Small Studio Construction

I am building a small studio in my garden. It's a wooden construction about 3m by 3m in plan. My neighbour seems to be annoyed by the works and she says I need planning permission. Is she right?

The rule of thumb is that garden buildings, including studios, do not generally require planning permission, as they are deemed to fall into 'permitted development' but there are a few provisos that do apply. Your studio must not be placed less than 2 metres from the boundary of the property and the maximum overall height cannot be more than 2.5 metres from the existing ground level. It must also not provide sleeping accommodation and must be a single storey. A further proviso, which many people don't remember, is that your studio cannot be larger than half your garden, without having to obtain planning permission.