A conservatory beside a house, or wrapping round the corner, is judged against both the rear-extension and the side-extension limits. The Order and the government’s technical guidance explain how.
In this guide
Most guidance on permitted development conservatories concentrates on depth at the back of a house. A conservatory that extends beyond a side wall, fills the gap between side and rear, or sits on a corner plot faces extra limits in England. This guide explains those limits using the Town and Country Planning (General Permitted Development) (England) Order 2015 and the government’s householder technical guidance. It is general information, not planning advice, and the local planning authority has the final say.
The side-wall limits
Under Class A, Part 1, Schedule 2 to the Order, development is not permitted where the enlarged part would extend beyond a wall forming a side elevation of the original dwellinghouse and would exceed 4 metres in height, have more than a single storey, or be wider than half the width of the original dwellinghouse. The technical guidance says a side elevation wall is any wall that cannot be identified as a front or rear wall, so a house often has more than two. The width of the original house is calculated at its widest point.
“Original” has a specific meaning. The guidance defines it as the building as it existed on 1 July 1948, or as built if constructed after that date, so earlier extensions are not counted when working out half the width. A conservatory counts as an enlargement under Class A and must meet these limits like any other extension. The wider framework is explained in the guide to permitted development rights and conservatories.
Corner plots and walls that face the road
A separate limit applies at the front. The Order says development is not permitted if the enlarged part would extend beyond a wall that forms the principal elevation of the original house, or that fronts a highway and forms a side elevation. The guidance explains that “extend beyond a wall” covers not only the area directly in front of the wall but also the area in front of a line drawn from the end of the wall to the boundary of the property.
On a corner plot, whether a side wall fronts a highway depends on factors such as the angle between the wall and the road and the distance between them. The guidance says that if the angle is more than 45 degrees the elevation will not normally be considered to front a highway, and that a substantial distance, or land in different ownership or use in between, makes it unlikely.
Wraparound conservatories
Where an extension fills the area between a side elevation and a rear wall, the guidance says the limits for both apply. A single-storey extension of this kind must:
- extend no more than 4 metres beyond the rear wall (3 metres for a house that is not detached), or up to 8 metres (6 metres for other houses) under the larger-extension notification route, which is unavailable on article 2(3) land and sites of special scientific interest;
- be a single storey and no more than 4 metres high; and
- not exceed half the width of the original house at its widest point.
The guidance warns that an extension under half the width can still fail if it projects too far beyond a second, stepped rear wall. Where the original rear wall is stepped, each wall counts as the rear wall for these tests. The notification route for deeper extensions is described in the guide to larger single-storey rear extensions.
Earlier extensions count towards the limits
Paragraph A.1(ja) provides that any total enlargement, meaning the new part together with any existing enlargement it will be joined to, must stay within the limits for front, rear and side walls. The guidance uses a staged example. A side extension that is under half the width of the house is permitted by itself. Adding a rear extension later can push the total width across the widest point past half the original width, and the rear extension then needs a planning application.
The overall ground coverage test is separate and is explained in the guide to the 50% garden rule.
Boundary height, materials and protected areas
Three further provisions matter at the side of a house. If any part of the enlarged section is within 2 metres of the boundary of the curtilage, the eaves must not exceed 3 metres. The materials condition, which requires similar-looking exterior work, excludes materials used in the construction of a conservatory. On article 2(3) land, which includes national parks, areas of outstanding natural beauty, conservation areas and World Heritage Sites, paragraph A.2 says development is not permitted if it would extend beyond a wall forming a side elevation. See the guide to article 2(3) land for the wider restrictions there.
FAQs
Can a conservatory be built beside a house without planning permission?
In England it can be, provided it is a single storey, no more than 4 metres high, no wider than half the width of the original house, and does not breach the other Class A limits.
Does a corner plot stop a side conservatory?
Not automatically. A side wall that fronts a highway cannot be extended in front of, but the guidance says an angle of more than 45 degrees or a substantial distance from the road means the wall will not normally be treated as fronting it.
Do previous extensions affect a new conservatory?
Yes. The total enlargement, including any existing extension that the new part joins, must stay within the limits.
The bottom line
A conservatory at the side of a house in England must be single storey, no higher than 4 metres and no wider than half the original house, and it cannot extend in front of the principal elevation or a side wall facing the road. Wraparound designs must satisfy the rear and side limits together, and earlier extensions count towards the totals. Checking the measurements against the original house, and asking the council for a lawful development certificate if in doubt, is the safest route.
Sources
This guide draws on the following sources, current as of 9 October 2026:
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, Class A (legislation.gov.uk)
- Permitted development rights for householders: technical guidance, Ministry of Housing, Communities and Local Government (gov.uk)
Related guides
Permitted development
The 50% garden rule
Protected areas
Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.