Roof Types
Glass and polycarbonate are the two traditional conservatory roof materials, and both perform far worse thermally than a warm roof — but the difference between the two matters if you are not ready to specify a full warm roof.
A glass roof uses sealed double-glazed units in an aluminium grid, while a polycarbonate roof uses lightweight multi-wall plastic sheets, and glass outperforms polycarbonate on thermal comfort, noise and appearance.
Polycarbonate was the standard specification through the 1990s and 2000s because it was cheap and light. Glass roofs became more common as double and triple-glazed roof units became affordable.
Polycarbonate is significantly noisier in heavy rain than glass, because the thin multi-wall sheets resonate under impact.
This is one of the most common complaints about older Glasgow conservatories and, on its own, is often the reason homeowners look at a roof replacement.
A glass roof costs more than polycarbonate to install new, typically by £1,500 to £3,000 depending on roof size, but neither comes close to matching a warm roof's thermal performance.
| Roof type | Approx. U-value | Relative cost | Noise in rain |
|---|---|---|---|
| Polycarbonate | 2.6 W/m²K | Lowest | Loud |
| Standard glass units | 1.6 W/m²K | Mid | Quiet |
| Low-e argon glass | 1.0 W/m²K | Mid-high | Quiet |
| Full warm roof | 0.15 W/m²K | Highest | Silent |
For a new conservatory we recommend skipping both and specifying a warm roof or a hybrid roof with glazed panels, because the cost difference against glass is smaller than most homeowners expect.
See our warm roof page for the full cost comparison — the gap between a glass roof and a warm roof is often only £3,000 to £6,000 on a like-for-like build.
Yes, on most existing frames, but a warm roof replacement is usually a better use of the same budget because it solves the noise, heat loss and glare problems in one job rather than just one of them.
