panels themselves lose around a fifth of the heat of good polycarbonate or less.

The limit is the old roof frame. A panel conversion keeps the existing glazing bars, ridge and eaves, and a solid roof installer argues that heat is still “lost at the same rate through the bars and ridge of the existing roof”. That applies equally to new polycarbonate, so it does not change which option is warmer, but it does mean a panel roof will not perform like a purpose-built insulated roof at 0.15. Condensation is the other winter issue. Retail guidance says condensation under polycarbonate is common, and the same critic warns that panels without thermal breaks in their aluminium skins can create cold spots of their own. See our page on conservatory condensation.

Which stays cooler in summer?

Panels, because they let no sun through the roof. Clear 25mm polycarbonate lets through 63% of the sun’s heat on Ultraframe’s figures, opal 37%, bronze 26% and its Solarguard tint 8%. The darker tints help, but they darken the room too. Temperature control is the single biggest complaint about conservatories: 24% of Which? members surveyed in April 2026 said the temperature is difficult to regulate, and Which? says polycarbonate can be “a false economy” for that reason.

How much light will you lose with panels?

All of the light that comes through the roof. Clear polycarbonate lets through about 68% of visible light when new, so switching to panels makes a real difference, especially if a room behind the conservatory borrows its light. The side windows and doors still let daylight in. If you want to keep a see-through roof but lose the noise and some of the heat, look at glass instead: see glass vs polycarbonate.

Which is quieter in the rain?

Panels. Which? says polycarbonate can be noisier, particularly in rain, and ExpertSure calls rain noise the most-cited complaint about it. No independent decibel tests were found, but one panel maker quotes customers who “no longer need ear defenders when it rains”. New polycarbonate will be as loud as the old sheets, whatever the thickness. Our page on a noisy conservatory roof has other options.

Cost and value for money

The price ranges overlap: our typical figures are about £3,900 for new polycarbonate and £3,100 for panels on a medium conservatory, so panels are often slightly cheaper. Full external insulated panel roof systems are a different, dearer product, at around £6,000 to £12,000 on Warmer Roof’s figures. Both jobs reuse the existing bars. On a re-sheet, the glazing bar caps and their clips often break when prised off and need replacing, and one supplier replaced the bars themselves on a roof at least 10 years old as a precaution. Ask whether bar repairs are in the price for either option. See polycarbonate roof costs and insulated panel costs.

Guarantees are similar on paper. Ultraframe and Exolon offer 10 years on their polycarbonate sheet, and Thermotec’s panels carry a 10-year guarantee according to a review. A critic of panel systems says the guarantee often covers “only the panels themselves”, so check whether leaks at the bars and ridge are included.

Bills are unlikely to fall much either way. MoneySavingExpert users who fitted panels reported a more usable room but negligible energy savings. One polycarbonate installer claims high-insulation sheet cuts winter heat loss by up to 80%, without saying against what, so treat that with care.

Building regulations and paperwork

New polycarbonate replacing polycarbonate is generally exempt, provided the conservatory still meets the exemption afterwards: ground level, no more than 30m², separated from the house by external doors or windows, and not heated by the house’s central heating.

Panels are different. Some panel sellers say no building regulations are needed; a review of Thermotec repeats that claim. LABC’s guidance says that work which “significantly reduces the proportion of glazing, or level of translucence to the roof” means the conservatory “can no longer be considered exempt”, and it specifically mentions products that underdraw or overclad existing polycarbonate roofs. There is no published ruling on panels as such, so ask your council’s building control before you sign. Treat a flat “you don’t need building regs” as a red flag, and get the installer’s position in writing.

Weight is part of the same conversation. Polycarbonate weighs only a few kilos per square metre, and LABC says frames under a polycarbonate roof “may only have sufficient reinforcement to carry that particular load”. The panel makers in our research do not publish weights, so ask for the figure and how your frames were checked.

Looks and resale

New polycarbonate looks bright and clean when fitted, but it discolours again with age, and buyers tend to see it as the sign of an old conservatory. Panels keep the conservatory’s outline and bars but read as a solid roof from outside. No independent figures show what either adds to a sale price.

Paperwork and energy ratings are where panels need more care. Since 6 August 2026, a conservatory whose replaced roof is less than 75% glazed is recorded as an extension on an energy assessment, and a pitched roof with no evidence of insulation is entered as uninsulated. Keep the panel specification and any building control certificate with your house papers.

New polycarbonate or insulated panels: which should you choose?

• You mostly use the room in spring and autumn and love the light: new polycarbonate in 25mm or 35mm, or glass if you can stretch the budget.
• It is too hot in summer, too cold in winter and too loud when it rains: insulated panels.
• You are selling soon and want no paperwork questions: new polycarbonate.
• The bars, ridge or gutters leak or sag: fix or replace those first; neither option cures a failing frame. A full tiled roof replaces the lot.
• A kitchen or lounge behind the conservatory borrows its light: polycarbonate or glass, not panels.

When you get quotes for panels, ask for the whole-roof U-value rather than the panel figure, what the guarantee covers, the panel weight, and who will handle building control.