Do I Need Planning Permission for a Conservatory?

Most conservatories in England do not need planning permission. A conservatory is treated as a single-storey rear or side extension under Class A permitted development rights. As long as it stays within standard size, height and design limits, and does not cover more than half your curtilage, planning permission is not required. Deeper conservatories may still proceed via prior approval under the Larger Home Extension scheme rather than needing a full planning application.

• Single storey and within the standard rear extension depth: no more than 3 metres from the original rear wall (semi-detached or terraced) or 4 metres (detached)
• Maximum height no more than 4 metres, with eaves no more than 3 metres if the structure is within 2 metres of a boundary
• Does not extend beyond the side wall of the original house facing a highway
• Materials and appearance are similar to the existing dwelling
• No veranda, balcony or raised platform over 0.3 metres
• Less than half the curtilage is covered by the conservatory and all other additions and outbuildings combined
• Property is a house (not a flat or maisonette) with permitted development rights intact

Depth is measured from the original rear wall as it existed on 1 July 1948, or as the property was first built if constructed after that date. A conservatory added to a house that already had a rear extension must still be measured from the original 1948 wall, not from the more recent extension. This means a property with an existing 2-metre extension has only 1 metre of remaining permitted development depth left for a semi-detached or terraced house.

Conservatories deeper than the standard 3 m / 4 m limits — up to 6 metres from the original rear wall (semi/terraced) or 8 metres (detached) — do not qualify as standard permitted development. They require prior approval under the Larger Home Extension neighbour consultation scheme:

• You notify the council before starting work
• Affected neighbours have 21 days to comment
• The fee is around £120 (varies by authority)
• The council can only consider design and amenity impacts — it is a lighter process than full planning permission

This scheme does not apply on designated land (conservation areas, National Parks, AONBs, World Heritage Sites). On designated land, depths beyond the standard limits require a full planning application.

A conservatory on the side of a house follows different rules than a rear conservatory. Side extensions under Class A must not exceed half the width of the original house and must not be forward of the principal elevation. Side conservatories on designated land are not permitted development at all. A side conservatory on a corner plot facing a highway also needs careful assessment.

A conservatory may be exempt from building regulations approval if all three conditions are met:

• Floor area is less than 30 square metres
• It is separated from the rest of the house by external-quality doors (or glazed screens) with the same thermal performance as the external envelope
• It has its own independent heating system or no fixed heating

If any of these conditions is not met — for example, the doors between the conservatory and the house are removed to create open-plan living — building regulations approval is required for the whole conservatory. In practice, many homeowners choose to build to full building regulations standard regardless, as this produces a better-performing, more comfortable space.

Modern conservatories use thermally broken frames and double or triple glazing to improve comfort and reduce heat loss. If a conservatory is not exempt from building regulations (because the internal doors are removed), Part L energy efficiency requirements will apply, meaning the glazing, roof and walls must meet specific U-value standards. A solid insulated roof covering part of the conservatory is increasingly popular and can improve year-round usability but may affect the building regulations exemption status — check with building control before proceeding.

• Conservatory exceeds standard size or height limits and either exceeds the prior-approval depths or sits on designated land where that scheme is not available
• Property is a listed building (also requires listed building consent)
• Permitted development rights removed by an Article 4 direction
• Original planning permission conditions restrict extensions
• Conservatory is forward of the principal elevation facing a highway
• Property is a flat or maisonette

In conservation areas, rear conservatories within the standard 3 m / 4 m depths may still qualify as permitted development, but side conservatories are explicitly excluded. The Larger Home Extension prior-approval route is also unavailable in conservation areas. Materials and design will be scrutinised by the council if planning permission is needed, and traditional designs using timber frames and glazing often receive more sympathetic treatment than modern uPVC structures.

A uPVC conservatory (3–4 metres depth, standard size) typically costs £8,000–£20,000 supplied and installed. Aluminium or timber frame conservatories cost more: £15,000–£35,000. An orangery-style structure with a solid tiled roof section typically costs £20,000–£50,000. A householder planning application costs £258 if required. The Larger Home Extension prior approval fee is around £120.

Is a conservatory the same as an extension for planning purposes? Yes. GPDO 2015 treats a conservatory as an extension — the same Class A limits and conditions apply regardless of whether the roof is glass, polycarbonate, or solid.

Can I remove the glass roof and replace it with a solid roof? In most cases yes, but changing from a glazed roof to a solid insulated roof changes the thermal characteristics and may mean building regulations apply (particularly if the separation doors have been removed). Always check with your local building control body first.

Does a lean-to conservatory at the back of my house need planning permission? Probably not, as long as it is within the standard depth limits and other Class A conditions. Confirm with a free check using your specific address and dimensions.