Older versions WikiHouse Skylark might be our latest building system but before Skylark there were other versions of the system, each named after a different bird. Here we explain each name: Skylark 200 Skylark 200 is 250’s thinner sibling, for use in small, single storey structures (micro offices, gyms, garden workshops etc, with a height below any planning limits). As the name suggests, the standard insulation depth in the walls is 200mm. Skylark 250 Skylark 250 is the main WikiHouse building system. It is intended for use in 1-3 storey detached buildings. The number 250 simply refers to the thickness of insulation in the walls.