In Northern Ireland, a conservatory is dealt with under Part 1, Class A of the Planning (General Permitted Development) Order (Northern Ireland) 2015, which sets dimension limits and extra restrictions in designated areas.

A separate planning system

Planning in Northern Ireland is governed by its own legislation and, in practice, dealt with by councils. The Planning (General Permitted Development) Order (Northern Ireland) 2015 applies to all land in Northern Ireland, and nidirect, the Northern Ireland government’s public information service, says that under permitted development rights you do not need planning permission for certain works provided they meet certain conditions, such as dimension restrictions when building an extension. It advises contacting your council planning office to check whether your work is allowed. This article summarises the Order’s Class A; it does not cover England, Wales or Scotland, which have their own rules covered in other guides on this site.

How a conservatory fits into Class A

Part 1, Class A of the Order permits the enlargement, improvement or other alteration of a dwellinghouse, subject to limits. The Order’s conditions expressly exclude “materials used in the construction of a conservatory” from the requirement that exterior materials match the existing house, which indicates that conservatories are dealt with as enlargements under Class A rather than as a separate category. If your proposal falls outside the limits, you would need to apply for planning permission.

The main size and position limits

Under Class A.1, development is not permitted if, as a result of the works, the ground covered by buildings within the curtilage (other than the original dwellinghouse) would exceed 50 per cent of the curtilage, excluding the original house’s footprint; or if the height of the enlarged part would exceed the highest part of the roof of the existing house, or its eaves would exceed the existing eaves; or if it would extend beyond a wall facing a road that forms the principal or a side elevation of the original house.

Single-storey extensions and boundaries

For an enlarged part with a single storey, development is not permitted if it extends beyond the rear wall of the original house by more than 4 metres for a detached house or 3 metres for any other house, exceeds 4 metres in height, or is within 3.5 metres of the curtilage boundary with a road opposite the rear wall. It is also not permitted if the enlarged part would be within 2 metres of any boundary and the eaves would exceed 3 metres, or if it would extend beyond a side elevation wall and exceed 4 metres in height or be wider than half the width of the original house. Multi-storey enlargements are subject to separate limits.

Designated areas and listed buildings

In a conservation area, World Heritage Site, area of outstanding natural beauty or National Park, Class A.2 says development is not permitted if it would include cladding the exterior with stone, artificial stone, pebbledash, render, timber, plastic or tiles; if the enlarged part would have more than one storey or exceed 4 metres in height; or if it would extend beyond a wall forming the principal or a side elevation. Class A.1 also excludes a dwellinghouse within the curtilage of a listed building unless listed building consent has previously been granted. Class A also does not permit development that includes an alteration to any part of the roof, a raised platform or deck, a basement, a chimney, flue or soil and vent pipe, or a microwave antenna.

When you must apply, and what to check

nidirect says you need to apply for planning permission to add to or extend a flat or maisonette, and to do anything not allowed by the original planning permission for your house, such as where a planning condition restricts alterations. It says permitted development rights are restricted in designated areas, listed buildings and conservation areas and areas of outstanding natural beauty, and that a council may force you to put things right if you build without the necessary permission. The Order can be amended, so check the current version and confirm with your council’s planning office before you build.

FAQs

Do I need planning permission for a conservatory in Northern Ireland?

Not necessarily. If it meets the Class A conditions it may be permitted development, but you must check the limits and any restrictions on your property, and confirm with the council.

Is a conservatory covered by the same rules as an extension?

The 2015 Order deals with conservatories within Class A, as its reference to materials used in the construction of a conservatory shows. Check with your council how it applies to your design.

Do building regulations also apply?

Permitted development concerns planning permission only. nidirect lists building regulations separately, so ask your council’s building control about them.

Bottom line

In Northern Ireland, a conservatory can be permitted development under Class A of the 2015 Order if it stays within the limits on curtilage coverage, height, rear projection and distance from boundaries, with tighter rules in conservation areas and other designated land, and planning permission needed to extend a flat or maisonette. Confirm your case with your council before you commit. This is general information, not planning advice.

Sources

This guide draws on the following primary sources, current as of 20 September 2026:

• legislation.gov.uk, “The Planning (General Permitted Development) Order (Northern Ireland) 2015”
• nidirect, “Planning permission – when to apply”

Related guides

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.