A conversion and first floor extension of an existing single storey science block to provide additional general teaching classrooms and to upgrade the existing external fabric. A unique design involves a new structural table sitting over the existing building that allows the classrooms to remain in use whilst the first floor is completed. The ground floor windows and walling are replaced to match the first floor during the summer recess. The final outcome will appear to be a completely new building externally whilst containing pre-existing accommodation in a seamless envelope.