The short answer
Replacing a conservatory with an extension gives you a permanent room, but it costs far more than a new roof and brings more rules. A new roof on a sound conservatory frame typically costs between £2,000 and £10,000 or more (MyBuilder, 2026). Keep the base and frame if they are sound; consider an extension if the room needs to work all year.
What a new roof gives you, and what it leaves alone
Putting a new roof on an existing conservatory changes what is over your head and nothing else. The base, the dwarf walls and the frame stay. MyBuilder's 2026 conservatory roof guide gives an average of about £4,500 and a range of £2,000 to £10,000 or more. By type, solid roofs sit at £5,000 to £10,000, glass at £3,000 to £8,000 and polycarbonate at £2,000 to £5,000. Structural reinforcement, where the frame needs it, adds £500 to £2,000.
A solid, insulated roof changes the way the room feels. It is quieter in rain, holds heat better and does not turn into a greenhouse in summer. It does not change the walls and windows, so if those are single glazed or draughty, the room stays a conservatory with a better lid. Our repair or replace guide sets out when a repair is still enough.
What knocking it down and extending involves
An extension replaces the conservatory with a built room: new foundations if the old base is not suitable, insulated masonry walls, a proper roof and windows chosen for the room rather than inherited from a kit. The result is a space that works on a January evening and sits comfortably in the house.
It is a building project rather than a roofing repair. You will normally need Building Regulations approval, and you should ask Stroud District Council's planning team early whether the work needs planning permission, since the outcome turns on the house, where it stands and how big the new room is. A listed house or a conservation area raises the stakes. In the Cotswolds National Landscape, which covers just over half of Stroud District, spend nothing on drawings until the planning team has answered.
Expect the project to include groundworks, a structural design, an architect or designer, and scaffold and builders for weeks rather than days. We are a roofing contractor, so we can talk you through the roof side of an extension and the roof you would be building; the walls, foundations and fit-out belong to a builder.
Cost and disruption, side by side
The table sets out what each route involves. Only the roof has a typical national range; an extension depends on its size, foundations and finish, so its cost is fixed by a builder's written quote.
| Question | New roof on the existing frame | Knock down and extend |
|---|---|---|
| Typical roof cost | £2,000 to £10,000+ (MyBuilder, 2026) | Part of a larger building budget |
| Rules | Solid roof needs Building Regulations; planning only if appearance changes significantly | Building Regulations; planning permission to check with the council |
| Walls and windows | Stay as they are | New, insulated |
| Time on site | Days to weeks, for the roof | Weeks to months |
The other rows describe how the work is organised. Get a written quote from a builder for the extension before you decide.
When the frame decides the question
The frame often settles it. Solid roofing weighs more than the sheets or glass it replaces. Homebuilding & Renovating cautions that frames designed for polycarbonate end up supporting a much heavier load. If a survey shows a bowed ridge, rotten timber, a cracked base or a frame that moves in wind, spending on a new roof over it makes little sense.
Other signs that tip things towards an extension: the room is too small for how you use it, the floor level does not match the house, or the room is used all year but never feels warm. A frame in sound condition, on the other hand, can usually carry a lightweight roof with reinforcement where needed, and that is a fraction of the disruption.
The page on conservatory roof sealants covers the lowest-outlay option, patching, and why it rarely buys long. If the roof is already failing and the frame looks poor, a quick fix is not the answer.
A middle route: a lantern or a glazed extension roof
Between the two sits the orangery style. A brick-built base under a flat or shallow roof topped with a glazed lantern in the middle gives a room that feels like part of the house but still has a lot of daylight. It can be built as a new extension or, with the right base, formed by rebuilding the upper part of an existing conservatory. Our page on orangery roof lanterns explains how they are glazed and what goes wrong with them.
Ask any builder how the new roof would be supported, how it meets the house wall and how water leaves it. Those three answers tell you more than a brochure does.
How we help you decide
A survey comes first. We photograph the existing roof and frame, go over the ridge, the gutter, the bars and the abutment with the house, and report what we find. If a new roof on the existing frame is the sensible route, you receive a written quote for it. If the frame is past saving, we tell you plainly, and we can price the roof of the new room once your builder has drawn the design.
When we fit a roof, we handle the consent paperwork, clear the site afterwards and give a written ten-year guarantee on our workmanship. The main service page on conservatory roof replacement sets out how we work.