There is no single legal definition of "habitable room", as its use and meaning are subject to context. Generally, a habitable room is a space in a building that is designed for people to live, sleep, or spend extended periods of time in, but does not include bath or toilet facilities, corridors or utility rooms.

To qualify as permitted development some household building work projects – notably extending a house – must not exceed limits to the volume being added.  

In England, the volume allowance mostly applies to loft conversions. You can read more on the Planning Portal. 

Use the volume calculator to find out the volume of several loft conversion and extension types.

The addition of a new external doorway will often fall under permitted development rights, meaning an application for planning permission is not required. This applies where the new doors are of similar appearance to those used elsewhere on the original building.

Permission may be required if your property is listed, you live in a conservation area oran Article 4 direction is in place. In these circumstances it is best to contact your local planning authority for more advice.

New external doorways which create a new or widened opening must comply with building regulations. A new structural opening will require a building regulations application.

The installation of a new door can be completed by a 'competent person' to ensure building regulation requirements are met. For more information on the competent person scheme and to find a registered person, visit the GOV.uk website.

Changing a standard garage door to an electric garage door will not normally require planning permission. Instead, they are covered by permitted development rights.

Permission may be required if your property is listed, you live in a conservation area or there will be a visual impact on the appearance of the house as viewed from the street. If you are unsure, it is advised that you contact your local planning authority.

Work to install an electric garage door must comply with Part P of the building regulations. This can be done by using an electrician who is registered with the competent person scheme.

‍Visit the website for registered electrical competent persons.

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Verandas will often require planning permission as they do not fall under permitted development rights. If the veranda is raised over 0.3 metres, covers more than 50% of the land around your house, is on the principal elevation or on a roof then it will need planning permission.

You may require additional consents if you live in a Conservation Area or listed building. If you are unsure, you should contact your local planning authority.

For more information about planning permission for verandas and balconies, read our common project.