Roof extensions

Planning permission may not be required providing:

The Enlargement of a dwelling house consisting of an addition or alteration to its roof.

In order for a development to be PD the development must comply with the following:

• 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.
• Roof extensions not to be permitted development in designated areas*.

If a development is considered to be PD under class B the following conditions must be applied:

•  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, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the eaves.

Any other alterations to the roof of a dwelling house

• In order for a development to be PD the development must comply with the following:
• Any alteration to project no more than 150 millimetres from the existing roof plane.
• No alteration to be higher than the highest part of the roof.
• Side facing windows to be obscure-glazed; any opening to be 1.7m above the floor.

Porches

Planning permission may not be required providing:

• The ground floor area (measured externally) would not exceed three square metres.
• Any part would not 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 dwelling house and the highway.

Note: This is unchanged from previous GPDO