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.

Building a porch at ground level and under 30 square metres in floor area is normally exempt from the need for building regulations approval.

This is provided that glazing and any fixed electrical installations comply with the appropriate sections of building regulations.

To find out more about the building regulations for porches, visit Planning Portal.

Find out more about glazing and electrical installations

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Yes, in most cases you can use an outbuilding as a home office without needing planning permission. As long as the use remains incidental to the main dwelling it is still considered part of your domestic residential use.

Read more about outbuildings

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Adding an internal wall will not require planning permission or building control approval in most cases. If the building is listed, then you may require listed building consent to make a major alteration to the house.

 Any work completed should adhere to building regulations, ensuring fire routes, electrics and ventilation are considered.

Removing a non-load bearing wall will likely not require building control approval provided it does not affect fire escape routes, ventilation, drainage or electrics.

It is best practice to get a report from a structural engineer to ensure the wall is non-load bearing prior to starting any work.

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