Extensions
Conservatory Permitted Development: Do You Need Planning Permission? (2025)
Most conservatories can be built without planning permission. But the size limits, position rules, and property type all matter. Here’s the complete picture.
⏱ 5 min read
📅 Updated June 2025
🏠 England only
Quick Answer
In most cases: No planning permission needed
A conservatory is treated like any other single-storey rear extension under permitted development rules. Provided it stays within the size limits (4 metres projection for detached houses, 3 metres for others), doesn’t cover more than half the garden, sits at the rear, and your property isn’t listed or in a conservation area, planning permission is not required.
The PD Rules for Conservatories
Planning law makes no specific mention of “conservatories” — they’re 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.
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
✅ The Larger Home Extension Scheme may give you more room
Under the Larger Home Extension Scheme (prior approval), a single-storey rear extension can project up to 8 metres (detached) or 6 metres (other houses). This includes conservatories. You need to notify the council and allow neighbours to object, but it’s not a full planning application.
Size Limits Explained
| House Type |
Standard PD Limit |
Larger Home Extension Scheme |
| Detached house |
4 metres projection |
Up to 8 metres (prior approval) |
| Semi-detached or terraced |
3 metres projection |
Up to 6 metres (prior approval) |
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)
⚠️ Open-plan conservatories lose the Building Regs exemption
If you knock through between the conservatory and the main house without a proper external-quality door, the conservatory is no longer “separated” and Building Regulations will apply to the whole project — including structural, thermal, and fire safety requirements.
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.
Frequently Asked Questions
Do I need planning permission for a conservatory?
In most cases, no. A conservatory is treated as a single-storey rear extension under permitted development rules. Provided it stays within the size limits (4m projection for a detached house, 3m for semi-detached or terraced), doesn’t cover more than half the garden, is positioned at the rear or side, and your property isn’t listed or in a conservation area, planning permission is not required.
How big can a conservatory be without planning permission?
Under standard permitted development, a conservatory can project 4 metres beyond the rear wall of a detached house, or 3 metres for a semi-detached or terraced house. Under the Larger Home Extension Scheme (which requires notification to the council), these limits increase to 8 metres and 6 metres respectively. The combined footprint of all extensions and outbuildings must also not exceed 50% of the garden.
Do I need Building Regulations for a conservatory?
Not always. Conservatories are exempt from Building Regulations if they are at ground level, under 30m², separated from the house by external-quality walls and doors, have independent or no heating, and at least 75% of the roof and 50% of the walls are glazed. If you open up the conservatory to the main house without a proper door, the exemption no longer applies and Building Regulations will cover the whole project.
Can I build a conservatory in a conservation area without planning permission?
It depends on which PD rights have been removed in your area. In most conservation areas, permitted development rights for extensions still apply — meaning a rear conservatory within the size limits may not need planning permission. However, many conservation areas have Article 4 Directions removing some or all Class A rights. Always check with your local council before starting work in a conservation area.
Want the Full Permitted Development Picture?
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