Hi - we want to install a solid slab reinforced concrete foundation, flat with no edge thickening, concrete 200 mm or less, on uniform 200 mm expanded PS with 200 mm perimeter EPS to the top of the slab. The ground under topsoil is a solid chalky clay bed with no known adverse effects for buildings across the surrounding region. The building is to be a 38 × 89 mm factory timber frame of simple design with tiled roof over one and two storeys, with lightweight external trusses of the Larsen type to master the EPS perimeter upstand. We have quotes from some of the German/Scandinavian prefabricated EPS foundation system suppliers. They are fairly expensive, and some include transport costs from Europe and visiting erection teams. We are interested in a built-up version of the foundation, using EPS of appropriate strength, with reinforcement to suit, designed by a UK engineer interested in such a system and able to minimise concrete and keep a flat base while satisfying local BC. We feel sure it can be done; there are examples on the web from Canada etc. Any suggestions or pointers - for both system detail and engineering - gratefully received. We are aware of earlier posts (e.g. topic ‘Thermally efficient foundations’) but would like to update.