Millions of UK homes have conservatories that were built in the 1980s and 1990s — typically on minimal foundations, with polycarbonate roofing that is cold in winter, unbearably hot in summer, and deafeningly loud in rain. Refurbishing rather than demolishing and rebuilding is usually significantly cheaper and quicker, and modern insulated solid roof systems have transformed what a conservatory can be as a usable living space.
In 2026, a straightforward polycarbonate-to-solid-roof upgrade on a typical 12–15 m² conservatory costs £5,000–£12,000. A full refurbishment — new roof, new dwarf walls, new glazing, underfloor heating, electrical upgrade, and internal decoration — runs £15,000–£30,000.
Conservatory Refurbishment: Scope Options
Option 1: Roof Replacement Only (£5,000–£18,000)
The single most impactful upgrade. Options:
| Roof Type | Typical Cost (12–15 m²) | Thermal Performance | Notes |
|---|---|---|---|
| Polycarbonate (16 mm twin-wall) | £800–£1,500 | Poor (U ~1.8 W/m²K) | Like-for-like replacement only |
| Self-cleaning solar glass | £3,000–£6,000 | Moderate (U ~1.0) | Reduces heat gain; still cold in winter |
| Solid insulated (tiled/slate) | £6,000–£12,000 | Good (U ~0.18) | Requires structural check |
| Flat roof (felt or GRP) | £2,500–£5,500 | Moderate (with insulation) | Budget option; less aesthetic |
| Aluminium lantern roof | £5,000–£15,000 | Good (modern glazing) | Premium appearance |
Solid insulated roofs add significant weight. Before installing one, a structural engineer (£400–£900) must confirm the existing frame and foundations can take the load. Many older conservatories require either column upgrades or re-casting of the dwarf wall footings.
Option 2: Glazing Replacement (£2,000–£8,000)
Older conservatories often have single-glazed or early double-glazed units that have failed (misted between panes) or have poor thermal performance. Replacing the side panels with modern argon-filled, low-E double or triple glazing (typical U-value 1.0–1.2 W/m²K) dramatically reduces heat loss.
- Per double-glazed unit (standard): £150–£350 supply and fit
- Per triple-glazed unit: £200–£450 supply and fit
- Full side glazing replacement (12 panels): £2,500–£6,000
Option 3: Flooring (£800–£4,000)
Old tiled or carpet floors often suffer from damp, particularly if the conservatory was built on a shallow screed over minimal insulation. Replacement options:
- Tile or porcelain over new DPM and insulation: £40–£80/m²
- Luxury vinyl tile (LVT): £25–£50/m²
- Engineered hardwood: £50–£100/m²
- Underfloor heating (electric mat, wet system): add £30–£70/m² to any of the above
Option 4: Heating and Ventilation (£1,500–£5,000)
An unheated or poorly heated conservatory is unusable for 5–6 months of the year. Options:
- Electric panel heaters: £200–£600 per heater, simple to add
- Wet radiator (extending existing system): £500–£1,200 per radiator including pipework
- Underfloor heating (wet system): £800–£2,500 depending on area
- Air source heat pump (ASHP) split unit for heating and cooling: £1,500–£4,000 installed
Ventilation is equally important. Roof vents, opening ridge vents, or a through-the-wall MVHR extract will prevent condensation forming on cold glazing.
Option 5: Electrical Upgrade (£600–£2,000)
Most older conservatories have an inadequate spur off the house ring main with no RCD protection. A proper installation should include:
- Dedicated circuit from consumer unit
- RCD or RCBO protection
- Sufficient double sockets (minimum 4 for a typical conservatory room)
- Lighting circuit with dimmer capability
- External waterproof sockets if garden access is needed
Full Refurbishment Cost Example
For a typical UK lean-to conservatory, approximately 12 m² (4 m × 3 m):
| Element | Low | High |
|---|---|---|
| Structural survey | £400 | £900 |
| Solid insulated tiled roof | £5,500 | £10,000 |
| Side glazing replacement (8 panels) | £2,000 | £4,500 |
| Dwarf wall repair/repointing | £300 | £800 |
| Floor (tiled + UFH electric mat) | £1,200 | £2,800 |
| Electrical upgrade | £700 | £1,800 |
| Plastering/boarding (ceiling) | £600 | £1,200 |
| Decoration | £500 | £1,200 |
| Total | £11,200 | £23,200 |
Planning Permission
Conservatory refurbishment — even a full roof replacement — is generally permitted development and does not require planning permission in England, provided:
- The conservatory itself was built with permitted development rights or with planning consent
- The refurbishment does not increase its footprint or height
If the property is listed or in a conservation area, listed building consent or planning permission is likely required even for roof changes.
A solid roof conversion on a conservatory may, however, require Building Regulations approval because a new roof is a regulated element. The position varies by local authority and by the proportion of glazing retained. If the roof has less than 75% glazing/translucent material, the conservatory exemption from Part L of the Building Regulations no longer applies — you will need to comply with Part L energy targets. Always confirm with your Local Authority Building Control.
Conservatory vs. Extension: When to Knock Down and Rebuild?
Refurbishment makes sense when the frame is structurally sound (aluminium or UPVC in good condition) and the footprint and layout work. Consider a full demolition and rebuild if:
- The frame is badly corroded or deformed
- The foundations are inadequate for any significant roof load
- You want to fundamentally change the size or layout
- You want the room to be thermally indistinguishable from the rest of the house (a full extension achieves this better than any refurbishment)
A like-for-like extension rebuild costs £1,500–£2,500/m², so a 12 m² conservatory rebuild is £18,000–£30,000 versus a refurbishment at £11,000–£23,000. The gap is real but not enormous, and for complex structural situations a new-build extension may actually represent better value over a 20-year horizon.
