Dormers: Planning Permission Guide

Dormers are considered to be permitted development. Therefore, seeking planning permission from the local authority is not required, subject to compliance with PD rights.

What Does the Legislation Say?

Class B of The Town and Country Planning (General Permitted Development) (England) Order 2015 permits the addition or alteration to a roof of a house, subject to limitations and conditions.

Key Limitations

Some of the limitations are:

• The dormer must not exceed the highest part of the roof of the house
• The dormer cannot be erected on the front of the house
• The cubic content of the roof space must not exceed 40 cubic metres for a terrace house, and 50 cubic metres for any other house

The cubic content of the roof space must not exceed 40 cubic metres for a terrace house, and 50 cubic metres for any other house.

Important Conditions

Some of the conditions are:

• The materials used in the exterior work must be similar to the existing house
• The dormer must be set back from the eaves by 0.2 metres
• Any window on a side elevation must be obscured and non-opening below 1.7 metres of the floor of the room