This type of conversion is a good one for urban areas or can sometimes be appropriate for conservation areas as it usually built at the back of a property. The Mansard usually means changes to the roof structure and it has a flat roof with a back wall sloping inwards. It provides a lot of space but because they involve change to the property structure they can be a more expensive option. The windows are built in as small dormers and the walls on either side complement the existing brickwork.