Will a solid roof cut my heating bills?

Glass and polycarbonate let heat out quickly. A solid roof has timber rafters, insulation, a waterproof layer and a tile or slate-effect covering, and the insulation does the work of slowing the loss. The legal benchmark is Part L 2021 Table 4.2, which sets a U-value of 0.15 for new or replacement roofs on an existing home. A lower number means less heat passes through.

The Eco Experts (updated 2024) put a solid or tiled conservatory roof at around 50 years, against about 10 to 15 for glass or polycarbonate. That figure describes the typical case rather than any assurance, but it explains why owners treat the cost as long term. Our guide to insulating a conservatory roof compares the options.

The change owners notice first is comfort. A room too cold to sit in on winter evenings, or too bright and hot in summer, becomes usable for more of the year. That is not the same as a lower bill. Some owners use the extra comfort to heat the room more often, so spending stays level while the room earns its keep.

Savings differ from house to house, so a single percentage would mislead. The result depends on the orientation, the size of the roof compared with the walls, the quality of the doors and windows, and whether the room is open to the house. A conservatory closed off by a door will behave differently from one opened up as part of the living space.

One test is to look at last winter. If the room sat unused from November to March, a warmer roof may bring it into service rather than save money, and the heating cost then rises a little while the usable space grows. If you already heated it daily, the effect is more likely to appear as lower use of the radiators or heater.

A roof is only one surface in the room. If the walls are mostly old glazing with tired seals, heat will leave through them whatever sits above. Draughts around doors, a thin floor on a cold base and gaps at the wall junction all add up. Replacing the roof deals with the biggest single surface, but it is not the whole picture.

Added roof windows are a further limit. Part L sets roof windows at 1.4 and rooflights at 2.2, both well above the roof's 0.15, so fewer, better-placed units give light with less loss. See matching a conservatory roof to your house for how appearance and performance can be balanced.

Air leakage is easy to overlook. Warm air slips out through gaps at the eaves, around roof windows and along the wall junction, and carries heat with it. A tight, well-sealed build-up keeps that loss down as much as the insulation thickness does.

MyBuilder's conservatory roof guide (updated 2026) gives solid roofs a typical UK range of £5,000 to £10,000, against £3,000 to £8,000 for glass and £2,000 to £5,000 for polycarbonate. Structural reinforcement, when the frame needs it, is quoted at £500 to £2,000. These are national figures, and your quote after the survey covers the work your roof needs.

Until 31 March 2027, VAT on insulation fitted to a house is nil, a zero rate, while other roofing work is charged at the usual 20%. The quote shows each. Building control must also be applied to, since a solid roof alters the structure (Homebuilding and Renovating, 2023); see turning a conservatory into an extension if you plan a bigger change.

The point of the sourced ranges is to let you set a budget before anyone visits. A buyer comparing a polycarbonate roof at £2,000 to £5,000 with a solid one at £5,000 to £10,000 is really comparing two different rooms, and the extra spend has to be justified by how you will use the space.

Begin by asking how the room is used. A conservatory in daily use, heated in winter and sat in during summer evenings has more to gain than a storage room. Note its present state: whether the glazed roof drips with condensation, whether the room is shut off in cold months and whether it overheats in summer.

Then ask for the quote to state the insulation depth and the roof's U-value, to compare with the 0.15 target. We photograph the roof and frame at the survey. For the full service, costs and options, see conservatory roof replacement. If the frame needs work first, we discuss that with you, so you decide with the full picture.

A well-insulated roof works best alongside sensible use. Keep the room's heating on a thermostat or timer, not running flat out, and close the door to the house on the coldest nights if the room is used only occasionally. Draught-proof the doors and check the seals on the glazed walls, because a new roof will not offset a gap you can feel with your hand.

Furnishings matter as well. Curtains or blinds on the glazed walls hold warmth in the evening, and a rug on a tiled floor makes the room feel warmer underfoot. None of this replaces the work on the roof, but together these small things decide whether the room stays comfortable all year or only on mild days.