The Porotherm clay block system is a monolithic wall structure, so no cavity just solid wall. You will use these blocks for your external wall where is the thermal performance is important. Used from DPC (damp-proof course) up to roof plate level and also for gables. Available block sizes (wall thickness): 240mm, 300mm, 365mm, 425mm, 490mm. All block sizes available with or without integrated mineral wool insulation.