Do you need
planning permission
for a conservatory?

What the rules actually say

There is no separate "conservatory" class in the planning legislation. A conservatory is treated as an extension under Class A of Part 1 of the GPDO 2015. Every condition that applies to a rear extension applies equally to a conservatory - the depth limits, the height limits, the boundary distances, the 50% curtilage rule. The only exception is that the materials matching condition explicitly excludes conservatories.

This means the same depth limits apply. The same height limits apply. And critically, a conservatory counts toward your permitted development allowance in exactly the same way as any other extension - including when you, or a future owner, want to build something else later.

01Depth limits

Class A, Part 1, Schedule 2, GPDO 2015 — A.1(f)

These are measured from the original rear wall - the house as it was first built, or as it stood on 1 July 1948. Not from any existing extension. If a previous owner built a 2-metre conservatory and you want to replace it with a 3-metre one, only the 3 metres counts - but if you want to add a new extension behind the existing conservatory, you measure the total depth from the original wall.

Through the prior approval route, you can go deeper: up to 8 metres on a detached house or 6 metres on a semi-detached or terrace. This requires notifying your council and a 42-day neighbour consultation process. The fee is £249. For full details, see our extensions guide.

02Height limits

Class A, Part 1, Schedule 2, GPDO 2015 — A.1(c) to A.1(i)

A conservatory cannot exceed 4 metres in overall height, and the eaves and ridge cannot be higher than the existing house. If any part is within 2 metres of a boundary, the eaves are capped at 3 metres. For more on this specific rule, see our eaves height near boundary guide.

03The materials exception

Class A, Part 1, Schedule 2, GPDO 2015 — A.3(a)

This is the one way conservatories differ from other extensions. Class A.3(a) states that exterior materials must be of similar appearance to the existing house - "other than materials used in the construction of a conservatory." This means a UPVC-framed, glass-roofed conservatory on a brick Victorian terrace is permitted development, even though the materials are completely different from the existing house.

The exemption applies specifically to conservatories. If you're building what is effectively a brick and tile extension with some glazing, the standard materials matching rule applies. The distinction matters if the council questions whether your project is genuinely a conservatory or a glazed extension - though in practice this is rarely an issue for a conventionally designed conservatory.

04Other conditions

Class A, Part 1, Schedule 2, GPDO 2015 — A.1(b) to A.1(k)

Everything else that applies to extensions applies to conservatories. The conservatory must be at the rear - not forward of the principal elevation. It counts toward the 50% curtilage coverage limit alongside every other extension, shed, and outbuilding on the plot. It cannot include a balcony, veranda, or raised platform above 300mm.

In conservation areas and other designated land, side conservatories are not permitted development. Two storey conservatories (which do exist, though they're rare) follow the two storey extension rules - maximum 3 metres deep, at least 7 metres from the rear boundary.

05When you need planning permission

Exclusions from permitted development

Flats and maisonettes - permitted development rights don't apply. Listed buildings - you need both planning permission and listed building consent. Houses created through a change of use under Classes G, MA, N, P, PA, or Q of Part 3 - no PD rights. Conservation areas - rear conservatories within depth limits are usually fine, but side conservatories need planning permission. And if any previous extensions have already used the depth or curtilage allowance, you may need to apply.