Do I need Planning Permission to extend my house including building a conservatory to the rear,or to convert a garage, store or shed at the rear or side of my house for use as part of the house?

No, if the following apply:

• If the house has not been extended previously, the floor area of the proposed extension shall not exceed 40 square meters.
• If the house is terraced or semi detached the floor area of any extension above ground level shall not exceed 12 square meters. If the house is detached this figure will be 20 square meters.
• If the house has been extended previously, the floor area of that extension or any extension constructed after 1st October 1964 taken together with the floor area of the proposed extension shall not exceed 40 square meters.
• In the case of a terraced or semi detached house the floor area of any previous extension above ground level taken with that of the proposed extension above ground level shall not exceed 12 square meters. In the case of a detached house this figure will be 20 square meters.
• Any above ground floor extension must be a distance of not less than 2 meters from any party boundary.
• If the rear wall of the house does not include a gable* the height of the walls of the extension shall not exceed the height of the rear wall of the house.
• The height of the highest part of the roof of the extension shall not exceed the height of the highest point of the house. In the case of a flat roofed extension the height shall not exceed the height of the eaves or parapet, whichever is appropriate.
• The construction of an extension shall not reduce the area of private open space (reserved exclusively for the use of the occupants of the house) to the rear of the house to less than 25 square meters.
• Any window at ground level shall not be less than 1 metre from the boundary it faces. Any window above ground level shall not be less than 11 metres from the boundary it faces.
• Where the house is detached and the floor area of the extension exceeds 12 square metres ,any window proposed above ground level shall not be less than 11 metres from the boundary it faces
• The roof of any extension shall not be used as a balcony or roof garden.

* a gable is the upper part of a wall (normally triangular), between the sloping ends of a pitched roof.