Conservatory roof replacement: the complete guide

Signs it is time to replace your roof

• Too hot in summer, too cold in winter — the classic sign of an uninsulated glass or polycarbonate roof.
• Deafening rain noise — old polycarbonate can hit 80+ decibels in a downpour.
• Leaks, draughts or condensation — failing seals and cold surfaces breeding damp or mould.
• Fading furniture and glare — too much uncontrolled solar gain.
• A room you never use — and want back as a year-round space.
• Selling soon — a properly certified solid roof is a genuine selling point.

Your options and what they cost

You can re-roof in solid/tiled, glass, hybrid, insulated panels or polycarbonate. The solid warm roof is the most popular — extension-grade warmth and a plastered ceiling — while a hybrid keeps more light. See the full roof options comparison and typical 2026 replacement costs (from around £2,000 for polycarbonate to £6,500–£15,000 for a solid roof). Our cost calculator gives an indicative estimate in under a minute.

How the installation works

A proper solid roof replacement follows five stages:

1. Survey & structural assessment — a surveyor checks the frame, brickwork and foundations, and confirms the frames have steel reinforcement (or adds support posts).
2. Roof removal & stabilising — the old panels and frame are removed and a structural ring beam is fixed to the top of your existing windows.
3. New structural frame — engineered rafters and ridge go up, boarded and sealed with a breathable membrane and lead flashing, then clad in lightweight tiles — usually watertight within 2–3 days.
4. Insulation & finishes — rigid insulation between the rafters, a sealed vapour-control layer, then plasterboard and a skim coat for a smooth vaulted ceiling.
5. Inspection & sign-off — building control inspects the insulation and structure and issues the completion certificate.

Will it fit your existing frame?

Usually yes — but it matters. A solid roof is much heavier than polycarbonate, so the vertical frames need internal steel reinforcement and the foundations need to be sound. Frames fitted before about 2000 sometimes need steel “goalpost” supports (especially over wide bi-fold doors), which a survey will confirm. A good installer checks this properly rather than assuming.

Permissions & paperwork

A solid roof normally needs building control approval (but not planning permission), and cannot be certified by FENSA. Keep the building control completion certificate for when you sell. See the full building regulations guide.

Choosing an installer — and avoiding the cowboys

The biggest risk in this trade is the “cladover”: leaving the old roof in place and cladding over and under it. Your old frame was never built for that weight, so cladovers sag, fail building control, and cause sale problems later. Protect yourself:

• Insist on a proper engineered warm-roof system (Guardian, Ultraframe, SupaLite, Leka and similar).
• Check for accreditations — TrustMark, NFRC, CPA, Certass — and an insurance-backed guarantee.
• Make sure building control sign-off and the completion certificate are included.
• Get the warm-roof build (sealed vapour layer) in writing to avoid condensation problems.

Local authority guidance also warns that wrapping a new covering around an existing lightweight roof can overload the structure. Read the LABC householder guide to re-roofing conservatories, then require structural suitability and the proposed build-up in writing.

When you are ready, our free calculator gives you an indicative range. You can also request one local installer introduction, subject to coverage and availability.