Replace the conservatory roof or build an extension?

Anyone asking this question is usually fed up with one of three things: the room is too hot in summer, too cold in winter, or too noisy when it rains. All three are roof problems, and a new roof can fix them. If that is your list, an extension is a lot of building for a fault the roof can cure.

The other group has a different complaint. The room is too small, the layout does not work, the glazing is tired all over, or the walls and base are failing. Then the roof is only part of the problem, and putting a good roof on a poor structure is money spent in the wrong place. Write down what you want from the room before looking at either route, because the answer usually becomes obvious. Our page on turning a conservatory into a proper room covers what a roof alone can achieve.

A solid or high-performance glazed roof changes how the room feels. It holds heat in winter, keeps the sun off in summer and quiets the rain. It also gives you a ceiling that can take lights, and in a solid roof, roof windows to bring in daylight. It does not change the footprint, the floor, the doors or the walls.

That limit matters. If the room is the right size and the frame is true, nothing else has to move. The work is also far quicker and less disruptive than a build, with no digging, no new drains and little change to the garden. If you want an extra bedroom or a bigger kitchen, a roof will not provide it. Cost is a fair comparison point as well. Checkatrade gives around £10,000 as the UK average to replace a conservatory roof, within £6,300 to £18,225 or more (table last updated March 2026), and the written quote after our survey gives your own total.

An extension is a building project. It has its own design, foundations, walls, roof and services, and its own approvals. Building Regulations apply to the new structure, and depending on its size and position, planning permission may be needed too. For that, check with Arun District Council's planning team, or the council for your area, before anything is drawn up.

It takes much longer than a roof swap, and the garden is torn up in the process. The reward is a permanent room with the same standard of walls, floor and roof as the house, and freedom to plan the layout from scratch, including where the doors, radiators and sockets go. If your conservatory is small, badly placed or falling apart, that may be the right answer. The roofing part of an extension can be priced once the design exists, and our conservatory roof replacement service covers the roof alone.

Before choosing, someone has to look at what you have. Timber or aluminium that is plumb, dry and undamaged can carry a new roof for years. Rotten timber, corroded aluminium, a base that has moved or walls that have cracked all change the sums. A new roof on a failing structure will not last, and the fault will show again at the junctions.

We check the frame, the line where the roof butts the house and the base beneath, and take photographs of each. We also look for damp in the walls, for failed window seals and for any sign that the floor has moved, since those change the verdict. If the structure is good, the quote covers the roof alone. If it is not, you are told that too, even though it means a smaller job for us. Our foundations answer explains how the base is read, and the conservatory or orangery comparison helps if you are weighing a middle route.

Ask three questions. Is the size right? Is the structure sound? Is the room's only fault the weather inside it? Three yes answers point to a new roof. One no points to a closer look, and two or more suggest an extension deserves a proper quote.

Whichever way you go, ask for photographs of the problems and a written price. We provide both for the roof, and you will be told plainly if the better move is not to re-roof at all. Send a few photos of the room and the roof and we will book a survey.

It is worth keeping a record of what bothers you most. Note the times of year the room is unusable, any leaks or damp patches, and whether the doors and windows still close properly. Those notes make the survey sharper, and they help you compare the roof route fairly against whatever a builder proposes for an extension.