Do I Need Planning Permission for a Conservatory? | UK Rules 2026

01

When a Conservatory Is Permitted Development

A conservatory is treated the same as any other single-storey rear extension under the GPDO. Under Schedule 2, Part 1, Class A, you can build a conservatory without planning permission if it meets ALL of the following conditions:

Size Limits

• Maximum depth from the rear wall: 4 metres for detached houses, 3 metres for semi-detached and terraced houses (or up to 8m/6m under the larger home extension scheme with prior approval)
• Maximum height: 4 metres overall
• Eaves height: no higher than the eaves of the existing house (A.1(d)). There is no general 3-metre eaves cap; the 3-metre limit applies only within 2 metres of a boundary (see below)
• No more than half the garden (the area of land around the "original house") is covered by extensions and outbuildings combined

Position Rules

• Must not extend beyond the principal elevation (front of the house) or a side elevation that faces a highway
• Side extensions must be single storey with a maximum width of half the width of the original house
• If any part is within 2 metres of a boundary, its eaves must not exceed 3 metres (A.1(i))

Materials and Design

• The Class A condition that materials must be similar in appearance to the existing house expressly excludes conservatories: it covers exterior work "other than materials used in the construction of a conservatory" (A.3(a)). So glass and uPVC frames are fine under permitted development
• No verandas, balconies, or raised platforms (over 300mm)

"Original House" Matters

The "original house" means the house as it was first built, or as it existed on 1 July 1948 (whichever is later). Any previous extensions count against your permitted development allowance. If a previous owner added a 2-metre rear extension, you only have 1-2 metres left before hitting the limit.

02

The Larger Home Extension Scheme

Since 2013, the government has allowed larger single-storey rear extensions under a prior approval process (often called the "neighbour consultation scheme"). This allows:

• Up to 8 metres deep for detached houses
• Up to 6 metres deep for semi-detached and terraced houses

This isn't automatic permitted development — you must notify the council, and they must consult your immediate neighbours. If neighbours object, the council decides whether the impact on the amenity of adjoining premises is acceptable (A.4). The fee is £249 (from 1 April 2026; fees rise each April).

This scheme applies to conservatories just as it applies to any other single-storey rear extension. It's been made permanent (it was originally temporary). It is not available on article 2(3) land (conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites) or on a site of special scientific interest (A.1(g)), so there the limit stays at 4m/3m.

03

When You Need Planning Permission

You'll need a full planning application for a conservatory if:

• It exceeds the permitted development size limits
• It's at the front or side (facing a highway) of the house
• The property is a listed building (strictly, Class A has no listed-building exclusion, but works affecting a listed building's character need listed building consent whether or not planning permission is needed)
• Permitted development rights have been removed (by planning condition or Article 4 direction)
• The house is a flat or maisonette
• It would cover more than half the garden
• The property has already used its PD allowance with previous extensions

Conservation Areas

In conservation areas, you still have permitted development rights for rear conservatories, but with additional restrictions:

• Cladding the exterior is not permitted development
• Some areas have Article 4 directions removing PD rights entirely
• The design and materials may face more scrutiny if you need to apply

04

Building Regulations

This is where many homeowners get confused. Even if your conservatory doesn't need planning permission, it may need building regulations approval.

When Building Regulations Apply

A conservatory is exempt from building regulations if ALL of the following are true:

• It is at ground level
• The floor area is less than 30 square metres
• The glazing complies with safety glazing requirements (Part K/N)
• There is a separating wall and door between the conservatory and the main house (the existing external wall is kept or a new separation is created)
• Any fixed electrical installations comply with Part P
• The heating system is independent from the main house (or extends the existing system with separate temperature controls)

If you remove the wall between the house and the conservatory to create an open-plan space, the building regulations exemption is lost, and the conservatory must comply fully — including structural, thermal, and energy performance standards.

The Wall Removal Trap

Many people build a conservatory under the building regulations exemption, then knock through the separating wall later. This technically means:

• The conservatory is no longer exempt from building regulations
• The whole structure needs to meet current standards (thermal performance, structural integrity, foundations)
• A retrospective building regulations application may be needed

Building control officers increasingly check for this, especially during property sales.

05

Conservatory vs Extension: What's the Difference?

For planning permission purposes, there's no difference — a conservatory is just a type of extension. The same permitted development rules apply whether you're building a brick extension or a glass conservatory. If you're also considering other additions, the Class D rules for porches are separate from these extension rules, and garages follow either Class A (attached) or Class E outbuilding rules depending on whether they're connected to the house.

For building regulations, conservatories have the exemption described above (if conditions are met), while regular extensions must always comply with building regulations.

The key distinction is usually about the proportion of glazing:

• A conservatory typically has at least 50% of its wall area and 75% of its roof area glazed
• An orangery has more solid walls with a glazed roof lantern
• A standard extension has conventional walls and roof

All three follow the same planning rules, but the building regulations implications differ.

06

Party Wall Considerations

The Party Wall etc. Act 1996 applies if your conservatory involves any of these, each with its own notice period:

• A new wall on the boundary line: at least one month's notice (s1(2) and (5))
• Work to an existing party wall, such as building against it and cutting in a flashing (s2(2)(j)): a party structure notice at least two months before work starts (s3(2)(a))
• Excavating within 3 metres of a neighbour's building to below the level of its foundations, or within 6 metres where the dig would cut a 45-degree line drawn down from them: at least one month's notice (s6)

If a neighbour does not consent in writing within 14 days to a party structure or excavation notice, a dispute is deemed to arise (s5, s6(7)). You then either agree one surveyor or each appoint your own (s10(1)), and the surveyors make an award settling how and when the work is done (s10(12)). For a new wall on the line of junction, if the neighbour does not consent you may only build it wholly on your own land, at your own expense (s1(4)).

This is separate from both planning permission and building regulations. Failure to serve notice doesn't make the conservatory unlawful, but it leaves you open to an injunction or damages claim.

07

Foundations and Ground Conditions

Conservatories need proper foundations — typically strip foundations or a concrete slab. The depth depends on:

• Soil type — clay soils need deeper foundations (often 1 metre+) due to shrinkage
• Trees nearby — tree roots can cause subsidence; foundations may need to be deeper (sometimes 2-3 metres near large trees)
• Drainage — you may need to reroute drains that run under the conservatory footprint

This is a building regulations and practical construction issue, not a planning issue, but it significantly affects cost.

08

Costs

A conservatory typically costs:

• Budget UPVC conservatory: £5,000-£12,000
• Mid-range conservatory: £12,000-£25,000
• High-end orangery/conservatory: £25,000-£50,000+
• Planning application fee (if needed): £548 for a householder application (MHCLG fee schedule, from 1 April 2026; fees rise each April), with decisions typically within 8 weeks
• Building regulations application (if needed): £200-£500
• Party wall surveyor (if needed): the surveyors decide in the award who pays their costs (s10(13)); get a quote rather than relying on a typical figure

09

Tips for Avoiding Problems

1. Measure from the original rear wall — not from any previous extensions
2. Check previous extensions — they count against your PD allowance
3. Keep the separating wall if you want the building regulations exemption
4. Serve party wall notices early — delays here can delay your whole project
5. Consider a lawful development certificate if you want written confirmation the conservatory is permitted development
6. Check your local council's approach — some are stricter than others on enforcement. Check your local council's planning portal, e.g. Sheffield or Liverpool, for local restrictions
7. If a conservatory has already been built beyond the permitted development limits, retrospective planning permission is a viable option — submit an application before selling