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Do I need planning permission for an extension?

Whether it is the costs associated with moving, potential interest rate changes, or a growing family, many people will see staying put and adapting their home as the most viable option.

If you are considering building work you will probably be doing your research into the type of extension you wish to make. 

Our series of buying guides aims to give you as much information around our industry and products before you get a quote. So let’s begin with the basics…

The type of development

Your building project will likely fall into one of these areas…

> Extension

> Orangeries

> Conversatories

> Full scale redevelopment

We previously published a guide on ‘planning permission for a conservatory’ and many aspects of this article will overlap, particularly around single story projects.

What is planning permission?

Planning permission involves the homeowner requesting from their local planning authorities whether they can carry out certain building work to their home. The outcome will either be granted (possibly subject to certain conditions) or refused. If you have any queries about a particular case, the first thing to do is to contact your local planning authority.

Planning permission for extensions explained...

Planning encompasses (a) building on, (b) modifying, or (c) changing the use of land or buildings on that land. The large majority of residential extensions will only touch on points a & b.

Planning permission aims to provide a consistent set of considerations around the visual effects of construction work on the existing property, but also the properties in the surrounding area. Certain types of structures are permitted without planning permissions and this is due to ‘Permitted Development Rights’ that are handed down from Parliament.

In short, a single extension can be constructed without planning permission if the following criteria are met…

  • > The extensions maximum roof height does not exceed 4 metre, this falls to 3 metres if the development falls within 2 metre of your boundary.
    • > The extension does not cover more than half of your garden (garden not total plot area)
    • > The maximum height of the extension roof ridge is not higher than the eaves of the existing roof.
    • > If you’re planning a side extension extension this cannot extend beyond half the width of the property.

When do I need planning permission for an extension?

Extensions and other single story constructions like conservatories can be exempt from planning permission providing that they abide by the following conditions…

  • > The extension does not cover more than half of your garden (garden not total plot area)
  • > An extensions greater than one storey must not extend beyond the rear wall of the original house footprint by more than 3m or be within 7m of any boundary opposite the rear wall of the house.
  • > The maximum height of the extension roof ridge is not higher than the eaves of the existing roof.
  • > The maximum height is under 4 metres, this reduces to 3 metres if the extension falls within 2m of your properties boundary line.
  • > A single-storey rear extension cannot extend beyond the rear wall of the original house by more than 4m if a detached house or 3m if an attached house.
  • > Until recently (30 May 2019 to be precise), this 3m – 4m limit was increased to 6m for an attached house and 8m for a detached house subject to the Neighbour Consultation Scheme*
  • > No conversatory is further forward than the principal elevation (front of house) or side elevation (side of house) which fronts a highway.
  • > No part of the extension is higher than the highest part of the original properties roof.
  • > The roof pitch of an extension higher than one storey is required to match the existing house roof pitch – this is unlikely to affect extensions as they are almost always single storey.
  • > Extensions to the side of a property are not permitted to extend beyond half the width of the house.

*Providing the property was outside Article 1(5) designated land and sites of special scientific interest.

No doubt you will find yourself referencing the points above vs. your intended building site. Once you have established whether you will need planning permission the next step to consider is building regulations.

What are building regulations?

Often referred to a building regs or build control, Building regulations are a governmental set of standards covering the health and safety of a building. Complying with building regulations is separate to that of planning permission. Building regulations can either be through a private company or via your local council – the cost should not differ to any great extent.

Building regulations for extensions explained

Some extensions in England and Wales will be exempt from building regulations under the following conditions…

  • > The extension is being built at ground level
  • > The floor space is under 30 msq
  • > 80% or more of the extension is translucent.
  • > The heating for the new extension is independent (ie not feeding off your boiler or central heating system)
  • > Your extension is over 1m+ away from any boundary wall / fence / perimeter.
  • > The extension is separated from the existing structure by an external wall, window or doors.

Do I need building regs for an extension?

If you were planning on an open plan extension (ie removing a doorway or wall between your house and the extension), you will need to apply for building regulations approval. Part of this requirement will also require you to demonstrate that the extension is as heat efficient as the rest of the house. 

This open plan approach will require the submittal of structural drawings and heat-loss calculations to your local authority, where they will assess and either grant or reject your approval.

Other Considerations with planning an extension

Water Board Approval

If your extension is to be built within 3 metre of a public sewer (main drains), you will require permission from your regional water board authority. Upon completion your local building control officer (aka building regs) will want to inspect the work to check for correct installation and possible damage to the sewer – so remember do not fill your drainage channels until he / she has inspected the work.

 

Party wall approval

If your planning building work requires excavation around or near a neighbouring property you must notify your neighbour in writing at least 2 months prior to any building work. This will typically concern projects where you are digging foundations within your garden – especially if you live in a traditional semi-detached or terraced house. 

Restrictive Covenants

Restrictive covenant are designed to impose restrictions on the use of land so that the value and ensure enjoyment of adjoining land will be preserved. This does not necessarily mean you cannot build a conservatory, providing the design is sympathetic to the surrounding property. For more information please visit the HomeOwners Alliance website.

 

Listed Buildings & Conservation Areas

Properties within conservation areas or buildings that are listed must comply with set rules that govern the work that can be carried out on a buildings exterior – for listed building this can also apply to the interior. Any alterations, like a new conservatory, must be in-keeping with the style of the property.

 

How to apply for planning permission for your extension?

If your planning extension falls outside planning permission and building regulation exemptions then you will need to contact your local planning authority.

This will determine the viability of your proposed build. Providing this is approved you can then start planning your build. Build control (building regs) should be booked prior to construction starting, however more importantly is that they inspect (usually in person) the building site during key times of the build (eg: drainage installation, foundation digging or steel installation). 

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