What are the laws on House Extensions?

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Extending a house space is a great way to add extra comfort and value to the property without moving, though it can be daunting when you first start looking into it. However, when it comes to an extension, there are quite a few rules, you have to follow, but this should not put you off.

House extension London can submit and manage any planning approvals, regulations or any kind of agreement approval work on your behalf, so you don't have to worry about anything. However, we are listing here a few important and necessary rules, which you may require for your house extension work.

Planning Permission -

If any changes you are making within the rules of permitted development, you may not require Planning permission approval. If it's not coming under the permitted development, then you can apply for planning permission through planningportal.co.uk or your local authority.

Permitted Development -

Permitted development permits you to do minor changes to your house without any planning permission, as long as your home is quite original and unmodified. You don't need to notify anyone.

If you are trying to get an extension that falls outside of the below parameters, you need to seek Full Planning Permission. Though you can increase your double-storey rear extension by using the following criteria:

  • Post extension, do not develop more than 50% of your back garden
  • The external cladding and roof inclination should match with the existing property
  • A few other factors include:
    • The closeness to the side boundary
    • The distance from your rear boundary


However, there are a few reasons House extension London has listed here, why you still need to submit an application though you don't need approval.

What permitted development covers?

  • Extensions or other builds can cover not more than half of the area of land around the original house. This involves shelters and other outbuildings too.
  • The extension should be at the rear of the property, and if the extension includes building out towards the main road, then you may require planning permission.
  • No extension should be ahead of the principal eminence or side elevation facing a highway.
  • Single storey rear extensions can be increased up to three meters ahead from the original rear of the house if it's a terraced or semi-detached property or four metres or if it's a separated property.
  • Materials must be kept with your current property's appearance unless you're building a conservatory.
  • Single storey rear extensions should not exceed the four meters height.
  • Single storey rear extensions should not go beyond the rear wall of the original house by more than three metres if it is an attached apartment, or maximum by four metres if detached. If you want a more significant extension, you should have a look at the neighbour consultation scheme.

Rules for Multiple Storey / Two-storey extension -

  • In more than one storey extension, the extension cannot extend beyond the rear wall of the original house by more than three metres. Applicable for attached and detached properties as well.
  • The maximum height of the extension's eaves could be 3 meters if it is within 2 metres of a boundary.
  • Eaves and elevation height of expansion can't get higher than the existing house.
  • Roof pitch must match the current home, or should be as close as possible.
  • Two-storey extensions must be minimum seven metres away of the rear boundary.
  • No galleries, balconies or raised platforms extension can be done without planning permission.
  • On designated land, two-storey extensions do not get covered by permitted development rights.
  • Side elevation upper-floor windows that are in a wall or roof slope need to be obscure-glazed and should not open unless the open parts are more than 1.7 metres above the floor of the room in which it has been installed.
  • The extensions exterior must use similar materials in appearance to those of the existing house.

Rules for Side Extension -

  • Single storey, side extensions cannot exceed a four metres height and mustn't have a width of more than half of the actual home.
  • No side extensions are permitted, for the designated land.

Rules for Loft Conversion -

As long as the loft conversion complies with the few parameters, it can be achieved under permitted development. Thought it needs to follow below limits and conditions:

  • For the terraced houses, a volume allowance is 40 cubic metres additional roof space.
  • The extension should not cross the distance of the existing roof slope of the principal eminence that fronts the highway.
  • 50 cubic metre extra roof space, volume allowance is approved for detached and semi-detached houses.
  • Materials should be comparable in appearance to the actual home.
  • The extension should not go higher than the highest part of the roof.
  • The roof expansion cannot overhang the exterior face of the wall of the original house.

Rules for Rear Extension -

Where you re looking for an extension beyond the side elevation of the original house, you need to follow below extension rules:

  • The extension cannot exceed beyond four metres in height.
  • The rear extension can only be done in a single storey.
  • It should only be up-to half the width of the original house.

House extension London is determined to help you to achieve your goals and increase the quality of your life. Reach out to us today to get started on your project.




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