This project by Bradley Van Der Straeten Architects (BVDS) is called Two and a half storey house because the new roof extension sits no higher than the existing roofline of the building and is hidden from the street elevation.

The house is located on a housing estate in Stoke Newington, London and is part of a terrace of houses. It had 2 bedrooms and the clients, a family with their second child on the way, needed an extra bedroom so BVDS were appointed to try to come up with a solution. Prior to this the client had made two planning applications to add roof extensions both of which had been refused. BVDS managed to circumnavigate the height restrictions by using an interlocking section and half levels to create a half storey in the loft space with a mezzanine sleeping area, this was done under Permitted Development rights and without the need for planning.

The height of the new roof extension was set to match the highest point of the existing roof and then the volume within this was cleverly manipulated to tease out an extra half storey by lowering the ceiling on the first floor over areas that didn't need to be full height such as storage space and wardrobes, this gave adequate floor area to the new floor above for a dressing area at the end of the raised platform bed which is positioned over the higher part of the ceiling on the first floor.

The result is a successful light, bright and fun bedroom with plenty of integrated storage. Roof lights are strategically placed to create a sense of height as well as to bring light in, there is one over the main staircase which illuminates this plywood lined space and integrates all the floors together. The use of simple materials accentuate the sense of space, plywood and white painted walls allow the light to bounce around whilst also giving the space a warmth through the natural textures and grain of the wood.

To maximise floor to ceiling heights, the construction is predominately framed in steel and the steels used are tall and narrow so the they can be hidden in the thickness of the walls this means that they do not influence the depth of the floor construction. The steels are positioned to limit the spans of the timbers to keep them as slim as possible and the timbers are exposed to further increase the sense of space, they are supported on concealed joist hangers for a clean look. The thickness of the roof is kept to a minimum by using ultra thin vacuum insulation panels.

This project is an excellent example of how employing a good architect can help overcome a seemingly impossible situation with a clever, elegant solution.

Two and a half storey house has also won the Compact Design of the Year prize from the 'Don't Move Improve' Awards which are organised by New London Architecture.