Permitted Development Rights for Additional Storeys to a Dwelling

The situation

A homeowner in Tandridge wanted to extend their property upwards, but the house had already been extended once before, at the sides and front. This mattered because the usual rules for permitted development extensions only apply to the ‘original’ house as it was first built, and there wasn’t much of the original structure left to work from. Without another option, the only route would have been a full planning application, with all the extra cost, delay and uncertainty that involves.

The approach

Batcheller Monkhouse’s planning team identified a different route: Class AA, a permitted development right that allows up to two extra storeys to be added above the ‘principal part’ of a house. Crucially, this principal part is defined by the roof’s ridge height, not by when a section of the house was built. That meant the team could build the new storey above the previously extended parts of the house too, as long as they shared the same roof height as the rest of the building.

The outcome

The project doubled the floor area of the original house, with the new upper storey accounting for half of that increase, all without needing full planning permission. It’s also a useful reminder that Class AA works even in the Green Belt, where other kinds of extension can be much harder to secure.