Orlit concrete houses are made of precast reinforced concrete (PRC). House design was made by Czech architect Erwin Katona. Over time, PRC deteriorates, particularly at construction joints and junctions between components, with a gradual reduction in structural effectiveness. Also, this material often suffers from inadequate overall thermal insulation, as well as thermal bridging and subsequent condensation problems. In Scotland, the Orlit house type was designated as defective under the Housing Defects Act 1984. Most of them were built in the UK during the '40s and '50s postwar period as a quick and cheap solution, but the majority have needed major repair work or have been demolished since. Most UK lenders will not give any form of mortgage for them.