How much can I extend my house without planning permission?

Our most frequent enquiry comes from homeowners looking to extend without the hassle and time involved in getting planning permission from their local authority. 

Find out how much you can extend by in our helpful guide. 

Whether you’re staying put, or have just moved in to your new pad, plenty of homeowners are asking themselves: how much can I extend my house without planning permission?

Obtaining planning permission can be lengthy and time consuming, so it’s worth knowing what your options are under Permitted Development Rules.

The government is keen to stimulate the building and architecture economy and has extended Permitted Development Rights so that people can extend their homes more easily. 

Extending your house without planning permission: the basics

Under permitted development rules you can build an extension up to six metres  – or eight if your house is detached. There are, however, other conditions.
  • No more than 50% of the land around the house can be covered by other buildings
  • No extensions jutting forward from the front of the house, or from the side in front of an highway.
  • The extension can’t be higher than the top of your roof
  • A single storey extension cannot extend beyond the rear wall of the original building by more than six metres (eight metres if the house is detached).
  • Note: Prior Approval applies to larger extensions, i.e. between four and eight metres on detached houses, three and six metres on other types.
  • The maximum height of a single storey extension is four metres.
  • Double storey extensions more than one storey cannot extend from the rear wall of the house by more than three metres, and cannot come within seven metres of the rear boundary of the plot.
  • No balconies, verandas or raised platforms

Side extensions

Under Permitted Development Rules, a side extension:

  • Cannot measure more than half the existing width of the house
  • Cannot extend more than three metres from the original house
  • Must not front onto a road.

Rear extensions

For single storey rear extensions, Permitted Development Rules allow for:

  • Extend up to eight metres for detached homes, or,
  • Six metres for for all other types of houses. 
Rear extension in Harborne

Do I need planning permission for a side return extension?

Side return extensions are really common in towns and cities, and are generally extend more than three metres from the back of the house, as such, you’ll have to seek prior approval for your side return extension under the Neighbour Consultation Scheme – more on this down below. 

A common result of this is that the side return extension has to respect the height of the boundary wall so that your neighbour doesn’t suffer any loss of light, so sloped rooves are often common with side return extensions.

What about double storey extensions?

Under the new Permitted Development Rules, double storey extensions may extend up to three metres from the original house. In addition, they cannot be within seven metres of the rear boundary of your plot. 

In terms of architecture requirements, the shape of the roof must match the existing home, and the side facing windows must be above 1.7 metres above the floor.

Can my neighbours object to my extension?

Although the new larger home extension scheme is undoubtedly generous, your neighbours do have the right to object to this. If your extension measures over three metres – for terraced/semi-detached houses – or four metres – if it’s detached – then you have to seek Prior Approval under the Neighbour Consultation Scheme.

The council will notify your neighbours, and they have a 21 day period in which they can give valid reasons as to why they believe the extension should not be built. The local authority then has a further 21 days to grant this Prior Approval under the Consultation Scheme, at which point a fee will be payable for a Lawful Development Certificate – which is a great idea anyway – and takes eight weeks to receive a decision. Remember this only applied to the larger extensions over three metres, or four if it’s detached.

Expert extension advice from Lapworth Architects

Depending on whether you’re looking for a side, rear, single or double storey or even a side return extension – size and neighbours are the main consideration when it comes to how much you can extend your house by without planning permission. 

Remember, that Lapworth Architects are experts in this area, and can help you with your design and planning needs. Give us a call, write to us on our live chat, or drop us an email in the form below to start your project and see how we can design you all the space you need!

party wall surveyors

Why Lapworth Architects?

Experienced

Our 20+ years of work mean great design and good relationships with planning departments across the region, giving  our projects the best chance to get planning permission and start building.

Affordable

Your budget is tailored to your needs so you’re always on top of your costs. We’re proud to offer excellent value for money for our services, from design and planning right through to build.

Knowledgeable

Our breadth of knowledge makes us an efficient and sustainable choice of local architect, and we have a vested interest in improving our built environment right here in the West Midlands.

Professional

Wherever you are with your project, if you’re looking for honest, quality advice from professionals, chat to us, leave us a message or call us on the number at the top of the page. Let’s talk!