Square metre costs cover the cost of building a house from foundations to decoration, including standard bath and kitchen fittings and everything else to make the house fit for occupation. It’s measured from the inside of the external walls across internal walls, partitions, chimney breasts and stairwell openings, with the ground and first floor areas added to produce a total area. (See page 140 of Build It, January 2009 for a detailed cost breakdown of building your own home)