• any part of the works are higher than the highest part of the roof of the existing house;
• the height of the eaves of the extension would be higher than the eaves of the existing house;
• any part of the extension would project beyond a wall that fronts a highway and is either the principal front or a side elevation of the original house;
• any extension within 2 metres of a boundary would have an eaves height that exceeds 3 metres;
• any single storey extension would project more than 4 metres from the original rear wall of a detached house, or more than 3 metres for any other type of house, or exceed 4 metres in height;
• any extension with more than one storey would project more than 3 metres from the original rear wall of any house, or be within 7 metres of any boundary opposite the rear wall of the house;
• any side extension would exceed 4 metres in height, have more than one storey, or be wider than half the width of the original house;
• the size of all extensions and other buildings takes up more than 50% of the curtilage;
• it would consist of or include the construction of a veranda, balcony or raised platform (above 300mm high)
• you live in a Conservation Area and you wish to extend at the side of your house, or construct an extension with more than one storey;

Development is permitted subject to;

• the use of matching external materials;
• any upper floor windows being obscure glazed and non-opening (unless the opening parts of the window are more than 1.7 metres above floor level);
• any extension with more than one storey having a roof pitch that, so far as practicable, matches the original house

Note:  The term highway includes public roads, footpaths, bridleways and byways.

Building an outbuilding on the land around your house

You need to apply for planning permission to build an outbuilding around your house  in the following circumstances;

• any part of the outbuilding would project beyond a wall that fronts a highway and is the principal front elevation of the original house
• outbuilding would be more than single storey and the eaves would be more than 2.5 metres in height
• overall height would be more than 4 metres with a dual pitched roof, or 3 metres for any other roof, unless the outbuilding is within 2 metres of the boundary, in which case the maximum height is 2.5 metres overall
• structure would be, or would contain, a veranda, a balcony or raised platform
• total footprint of the outbuilding would take up more than half of the area of the land around your house