Yes, but you will need to obtain planning permission. Converting a detached garage into a self-contained living space, such as annexe, studio flat, or retail unit, represents a material change of use, particularly if it will function independently from the main house. This is because the garage would no longer be used in connection with the main dwelling and would effectively become a separate residential unit.
There are different planning fees for England and Wales, and many different application types depending on the work being carried out.
You can use the Planning Portal's fee calculator to work out fees for different kinds of proposal.
Use the fee calculator (England)
Use the fee calculator (Wales)
While every effort has been taken to ensure that the fee has been calculated correctly, the determination of whether a planning fee is correct is the responsibility of the relevant local planning authority, who will check the fee is correct when the application is submitted and validated.
If you're doing electrical installation work in your home or garden in England or Wales, you must follow the building regulations. It's recommended to hire an installer who is registered with a competent person scheme (a registered competent person’) who can self-certify that the work meets the required standards.
Foundations are required to carry and distribute the load of the building safely. Therefore, all buildings should have adequate foundations. The factors that need to be considered when designing a foundation are:
It is advisable to contact a structural engineer or speak to a building control body about plans for new foundations.
Read more about foundations for extensions
If you plan to put up a small, detached building like a garden shed, garden room, garden office, annexe or summerhouse (all classed as outbuildings), building regulations generally won’t apply if the building has a floor area under 15 square metres and does not include any sleeping accommodation.
For buildings with a floor area between 15 and 30 square metres, building regulations approval is usually not needed - as long as the building does not include sleeping accommodation and either:
Read more about the building regulations that apply to outbuildings.
Don't forget to check the permitted development rights for outbuildings.
The conversion of a garage, or part of a garage, into habitable space, will normally require approval under the building regulations.
As part of the garage conversion, it is likely that the original garage door will be in-filled with a new wall and possibly a window or door, and a new foundation may be needed for the new wall.
As well as the foundation, you also need to consider:
Read more about the building regulations for garage conversions