Did you know you often don’t need planning permission to build on to your existing property? The rules are called ‘permitted development rights(PD)’ which allow you to add certain spaces to your house without needing to apply for planning permission.

Moons ago, my little one caught me in front of a screen while I was working on a new build project, ‘mummy, why can’t houses grow like plants?’ he asked. ‘They can…’ I responded. 

Organic Architecture is not a new concept: it was coined by Frank Lloyd Wright in the last century. The movement is a reference to design and build buildings in a way that reflects and mimics nature.  My favourite examples are Fallingwater house by Wright and The Friendly Alien in Graz, Austria.  

I imagine a happier journey from cradle to grave and rebirth with our cities, towns, schools, theatres and shops all being part of the living organism. Like a tree or plant, a home could grow naturally in sync with its occupants’ life span, could record a family’s history and not only adapt to their needs but could also echo and reflect their identity and aspirations… 

Stop…  enough daydreaming: let’s get down to earth and talk about the rights (permitted development) that enable you to enlarge your house without applying for planning permission. 

Hope this simplified guide sheds some light on a journey of growing and updating your home. 

Build area (site coverage): 50%

The maximum area of any extensions to the original house* would be 50% of the total area of land around the house which is also known as curtilage of house. 

*Original house: As it was when it was first built, or as it was on 1 July 1948 (if it was built before that date).

This 50% limit excludes the existing and proposed outbuildings as well as any existing or proposed new extensions to a house. You must also take account of a detached garage and garden shed.  

The illustration above shows: the extension area edged in orange should not be     
bigger than 50% of curtilage area coloured in green. 

Height:  keep aligned with existing house  

As an additional part to the original house, extensions can be no higher than the apex of the existing roof and the proposed eaves should not be higher than existing eaves.  

If your build an extension within 2 metres of a boundary (let us say to your garden wall) then the height of the eaves need to be lower than 3 metres. 

Location: not in an eye-catching position  

Any extension on the front or side of your house that will be closer than the original house to a public highway will need planning permission.

A highway can be a road or a footpath. It does not have to be a drivable route.

It is common law that says A highway is a way over which there exists a public right of passage, that is to say a right for all Her Majestys subjects at all seasons of the year freely and at their will to pass and repass without let or hindrance. (Halsburys Laws 21[1]).

Materials: try to match 

Materials used in any exterior work must be the same or similar to the appearance of the existing house.

Your extension works cannot  include:

  • verandas, balconies or raised platforms.
  • a microwave antenna (e.g., TV aerial or satellite dish).
  • a chimney, flue or soil vent pipe.
  • any alteration to the roof of the existing house.
  • On Article 2(3) designated land* the work must not include cladding of the exterior.

*Article 2(3) designated land means:

  • a conservation area
  • an area of outstanding natural beauty
  • an area specified by the Secretary of State for the purposes of enhancement and protection  of the natural beauty and amenity of the countryside
  • the Broads
  • a National Park
  • a World Heritage Site

Typology: rear extensions (single storey)

If you have a detached house, under the permitted development you can build your rear extension up to four metres from the rear wall of your original house. For any other house (a semi or terraced house), it is up to three meters. 

The illustration above shows: the size of a rear extension does not 
exceed 50% of the curtilage of the original detached house, 
the maximum length of a one-story rear extension is four meters.

The illustration above shows: the size of a rear extension is less than 50% of the curtilage of the original semi-detached house, the maximum 
length of a signal-story rear extension is three meters. 

Prior approval for bigger extensions

Prior approval process applies: 

If the original house is not located on Article 2(3) designated land and you are planning a larger single-storey rear extension, which is defined as exceeding over four and up to eight metres beyond the rear wall of the original house; is detached and over three and up to six metres from other houses. 

This requires that the relevant Local Planning Authority is informed of the proposed work via a prior approval application

Typology: side extensions (single story) 

No planning permission is needed  if you are going to build a single storey side extension no higher than four metres. Additionally, if is only up to half the width of the original house and will be within two metres of a boundary (e.g. your garden wall) then the height of the eaves need to be lower than three metres. 

Note: Where on Designated land: all side extensions will require householder planning permission. 

You may build a 2-storey extension within the limit of PD if the extension is within three metres from the rear wall of the original house. Additionally it must be a minimum of seven metres away from any boundary of its curtilage which is opposite the rear wall of the original house.    

The extension must have a roof pitch that matches the existing house (this also applies to any upper story built on an existing extension).

Windows that are located upper-floor in a ‘side elevation’ must be obscure-glazed; and non-opening unless the openable part is more than 1.7 meters above the floor. 

Planning permission will be required if you are planning a side extension with more than one storey. 

If you would like to grow your house and unlock your property’s potential, we would be delighted to hear from you –  let’s talk about your ideas… 

Call us on:  01254 619706 

or get in touch simply by filling out the form below (your data is safe with us).

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