Height:
A garden office must be single-story with a maximum eaves height of 2.5 meters. The overall height, including the roof, can be up to 4 meters for a dual-pitched roof, or 3 meters for any other roof type, unless it's within 2 meters of a boundary, where the overall height is limited to 2.5 meters.
Location:
The garden office cannot be placed forward of the principal elevation of the house (generally the front of the house). It also cannot be closer to a public road or footpath than the main house.
Coverage:
The total area of buildings, including the garden office and any other existing outbuildings, cannot cover more than 50% of the land surrounding the "original house" (which includes any extensions or outbuildings built on the property since 1948).
Use:
The garden office can be used for a variety of purposes like a home office, study, or workshop, but it cannot be used as a living accommodation, such as a bedroom or a self-contained dwelling.
Exceptions:
If the garden office is used as a sleeping accommodation, it will require planning permission. Also, if it is within the curtilage (the grounds) of a listed building, planning permission will be required.
In summary, a garden office can be built under permitted development in London, but it must comply with the specified height, location, coverage, and use restrictions. If any of these rules are not followed, you will need to apply for planning permission.
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