Quick Answer

The PD Rules for Conservatories

Conservatories are assessed as single-storey extensions under Class A of Schedule 2 to the GPDO 2015. The same rules that apply to a kitchen extension or rear addition apply to a conservatory. The only specific mention of conservatories in the rules exempts them from the requirement to use materials similar in appearance to the house.

This means a conservatory is permitted development provided:

• It is a single storey (the eaves must not exceed 4 metres, or 3 metres if within 2 metres of the boundary)
• It does not project more than 4 metres beyond the original rear wall (detached house) or 3 metres (semi-detached or terraced)
• Combined with other additions, it does not cover more than 50% of the original garden
• It is not positioned in front of the principal elevation (the front of the house)
• Materials broadly match the existing house (less relevant for glass/polycarbonate structures)
• The property is a house (not a flat) and is not listed

Size Limits Explained

The projection is measured from the original rear wall of the house — the rear wall as it was when the house was first built. If a previous owner has already extended the house, those extensions count and reduce your available PD allowance.

Height limits: the eaves of the conservatory must not exceed 4 metres. If the conservatory is within 2 metres of any boundary, the eaves height must not exceed 3 metres. The overall height must not exceed 4 metres (dual-pitched roof) or 3 metres (flat/mono-pitch roof).

Position and Location Rules

Conservatories can only be added to the rear or side of a house under permitted development — never to the front (the elevation that faces the road or public highway). A side conservatory is permitted development if it is single-storey and doesn’t exceed half the width of the original house.

The 50% garden coverage rule also applies: the conservatory footprint, combined with any other outbuildings and extensions, must not cover more than half the original garden area.

When You Always Need Planning Permission

• Listed buildings: Listed building consent is required for any works, including a conservatory
• Conservation areas: Standard PD rights may be reduced — check with your local council
• AONBs and National Parks: Side extensions require planning permission in these areas
• Flats and maisonettes: PD rights do not apply to flats
• Article 4 Directions: May remove Class A PD rights in certain areas
• Exceeding size limits: Any conservatory beyond the PD limits needs planning permission
• Planning conditions on the original property: Some new build homes have conditions removing PD rights

Building Regulations for Conservatories

Planning permission and Building Regulations are separate. Even if your conservatory is permitted development, Building Regulations may still apply.

The good news: conservatories are exempt from Building Regulations approval if all of the following are true:

• The conservatory is at ground level
• The floor area does not exceed 30 square metres
• It is separated from the house by external-quality walls, doors, or windows
• It has an independent heating system (or no heating at all)
• At least 75% of the roof and 50% of the walls are translucent (glass or polycarbonate)

What About Orangeries?

Orangeries have solid roofs with a central lantern light, rather than a fully glazed roof. Planning law treats them the same as a conservatory or extension — assessed under Class A PD rules. The same size limits, position rules, and exemptions apply.

However, orangeries with solid roofs typically do not meet the glazing threshold for the Building Regulations exemption. This means orangeries usually require Building Regulations approval regardless of size, because the roof is not 75% translucent.