Do I Need Planning Permission for an Extension? A Council by Council Guide for Essex

Many extensions can go ahead under permitted development, but plenty cannot. Here are the national rules, the routes available and which Essex council deals with your address.

Many single-storey extensions, and some two-storey ones, can be built in England without a planning application under national rules called permitted development. If your house still has its permitted development rights, is not in a conservation area or other protected land, and the extension stays within set limits on depth, height, width and materials, you usually do not need planning permission for an extension.

If any one of those conditions is not met, you need a householder planning application to your local council, which councils aim to decide within 8 weeks. Below we set out the national limits, the routes open to you and which Essex council deals with your address.

How permitted development works for extensions

The rules sit in Class A of Part 1 of the Town and Country Planning (General Permitted Development) (England) Order 2015, usually shortened to the GPDO. They apply to houses, not flats, and every measurement is taken against the "original house". That means the house as it was first built, or as it stood on 1 July 1948 if it is older. Any extension added by a previous owner counts against your allowance, and that catches a lot of people out.

The limits are the same in Chelmsford as in Harlow. What changes is whether a particular property still has its rights.

The main permitted development limits

Single-storey rear extensions

• No deeper than 4 metres beyond the original rear wall on a detached house, or 3 metres on a semi-detached or terraced house.
• No higher than 4 metres.
• Within 2 metres of a boundary, the eaves can be no higher than 3 metres.
• The eaves and ridge can be no higher than those of the existing house.

The larger home extension route

Outside conservation areas and other protected land, a single-storey rear extension can go deeper: up to 8 metres on a detached house and 6 metres on a semi or terrace, still no higher than 4 metres. This is not automatic. You must first notify the council under the prior approval process. The council writes to the adjoining neighbours, and if anyone objects it weighs up the effect on their amenity, mainly light and outlook. The council has 42 days to decide, and you must not start until you have approval or the 42 days have passed without a decision.

Side extensions

A side extension under permitted development must be single storey, no higher than 4 metres and no wider than half the width of the original house. No extension can sit forward of the principal elevation (normally the front of the house), or forward of a side wall that faces a road.

Two-storey rear extensions

• No deeper than 3 metres beyond the original rear wall.
• At least 7 metres from the rear boundary.
• The roof pitch should match the existing house as far as practicable.
• Upper floor windows in a side wall must be obscure glazed and fixed shut, unless the opening part is more than 1.7 metres above the floor.

Rules that apply to every extension

• Materials must be similar in appearance to the existing house (conservatories are the exception).
• Extensions and other buildings, not counting the original house, must not cover more than half of the land around the original house, known as the curtilage.
• No verandas, balconies or raised platforms more than 300 millimetres high.

These are the headline limits. The government's technical guidance on the Planning Portal covers the detail, and a good designer will check each one against your house.

When permitted development rights do not apply

• Flats and maisonettes. Householder permitted development rights for extensions apply to houses only, so any extension to a flat or maisonette needs planning permission.
• Article 2(3) land. This covers conservation areas, National Parks, National Landscapes (formerly Areas of Outstanding Natural Beauty), the Broads and World Heritage Sites. Here side extensions, two-storey rear extensions, exterior cladding and the larger home extension route are all ruled out, although a modest single-storey rear extension within the standard limits may still be possible.
• Article 4 directions. A council can remove some permitted development rights across a defined area, often to protect the character of a street.
• Planning conditions. On newer estates the original planning permission sometimes removed permitted development rights by condition, so it is worth checking the planning history of your house.
• Listed buildings. An extension to a listed building needs listed building consent, which is separate from planning permission. Carrying out work without it is a criminal offence.

Your council's online planning search shows the history of your property and any conditions attached to past permissions. Its website will also show conservation area boundaries and any Article 4 directions.

Lawful Development Certificates

A Lawful Development Certificate (LDC) is a formal confirmation from the council that a proposed extension is lawful, in other words that it falls within permitted development. It is not compulsory, but we recommend one for most permitted development extensions, for three reasons:

• You get certainty before you spend money on structural calculations and a build.
• Buyers' solicitors often ask for proof that an extension was lawful when you come to sell.
• It settles the question if a neighbour later complains to the council.

You apply with drawings showing the existing house and the proposal, and councils generally aim to decide within about 8 weeks.

Householder planning applications

If your extension does not fit within permitted development, you submit a householder application. A typical submission includes the application form, a site location plan, a block plan, existing and proposed floor plans and elevations, and sometimes a design and access statement or a heritage statement. Once the council has validated it, neighbours are consulted by letter or site notice, and the planning officer assesses the scheme against the local plan and national policy.

The target for a householder decision is 8 weeks from validation. If permission is refused, you can amend and resubmit, or appeal to the Planning Inspectorate, which for householder appeals must be lodged within 12 weeks of the decision.

Who is your council? Essex planning authorities

Essex is not one planning authority. Essex County Council deals with matters such as highways, minerals and waste, but householder applications go to your city, borough or district council, or to Southend-on-Sea or Thurrock, which are unitary councils.

• Chelmsford: Chelmsford City Council
• Colchester: Colchester City Council
• Basildon, Billericay and Wickford: Basildon Council
• Brentwood: Brentwood Borough Council
• Braintree and Witham: Braintree District Council
• Harlow: Harlow Council
• Southend-on-Sea and Leigh-on-Sea: Southend-on-Sea City Council
• Grays: Thurrock Council
• Canvey Island and Benfleet: Castle Point Borough Council
• Rayleigh: Rochford District Council
• Maldon: Maldon District Council
• Epping and Loughton: Epping Forest District Council
• Saffron Walden: Uttlesford District Council
• Clacton-on-Sea: Tendring District Council

Each council runs its own online planning search (handy for seeing what has been approved on your street). Most offer pre-application advice, where an officer gives an informal view on a scheme before you apply. Local plans and design guidance differ between councils, so do not assume that something approved in one district will be approved in the next. If you live near a boundary and are not sure which council is yours, look at your council tax bill: the council that sends it is your local planning authority.

What we see on extensions across Essex

On the newer estates around Chelmsford, Braintree and Colchester, the first thing we check is the original estate permission, because a condition removing permitted development rights turns a simple project into a planning application. If you are weighing up house extensions in Chelmsford or house extensions in Colchester, that check takes minutes on the council's planning search.

Southend-on-Sea has a lot of Victorian and Edwardian terraces, where the 3 metre rear limit and the narrow side return shape most designs, and where the prior approval route can add useful depth. You can see the kind of work we take on there on our page about house extensions in Southend-on-Sea. In Basildon, Brentwood, Harlow and building work in Grays, many of the semi-detached and terraced houses suit a 6 metre single-storey rear extension under prior approval, provided the neighbours' light is not unduly affected.

Planning is only half the picture

Permitted development or planning permission tells you whether you can build. It does not cover how the extension is built. Building regulations approval is needed for almost every extension whether or not planning is required, and if you are building on or near a boundary you may need to serve notice on your neighbours under the Party Wall etc. Act 1996. We will cover both in more detail in later posts, and our house extensions service page explains how we work with your designer and building control from start to finish.

In short: check whether your house still has permitted development rights, measure the proposal against the national limits, get a Lawful Development Certificate if it fits, and talk to your council early if it does not.