Maintaining Your Property

Conservatories: planning permission and Building Regulations

A conservatory is one of the quicker ways to gain living space and add value to a home. The catch is the paperwork: planning permission, or proof it was not needed, and Building Regulations approval. If either is missing it usually comes to light when you sell, as a buyer's solicitor asks for documents that do not exist, and it can delay or derail the sale.

See The Rules By Nation

Rear elevation of a house with a glazed single-storey conservatory extension

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Two separate consents, three sets of national rules.

Planning permission and Building Regulations are separate consents, and England and Wales, Scotland and Northern Ireland each set their own rules for both. Check which nation's rules cover your property before you order anything or sign a contract.

Two approvals

Planning permission and Building Regulations are separate consents. A conservatory can be permitted development and still need Building Regulations attention.

Three regimes

England and Wales, Scotland and Northern Ireland each set their own limits on size, height, position and glazing.

1 July 1948

The 'original house' means the property as first built, or as it stood on 1 July 1948 if older — earlier extensions count against your allowance.

Planning in England and Wales

Conservatories follow the rules for single-storey extensions.

In England and Wales, a conservatory is treated as a single-storey extension for planning purposes, and Building Regulations are a separate question covered below. Permitted development rights let many conservatories go ahead without a planning application, provided every one of these limits is met:

Land coverage: additions and outbuildings together must not cover more than half the land around the original house.
Rear projection, single storey: up to 8m on a detached house, 6m on any attached house.
Rear projection, more than one storey: up to 3m, and not within 7m of the boundary opposite that rear wall.
Forward of the building line: nothing may project beyond the principal elevation, or beyond a side elevation fronting a highway.
Height, single-storey rear extension: 4m maximum overall.
Height, generally: no higher than the highest part of the existing roof, with eaves and ridge no higher than the existing house.
Near a boundary: eaves height capped at 3m where the extension sits within 2m of a boundary.
Side extensions: single storey only, 4m maximum height, and a width of no more than half the original house.
Roof pitch: on anything above single storey, it must match the existing house.
Not permitted: verandas, balconies and raised platforms.
Designated land: no side extensions, no rear extensions above single storey and no external cladding under permitted development.

What counts as the 'original house'

For permitted development, the original house means the house as first built or, for anything older, as it stood on 1 July 1948. Extensions added by earlier owners use up the same allowance, so check the property's history rather than assume the full allowance is still available.

What counts as 'designated land'

Conservation areas, World Heritage Sites, National Parks, the Broads and Areas of Outstanding Natural Beauty all count as designated land, and permitted development rights are more restricted on each of them.

Conservatories to the side

Most conservatories go on the back of a house, but side ones are common. A side conservatory needs planning permission if it has more than one storey, stands taller than 4m, or is more than half as wide as the original house. Meet every permitted development limit and no application is needed.

Building Regulations and alterations

Heating and roof changes are what usually move the goalposts.

The conservatory exemption is narrower than most owners expect. Two fairly ordinary decisions — how the space is heated, and what the roof is made of — decide whether you are dealing with a conservatory or, in the eyes of the regulations, a single-storey extension.

Building Regulations and heating

In England and Wales, linking a conservatory to the house's central heating brings it under Building Regulations. To keep the exemption, it needs its own heating with separate controls, such as a standalone electric heater.

Replacing a glass roof with tile or slate

Swapping a glazed roof for tiles or slate is a popular upgrade, but in regulatory terms it turns the conservatory into a single-storey extension. The conservatory exemption then falls away and the structure has to meet Building Regulations.

Restrictive covenants

A restrictive covenant in the title deeds can prohibit building on the house or its grounds, whatever planning rules allow. If one appears during a sale or purchase, ask your solicitor how it affects you.

Planning in Scotland

Permitted development covers single-storey ground floor enlargements.

In Scotland, permitted development covers enlarging a house with a single-storey ground-floor extension, along with any roof changes the work needs. That takes in the usual rear extension as well as conservatories, carports, canopies and covered areas, whether walled or open. What follows depends on the number of storeys.

Single-storey extensions

For a single-storey extension, no planning application is needed when:

Position: to the rear of the house.
Projection: no more than 3m from the rear wall on a terraced house, or 4m on any other type.
Eaves height: no more than 3m where the wall meets the roof.
Overall height: no more than 4m, measured to the top of any sloping roof.
Ground coverage: buildings must not cover more than half the curtilage — the ground around the house.
Floor area: no more than half the original floor area of the property.
The property is neither listed nor within a conservation area.

Multi-storey extensions

For an extension of more than one storey, no planning application is needed when:

Position: to the rear of the house.
Boundary distance: at least 10m between the extension and the boundary of the curtilage.
Height: no higher than the existing house, disregarding chimneys.
Ground coverage: no greater footprint than the original house, and no more than half the curtilage.
The property is neither listed nor within a conservation area.

Certificate of Lawfulness and building warrants

An extension that meets these conditions needs no planning permission, but you should still get a Certificate of Lawfulness from the planning department as proof. Separately, a building warrant must be in place before work starts on any extension and on some conservatories. Fall outside the conditions and you need to apply for planning permission.

