Conservatory planning permission is one of the most common questions our surveyors are asked, and the honest answer is: usually you don’t need it, but the exceptions catch people out every year. In England, most rear conservatories are built under permitted development, a set of national rules that let you extend without a planning application provided you stay within fixed limits on depth, height, position and garden coverage. Step outside those limits, build on the front of the house, live in a flat, or own a listed building, and a full application is required. This 2026 guide explains the rules as they stand in November 2026, including the building regulations exemption, the Party Wall etc. Act 1996, the planning fees that changed on 1 April 2026, and what to do if you are buying a home with a conservatory that was never approved.
No, in most cases. A conservatory is treated as an extension under Class A of Schedule 2, Part 1 of the General Permitted Development Order 2015, so a single-storey rear conservatory on a house in England is permitted development if it is within 4m of the original rear wall (3m for semi-detached and terraced houses), under 4m high and covers no more than 50% of the garden. Outside those limits you need planning permission.
That is the headline answer, but the word “original” does a lot of work. Permitted development is measured from the house as it was first built, or as it stood on 1 July 1948 if it is older than that. If a previous owner added a kitchen extension in the 1990s, that extension has already used part of your allowance, and a new conservatory beyond it may push you over the limit. The rules are set out in the Town and Country Planning (General Permitted Development) (England) Order 2015 and explained in the Government’s technical guidance for householders, which we also summarise in our permitted development rights 2026 guide.
The table below sets out the limits that apply to a conservatory built under permitted development, together with the prior approval route for larger single-storey rear extensions. Figures are taken from the 2015 Order as amended; the fees are those published by the Planning Portal for applications made from 1 April 2026.
| Rule | Detached house | Semi-detached or terraced | Notes |
|---|---|---|---|
| Maximum rear projection (standard PD) | 4m | 3m | Measured from the original rear wall |
| Maximum rear projection (prior approval) | 8m | 6m | Neighbour consultation; £249 fee from 1 April 2026; not available on Article 2(3) land |
| Maximum height | 4m | 4m | Single storey only |
| Eaves height within 2m of a boundary | 3m | 3m | Eaves must never exceed those of the existing house |
| Garden coverage | 50% | 50% | All extensions and outbuildings combined |
| Side conservatory | Single storey, max half the width of the original house | Same | Not permitted if it faces a highway |
| Front conservatory | Planning permission required | Planning permission required | Cannot extend beyond the principal elevation |
| Householder planning application fee | £548 | £548 | From 1 April 2026 (England) |
If you want a conservatory deeper than the standard limits, the prior approval (or “neighbour consultation”) scheme allows single-storey rear extensions of up to 8m on a detached house and 6m on any other house. You notify the council, which writes to your adjoining neighbours. If nobody objects within 21 days the council must confirm you can proceed; if a neighbour objects, the council decides whether the extension would harm their amenity. The council has 42 days to respond, after which you can begin. The scheme is not available on “Article 2(3) land” – conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites – where the 4m and 3m limits stand.
You will need a full householder application if any of the following apply:
Scotland, Wales and Northern Ireland each have their own permitted development rules, so homeowners outside England should check with their local authority before relying on the figures in this article.
Planning permission and building regulations are two separate systems, and a conservatory can need one without the other. The Planning Portal confirms that a conservatory is exempt from building regulations only when all of the following are true:
The exemption is lost the moment you create a new structural opening into the house or widen an existing one. A conservatory that opens straight into the kitchen with no doors is, for building regulations purposes, an extension, and the whole structure must then meet current standards for structure, insulation and ventilation. Replacing a polycarbonate roof with a solid tiled roof is treated the same way: the new roof must satisfy the regulations for structural safety, thermal performance and ventilation, and most councils expect a building regulations application for the conversion.
If you have inherited a conservatory that was knocked through without approval, a regularisation certificate from the council is the usual remedy, and if the conservatory is also outside planning limits you may need retrospective planning permission.
For planning purposes there is no difference – all three are enlargements of the house and are judged against the same Class A limits. The distinction matters for building regulations. A conservatory is typically defined as having at least 50% of its wall area and 75% of its roof area glazed; an orangery with solid walls and a lantern roof rarely meets that definition and is therefore less likely to qualify for the exemption. If you are weighing up a glazed structure against a solid-roofed extension, our house extension cost guide compares the two.
Often, yes, and this is the step most homeowners miss. The Party Wall etc. Act 1996 applies regardless of whether planning permission is needed. You must serve notice on the adjoining owner if you intend to:
If the neighbour does not consent in writing within 14 days a dispute is deemed to exist and surveyors are appointed to draw up a party wall award. Failing to serve notice does not make the conservatory unlawful under planning law, but it leaves you exposed to an injunction and a damages claim. Our party wall notice guide explains how to draft and serve each notice correctly, and our party wall surveying service can handle the whole process for you.
Permitted development says nothing about what is under the conservatory, but a surveyor will. Conservatories are light structures, and installers sometimes specify shallow strip foundations or a thin slab. On shrinkable clay soils, which cover much of London and the South East, foundations may need to be 1m deep or more, and the presence of a mature tree within influencing distance can push that to 2m or beyond. Drains under the footprint may need diverting under a build-over agreement with the water company. Getting this wrong is the single most common cause of the cracked and dropped conservatories our building surveyors see on pre-purchase inspections.
Three developments are relevant this year:
A conservatory is one of the first things a Level 2 or Level 3 inspection looks at, because it combines three risks: planning, building regulations and structure. A suitably qualified, accredited surveyor – whether regulated by RICS, CIOB, RPSA or another recognised body – will:
Where documents are missing, the usual options are retrospective approval, a regularisation certificate or an indemnity policy. Our building surveying service covers every level of pre-purchase inspection.
Survey Merchant connects homeowners and buyers with a panel of suitably qualified, accredited surveyors regulated by bodies such as RICS, CIOB and RPSA, matched to the specific job rather than assigned at random. For a conservatory project that means a surveyor who can measure your permitted development allowance, advise on foundations and ground conditions, serve and respond to party wall notices and, if you are buying, report on whether an existing conservatory was built lawfully. We cover the whole of the UK and quote transparent fixed fees, and our surveyors turn reports around quickly and offer impartial advice that is not tied to any installer. From the first measurement to the final certificate, you deal with one point of contact.
Ready to start? Book a party wall surveyor for your conservatory, or contact Survey Merchant for a free, no-obligation quote.
Survey Merchant provides access to a panel of accredited and chartered surveyors across 100+ UK locations at fixed fees:
→ Level 2 Home Survey (HomeBuyer Report)
→ Level 3 Building Survey (full structural survey)
→ RICS Red Book property valuations
→ Party wall surveyors — notices, awards & schedules of condition
→ Expert witness surveyors — CPR Part 35 reports for property disputes
