Do You Need Planning Permission to Add Storeys?

Thinking about adding extra levels to your home? You might find that increasing the number of storeys counts as 'permitted development', which means you can proceed without submitting a full planning application. However, this isn't a free pass; you'll need to adhere to certain limits and conditions, and your local council must grant its 'prior approval' before you start any work.

If your proposed project doesn't fit within these specific guidelines for permitted development, then you'll definitely need to submit either a Householder or a Full Planning Permission application.

Is Your House Eligible for an Upward Extension?

To qualify for permitted development, allowing you to build upwards, your current home must satisfy these fundamental criteria:

• Your property must be a single house, not a building containing multiple flats or a flat itself within such a structure.

• Construction of your house must have occurred specifically between 1 July 1948 and 28 October 2018.

• You cannot have previously added any extra storeys to the property.

• Your home must not be situated in an Article 2(3) designated area (which includes places like conservation areas, National Parks, or World Heritage Sites – see full definition below) or a Site of Special Scientific Interest.

• The house must not have been converted into a residential dwelling from a non-residential building using permitted development rights in the past.

Rules for Your New Storeys

Beyond your house's eligibility, the proposed additional storeys themselves must also comply with these specific regulations:

• How Many Storeys Can You Add?

  • If you own a single-storey home, you are permitted to add one additional level.

  • For houses that already have more than one storey, you can extend upwards by two new levels.

• Height Restrictions:

  • The overall height of your entire house, once complete, cannot exceed 18 metres.

  • Each new storey you build must not cause the overall height to increase by more than 3.5 metres.

  • If your property is attached to other buildings (for example, a terraced or semi-detached house), its final total height must not be more than 3.5 metres taller than the highest attached, adjoining, or row-aligned building next to it.

• You must build the extra storeys on the 'principal part' of your house (this means the main section, excluding any lower extensions at the front, side, or rear).

• The new storeys cannot be taller than 3 metres, or taller than any existing storey within the principal part of your house (measured from inside, floor to ceiling), whichever measurement is smaller.

• You can only carry out engineering work to strengthen the existing walls and foundations, and this work must stay within your current garden area (known as the curtilage).

• The external materials you use for the new storeys must closely match the appearance of your house's existing exterior.

• You are not allowed to install windows on any wall or roof slope that forms a side elevation of the property.

What Happens After Construction?

Once you've finished building your new storeys, you must ensure these conditions are maintained:

• Your property must continue its use as a private residential home.

• You must remove any temporary or permanent support structures so that nothing visible remains on or attached to your home's exterior.

• The angle of the roof on the 'principal part' of your house must stay exactly as it was before you started the upward extension project.

Important Terms Explained

Principal part:

This describes the central or main body of your house. It specifically excludes any extensions that might be at the front, side, or rear of your property if they are of a lower height, irrespective of whether they were part of the initial construction or added at a later date.

Article 2(3) designated land:

This classification applies to areas that have specific environmental or historical protections. It encompasses land found within:

• A conservation area.

• An Area of Outstanding Natural Beauty.

• Any area officially designated by the Secretary of State for improving and safeguarding the natural beauty and pleasant character of the countryside.

• The Broads.

• A National Park.

• A World Heritage Site.