Building Regulations in Scotland

75% of the roof area and 50% of the external wall area, or
95% of the roof area and 35% of the external wall area.

Adding a radiator needs no planning permission, but plumbing it into the house's central heating brings the conservatory under Building Regulations, because the law expects a conservatory to be heated independently.

Planning in Northern Ireland

Most installations are permitted development, with conditions.

In Northern Ireland, most conservatories count as permitted development. You can build a conservatory or single-storey extension without a planning application when:

It is no more than 4m high, reduced to 3m within 2m of a boundary.

It takes up no more than half of the garden.

Its highest point sits below the eaves of the house roof.

Conservatories and sunrooms rarely need planning permission in Northern Ireland, but these rules still apply:

An attached conservatory is treated as an extension, so the single-storey extension conditions apply to it.
Rear extension depth allowances have been relaxed, permitting up to 6m on an attached house and 8m on a detached house without a planning application.
A rear conservatory that adds more than 40sqm to the original footprint requires planning permission.
A conservatory positioned to the side of the dwelling requires planning permission whatever its size.
A front conservatory can fall within permitted development, provided buildings and additions still cover no more than 50% of the land around the original house.
Flats, maisonettes, converted houses and listed buildings sit outside these allowances and should be assumed to need permission.
Building Regulations exemption depends on the structure being a ground-level extension of no more than 30sqm floor area.
Translucent materials must make up at least three-quarters of the roof and half the external walls, and the glazing must meet safety requirements.
A thermal break must be retained between the house and the conservatory, and heating cannot be extended into it without an application.
Fail any of these conditions and the structure is an extension in law, with the full Building Regulations applying to it.

Anything outside these limits needs Building Regulations approval.

Surveyor reviewing property paperwork and inspection notes for an extension

Buying, selling or altering

Missing paperwork is a sale problem, not just a planning one.

Conservatories are one of the most common places where consents and reality drift apart. Where the permissions are not in place, the issue tends to surface at the worst possible moment.

How it usually goes wrong

A buyer's solicitor asks for the planning consent or Building Regulations completion certificate and it does not exist.
Indemnity insurance is offered as a fix, but the lender or buyer will not accept it.
A retrospective application is needed mid-transaction, adding weeks to an agreed timescale.
The structure has to be altered or removed to meet the rules, which is far more expensive after the event.

Paperwork against the structure

We look at what has actually been built and whether it matches the permissions and certificates on file. Missing planning consent or Building Regulations approval is one of the more common reasons a sale runs into trouble late on.

Condition of the junction with the house

Conservatories are often where damp, condensation and water ingress first show up — at the abutment with the main wall, around the flashing and where rainwater is discharged. We inspect the detailing rather than the sales brochure.

Roof conversions and thermal separation

Where a glazed roof has been replaced with tile or slate, or the doors between house and conservatory have been removed, the structure may no longer be exempt. We flag it so it can be regularised before it becomes a sale problem.

Common questions

Conservatories at a glance.

Do I need planning permission for a conservatory?

In England and Wales, conservatories fall under the same planning rules as single-storey extensions and are usually permitted development, provided the size, height, position and land coverage limits are met. Building Regulations are still required. Scotland and Northern Ireland set their own conditions, so the answer depends on where the property is.

When is a conservatory exempt from Building Regulations?

In England and Wales, the conservatory must be heated independently of the house, with its own controls, such as a standalone electric heater. Plumb it into the main heating system and Building Regulations apply.

Does replacing a conservatory roof with tiles need approval?

Yes. A tiled or slate roof turns a conservatory into a single-storey extension in regulatory terms, so the exemption is lost and the structure must comply with Building Regulations.

What does 'original house' mean for permitted development?

It means the house as first built or, if older, as it stood on 1 July 1948. Extensions by previous owners count against the allowance, so check the history even if you have never built anything yourself.

How is a conservatory defined in Scotland?

Under the Building (Scotland) Act 2003, a conservatory is attached to a house and thermally separated from it by a door and other elements, with translucent glazing (frames included) making up at least 75% of the roof and 50% of the external walls, or 95% of the roof and 35% of the walls.

Can I put a radiator in a conservatory in Scotland?

Yes, a radiator needs no planning permission. But plumbing it into the house's central heating brings the conservatory under Building Regulations, because the law expects a conservatory to be heated independently.

What happens if a conservatory was built without the right permissions?

Problems usually surface during a sale, when a buyer's solicitor asks for consents that do not exist. Options include a retrospective application, a certificate of lawfulness or indemnity insurance, but not every lender or buyer accepts them. Identifying the gap early is far cheaper than discovering it at exchange.

Will a survey tell me whether a conservatory is compliant?

A survey reports on the construction and condition of what has been built, and flags where the structure looks like it needs consents that may not be in place, so you know what to ask your solicitor to confirm. The legal position is confirmed through the conveyancing process and the local authority records.

Any questions?

Have a conservatory checked before it becomes a problem.

We inspect what has actually been built, how it meets the main structure and where the detailing is likely to cause damp or heat loss — and flag where the consents look incomplete, so your solicitor knows what to confirm. Useful whether you are buying, selling or planning alterations. For new work, see our plans and drawings and building regulations services.

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