Double storey extensions planning facts

Adding an extension to your home can significantly increase the value of it due to the amount of living space it adds to the property. An extension is also a viable option to moving and will give property owner the vital extra space they need, but in the past gaining planning permission was often difficult for homeowners.

However, in 2012 the Government announced plans to soften the guidelines for home extensions; these new guidelines came into force in 2013.

The new planning guidelines relaxed the rules for permitted developments, and provided the changes that are planned to your property fall within these guidelines, the property owner won’t always need planning permission.

Double storey extensions planning facts/guidelines

Detailed below are some of the most recent planning guidelines for double storey extensions.

  • Permitted development only applies to the “original house”. According to government guidelines, this means: a “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.
  • Under government guidelines, two-storey extensions are limited to 3 m long from the rear wall, however, the government states a rear extension must be “no closer than seven metres to the rear boundary” The three metre rule applies to the detached, semi-detached and terraced homes.
  • Side facing Windows on an upper floor must be fitted with obscure glazing. If some parts of the windows do open, they must be at least 1.7 m or more from the floor
  • The roof pitch must be identical to the existing property.
  • If a double story extension is to include a balcony or Veranda or rear platforms this would not be considered a permitted development and you will need planning permission.
  • For a double story extension to be considered a permitted development the eaves and the ridge height cannot extend beyond the height of original house.
  • The extension mustn’t extend beyond 50% of the original house. Existing outbuildings are included in the 50%
  • The materials used must be similar to those in the original house for it to be considered a permitted development. This includes all of the materials used on the exterior of the extension.
  • Guidelines further state that the eaves of the new property cannot be more than 3 m if you plan to build the extension “within 2 m of a boundary”.

Designated Land

The rules for designated land such as conservation areas and Areas of Outstanding Natural Beauty are much stricter

On designated land, a double story extension would not be considered a permitted development and planning permission would be required.

Building regulations

Although planning permission won’t necessarily be required for your extension, the changes you intend to make to your property will need to be approved by Building Control.

Obtaining advice

Although there has been some softening of the rules, which will remain in force for the near future, the guidelines are still complex; before moving ahead with your plans for an extension it is advisable to seek advice from a construction firm.

In addition, you’ll also want to speak to your local council over plans for a two storey extension just to clarify that your planned extension won’t need permission.