Planning Guidance

Will my house extension require planning permission?
It seems a straight forward enough question and it is probably the single most common question put before us – “will my house extension require planning permission?” There are many pitfalls to be avoided avoid along the way but if your proposed house extension satisfies the criteria below then the chances are you will not need to go down the full plans route. Please note that in most cases you will still need to satisfy building regulations when building a new extension or carrying out other such works to your property.

Building regulation approval can be achieved either via pre-site approval whereby detailed plans of your proposed works are submitted to your local building control department or via onsite approval method whereby you issue a building order to your building control department at the start of the works and then your approval is achieved via regular onsite visits by your local council building control officer.With both methods there will be a requirement for the building officer to attend the site at several key stages during the works and provided he or she is happy with everything they will grant your new extension with building regulatory approval. Of course, being an architectural services company you would expect us to advise you to obtain a full set of building Regulation drawings and go down the pre site approval route every single time.

This is not the case however, and for a straightforward extension, and provided you have 100% faith in your building contractors ability then onsite approval by way of a building notice may well be the better option for you – it certainly reduces time as pre-site building regulation approval for an average house extension will take around 5 weeks to obtain not to mention the plan checking fees. Even when working to a building notice it is still beneficial to have a set of building regulations plans so that the builder can demonstrate the intended build to the building control officer during his inspection, it also helps the builder to construct a far more accurate price for the building of your house extension.

If your house extension plans have just passed planning and you have not yet employed a builder then it is highly recommended to have a full set of building regulation drawings produced as these will be used as builders work drawings by whichever builder you apoint to carry out the works. Furthermore, provided the builder provides a quotation based on your plans there is less chance of any misunderstandings which may result in you incurring additional charges for your dream house extension to the price originally agreed with your builder. The other advantage of obtaining building regulation plans is that provided your apointed builder carries out his works to the specification on the plans then your extension should pass building regulations control with ease.

If your proposed house extension meets the criteria for permitted development rights but you want complete peace of mind then you can obtain something called a lawful development certificate from your local authority. For this you will need to send in plans for approval but the local authority fees are less than a full plans application.

Planning Permission For House Extensions?
An extension or addition to your home will be considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

  • More than half the area of land around the “original house”* would be covered by additions or other buildings.
  • No extension forward of the principal elevation or side elevation fronting a highway.
  • No extension to be higher than the highest part of the roof.
  • Maximum depth of a single-storey rear extension of three metres for an attached house and four metres for a detached house.
  • Maximum height of a single-storey rear extension of four metres.
  • Maximum depth of a rear extension of more than one storey of three metres including ground floor.
  • Maximum eaves height of an extension within two metres of the boundary of three metres.
  • Maximum eaves and ridge height of extension no higher than existing house.
  • Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house
  • Two-storey extensions no closer than seven metres to rear boundary.
  • Roof pitch of extensions higher than one storey to match existing house.
  • Materials to be similar in appearance to the existing house.
  • No verandas, balconies or raised platforms.
  • Upper-floor, side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor.
  • On designated land* no permitted development for rear extensions of more than one storey.
  • On designated* land no cladding of the exterior.
  • On designated* land no side extensions.

* The term “original house” means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

* Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Planning Permission For Porches?
The planning rules for porches are applicable to any external door to the dwelling house. You need to apply for planning permission when:

  • The ground floor area (measured externally) would exceed three square metres.
  • Any part would be more than three metres above ground level (height needs to be measured in the same way as for a house extension)
  • Any part of the porch would be within two metres of any boundary of the dwellinghouse and the highway.

Planning Permission For Outbuildings?
Rules governing outbuildings apply to sheds, greenhouses and garages as well as other ancillary garden buildings such as swimming pools, ponds, sauna cabins, kennels, enclosures (including tennis courts) and many other kinds of structure for a purpose incidental to the enjoyment of the dwelling house.

Outbuildings will be considered to be permitted development, not needing planning permission, subject to the following limits and conditions:

  • No outbuilding forward of the principal elevation fronting a highway.
  • Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.
  • Maximum height 2.5 metres within two metres of a boundary.
  • No verandas, balconies or raised platforms.
  • No more than half the area of land around the “original house”* would be covered by additions or other buildings.
  • In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from house to be limited to 10 square metres.
  • On designated land* buildings, enclosures, containers and pools at the side of properties will require planning permission.
  • Within the curtilage of listed buildings any outbuilding will require planning permission.

*The term “original house” means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

*Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Planning Permission For Loft Conversions?
A loft conversion for your home will be considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

  • A volume allowance of 40 cubic metres for terraced houses.
  • A volume allowance of 50 cubic metres for detached and semi-detached houses.
  • No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway.
  • No extension to be higher than the highest part of the roof.
  • Materials to be similar in appearance to the existing house.
  • No verandas, balconies or raised platforms.
  • Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor.
  • Roof extensions not to be permitted development in designated areas*.
  • Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the eaves.

*Designated areas include national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Planning Permission For Loft Conservatories
Adding a conservatory to your home will be considered to be permitted development, not needing an application for planning permission, subject to the following limits and conditions:

  • More than half the area of land around the “original house”* would be covered by additions or other buildings.
  • No extension forward of the principal elevation or side elevation fronting a highway.
  • No extension to be higher than the highest part of the roof.
  • Maximum depth of a single-storey rear extension of three metres for an attached house and four metres for a detached house.

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