First Floor & Two Storey Extensions - Home Extensions - Improve your home

First Floor and Two Storey Extensions

Benefits

Increases your living space, creating the opportunity to add an additional bedroom or bathroom etc.
Adds value to the property
Avoid the time, effort and costs associated with moving home

N.B. A two storey extension is not a great deal more expensive than a single storey extension as both need foundations and a roof.

Key Points

Site Coverage: Did you know that you will need planning permission if the proposed two storey or first floor extension (when taken with existing extensions, outbuildings and decking for example), will cover more than 50% of the land around your home?
Location: In terms of location, if your property fronts or sides a road and you wish to put an extension closer to that road then you will need planning permission. In addition, if you propose to site a 2 storey extension within 7 metres of a rear boundary, you will require planning permission.
Height: The extension can be no higher than the highest part of the existing roof and if you are building within 2 metres of a boundary, the maximum eaves height can be no more than 3 metres. This last point will apply more to single storey as opposed to two or indeed first floor extensions.
Depth: The maximum depth of any first or two storey extension is 3 metres.
Veranda: You will require planning permission if you wish to add a veranda, balcony or raised platform to the structure.
Roof Pitch and Materials: At first floor level, the roof pitch must match that of the existing house or else you will require planning permission. Similarly, you will have to use materials of a similar appearance. Again, what is considered a similar material is unclear and will be the subject of further consideration at some future point on this site.
Windows: If you wish to add a side facing window to your first of two storey extension, it will have to be obscurely glazed and any opening part has to be located 1.7 metres above floor level.
Cladding: Last but not least, if your house occupies designated land, you cannot clad it. What this means is not entirely clear but we will attempt to interpret this in future articles.

Two Storey Extensions

Do I Need Planning Permission?

Planning Permission may not be required subject to the following limits and conditions:-

No 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 3 metres for an attached house and 4 metres for a detached house.
Maximum height of a single storey rear extension of 4 metres.
Maximum depth of a rear extension of more than 1 storey of 3 metres including ground floor.
Maximum eaves height of an extension within 2 metres of a boundary of 3 metres.
Side extensions to be single storey with maximum height of 4 metres and width no more than half that of the original house.
2 storey extensions no closer than 7 metres to the rear boundary.
Roof pitch of extensions higher than 1 storey to match existing house.
Materials to be similar in appearance to existing house.
No verandas, balconies or raised platforms.
Upper-floor, side facing windows to be obscure glazed; any opening to be 1.7 metres above the floor.
On designated land* no permitted development for rear extensions of more than 1 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.