from rot, can be found in the footings of the structure where it meets the foundation slab. With checks undertaken by a qualified building surveyor, the structural integrity of the house can be quickly ascertained through exposure of the footings: if they are not rusty or rotted, the house is normally structurally sound. The second problem with non-refurbished houses is the use of asbestos in the original construction, particularly in the roof structure. Again, a qualified surveyor should be able to ascertain if asbestos is present, what type, and how to address its removal. There are a number of central and local government grants available for domestic asbestos removal which should cover most of the cost. The third problem with the survival of prefabs in the 21st century is that of style. Never seen as aesthetically pleasing, the tight building regulations meant they also came with reasonable-sized rooms and gardens. Modern house construction can create around 35 living spaces per acre, while often the prefabs will form site layouts of fewer than 20. This, together with the age of the properties, makes redevelopment of mass prefab sites a distinct advantage to councils and housing associations. Hence, every year since 2000, the number of prefabs remaining has approximately halved. Preservation Bristol has one of the largest remaining populations of prefab housing stock, which also remains one of the most diverse. A wartime production centre for aircraft, engines and explosives, it was easy to reach for Luftwaffe bombing, and hence had a large post-war need for new housing stock. There remain around 700 examples of Uni-Seco, Phoenix, Tarron and roll-topped Arcon Mk Vs. The stock diversity has resulted in English Heritage selecting 16 prefabs for Grade II listed building status. The Excalibur estate in Catford, London Borough of Lewisham is the UK's largest remaining estate of post-WW2 prefab houses, with 187 Uni-Seco wooden frame bungalows plus a flat-roofed prefab church. While residents fought to save the entire 187-unit estate, English Heritage wanted to save 21 examples, and the council, which still owns 80% of the properties, wanted the ability to demolish the whole estate. In September 2009, the Department for Culture, Media and Sport agreed to Grade II list six of the least altered properties. Similar debates have resulted in the listing of 16 Phoenix prefabs in Wake Green Road, Hall Green in Birmingham; and two in Doncaster. Approximately six prefabs have