The short answer
Replacing a polycarbonate roof with glass typically costs £3,000–£8,000; upgrading to a solid tiled roof (the ‘warm room’ conversion) typically costs £7,000–£15,000 depending on size. A roof replacement can be the single most cost-effective improvement to an older conservatory. See conservatory roof options and are conservatories too hot in summer for context.
Many conservatories built before 2010 have polycarbonate roofs — the lowest-cost material at the time, but now widely seen as a significant drag on comfort and energy performance. Replacing the roof is often the single most impactful upgrade to an existing conservatory, potentially transforming a space that is unusably hot in summer and freezing in winter into a room that is comfortable for much of the year. The cost depends heavily on the roof type chosen, the size of the conservatory, and whether the existing frame can support the replacement.
Roof replacement cost at a glance
- Polycarbonate to glass £3,000–£8,000 for medium conservatory (typical)
- Glass to solid tiled roof £7,000–£15,000 (typical)
- Polycarbonate to solid tiled £8,000–+£18,000 (typical)
- Build time 2–5 days for most replacements
- Planning implication Solid roof changes classification — check regs
- FENSA registration Required for glazed roof replacements
Why replace a conservatory roof?
The case for replacing a polycarbonate roof is strong. Polycarbonate transmits heat and cold much more directly than glass, meaning the conservatory overheats quickly in sun and loses heat rapidly in cold weather. It also discolours over time, reducing light quality, and is noisier in rain. Replacing with solar-control glass or a solid roof addresses all three problems. Even an existing glass roof may benefit from replacement if the glass is old single-glazed or early double-glazed units with poor U-values — modern roof glass is substantially better at limiting solar gain and heat loss.
Options and costs
| Replacement type | Small conservatory | Medium conservatory | Large conservatory |
|---|---|---|---|
| Polycarbonate to glass | £2,500–£5,000 | £4,000–£8,000 | £7,000–£12,000+ |
| Glass to glass (upgrade) | £2,000–£4,000 | £3,500–£7,000 | £6,000–£11,000+ |
| Any glazed to solid tiled | £7,000–£10,000 | £9,000–£15,000 | £13,000–£22,000+ |
These are typical illustrations only. The actual cost depends on the roof pitch, the frame condition (the new roof must be supported by a frame in good structural condition), access, and regional labour rates. Many companies offer a free site survey to confirm whether the frame will support a replacement roof before quoting.
Solid roof implications — planning and building regulations
A solid tiled roof replacement changes the conservatory’s legal classification. Once the roof is mostly solid rather than glazed, the structure no longer meets the definition of a conservatory for Building Regulations purposes and typically loses its Part L exemption. This means the replacement should comply with building regulations Part L, and in some cases a building control application is needed. Whether this applies in your specific case depends on whether the original conservatory had planning permission and how the replacement is specified — your installer or local building control office can advise. See conservatory building regulations for the detail.
FENSA and glazing compliance
If the replacement roof involves new double-glazed units — whether glass or polycarbonate — the work must comply with the building regulation requirements for replacement glazing and should be carried out by a FENSA-registered installer, or with a building regulations application. FENSA registration means the installer self-certifies compliance and registers the work with the local authority, which provides you with a FENSA certificate — important when you sell the property. A cash-in-hand or unregistered installer leaving no certificate can cause problems at conveyancing.
Is a roof replacement worth the cost?
For most conservatories with polycarbonate roofs, the answer is yes if you intend to use the space regularly — the transformation in temperature comfort and noise is immediate and significant. The calculation is more nuanced for older conservatories where the frame itself is beginning to show signs of age: if seals are failing, the frame is rattling and the base is cracking, it may be more cost-effective to replace the whole structure rather than invest in a roof upgrade. Get a professional assessment of the overall condition before committing to a roof-only replacement. See how to choose a conservatory company for guidance on finding a trustworthy assessor. This page provides general cost information only; prices are typical illustrations, not quotes.
Get roof replacement quotes
A roof replacement quote requires a site survey to assess the frame condition and measure the roof. Compare at least two quotes from FENSA-registered companies before committing.
Frequently asked questions
How much does it cost to replace a polycarbonate conservatory roof with glass?
Typically £3,000–£8,000 for a medium conservatory (20 m² approximately). The cost depends on roof size, the glass specification chosen, and whether any frame work is needed.
Can I replace my conservatory roof with a solid tiled roof?
Yes, but a solid roof changes the structure’s legal classification and may require building regulations compliance. The frame must also be assessed to ensure it can carry the additional load. Costs typically start around £8,000 for a small conservatory.
Does a roof replacement need planning permission?
A like-for-like glazed roof replacement does not typically need planning permission. A solid tiled roof may change the structure’s classification and could require a building regulations application. Check with your local planning authority or building control.
Is it worth replacing a conservatory roof?
For most conservatories with polycarbonate roofs, yes — the improvement in year-round comfort is significant. If the frame is also ageing, get an overall condition assessment before investing in the roof alone.
Sources & further reading
- Glass & Glazing Federation — conservatory roof materials, glazing specifications and replacement guidance
- FENSA — replacement glazing registration and compliance requirements
- GOV.UK — Building Regulations Part L (conservatory exemption) and replacement glazing requirements
- LABC — Local Authority Building Control guidance on solid roof conversions and building regulations
This is general information about conservatories and orangeries in the UK, not planning, structural, legal or financial advice. Costs are typical illustrations only and are not quotes for any specific project; actual prices vary with size, site conditions and your chosen installer.