Conservatory replacement extensions

Conservatory replacement means taking down an old conservatory and building a solid, insulated extension in its place, with proper walls, an insulated roof and modern glazing. The result is a room that is comfortable in winter and summer rather than one you avoid for half the year.

It is sometimes possible to reuse the existing base, but conservatory foundations are often too shallow for a solid extension. We dig trial holes before confirming the price so there are no surprises once the old structure is down.

What is included

• Removal and disposal of the old conservatory
• Trial holes to check the existing foundations
• New or upgraded foundations
• Insulated walls and roof to current regulations
• Glazing and doors to suit the new room
• Opening widened into the house if wanted

Who it suits

• Conservatories that are too hot or too cold
• Older uPVC conservatories near the end of their life
• Homes where the conservatory sits unused

Design advice

A replacement is a chance to rethink the shape. Many conservatories are oddly proportioned; for a similar cost the new room can often be squarer, wider or better connected to the kitchen.

How much does it cost?

National guide prices including VAT at 20%. Build cost only; design, structural and council fees are extra. Your area page shows prices adjusted for your region.

Includes removal of the old conservatory. Reusing existing foundations is only possible after investigation.

Planning rules across the UK

England

In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.

Wales

In Wales a single-storey rear extension can usually project up to 4 m beyond the rear wall without a planning application, if it is no more than 4 m high, keeps eaves to 3 m and overall height to 4 m within 2 m of a boundary, and covers no more than half the land around the original house. Wales has no larger home extension prior approval scheme.

Scotland

In Scotland, householder permitted development rules (Class 1A for single-storey ground-floor extensions and Class 1B for extensions of more than one storey) allow some smaller extensions without a planning application, within limits on depth, height and distance from the boundary. Conservation areas and listed buildings are more restricted. Separately, almost every extension needs a building warrant from the council before work starts.

Northern Ireland

In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.

Building regulations and neighbours

Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.

In England and Wales, if the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations. Scotland and Northern Ireland have no Party Wall Act.

Questions about conservatory replacement extensions