Garage conversion building regulations and planning permission

Planning permission and building regulations are different things

Planning permission is about how a building looks and how it is used in its surroundings. Building regulations are about how it is built: structure, insulation, fire safety, ventilation and drainage. A project can need one, both or neither, and getting planning consent does not mean the building regulations side is covered.

For a garage conversion, the usual position is that planning permission is not needed but building regulations approval is. The exceptions are what make it worth checking your own address first.

Do garage conversions need planning permission?

In many UK houses, converting an attached or integral garage into living space is treated as permitted development, provided the outside of the house is not significantly changed. Planning permission is more likely to be needed where permitted development rights have been removed, which is common on newer estates, where an Article 4 direction applies, or where the house is listed or in a conservation area.

Flats and maisonettes do not have the same permitted development rights as houses. A detached garage converted into a separate dwelling or holiday let is also likely to need planning permission, because the use is changing. If in doubt, a lawful development certificate from the council gives written confirmation that no planning application is needed.

What garage conversion building regulations cover

Building control looks at the whole conversion, but a few areas account for most of the work. The floor usually sits lower than the house and has to be raised, insulated and protected against damp. The walls, which are often single-skin brick or block, need insulating to meet current thermal standards, and the roof or ceiling above needs the same.

The infill where the garage door used to be needs a suitable foundation and must tie into the existing walls. Fire safety is checked too: the new room needs a safe escape route, and integral garages often need the fire separation between the garage and the house reviewed. Ventilation, any new windows and any new drainage for a shower room or utility are also inspected.

• Raised, insulated and damp-proofed floor
• Insulated walls and ceiling
• Foundation and structure for the door infill
• Fire escape and fire separation
• Ventilation, windows and drainage

Full plans or building notice?

Building regulations approval is normally sought through the council's building control service or an approved inspector. A full plans application has drawings checked before work starts, which suits conversions with structural changes or new drainage. A building notice lets work start sooner, with checks made on site, but carries more risk if something has to be changed after it is built.

Either way, inspections happen at set stages, such as when the foundation is dug and before the floor and walls are covered. A completion certificate at the end is the document a buyer's solicitor will ask for if you sell.

When the approvals are clear, see how we plan the build on our garage conversions page.

For a breakdown of what affects the price, read the garage conversion cost guide.

Common questions