The biggest group of homes in the Sunderland council area was built between 1945 and 1964. This is the period when asbestos use in British building was climbing steeply, so original materials are more likely to be present rather than added later. Roughly 86.6% of the 135,520 properties here predate the 1999 ban, and the largest group by type is semi-detached houses at 33.5%. In semi-detached housing the most common finds are asbestos cement garage and shed roofs, textured coatings on ceilings, insulating board in airing cupboards and around boilers, and cement soffits and rainwater goods. The next largest group is terraced houses at 26.6%, where party walls and shared roof spaces mean neighbouring work can disturb material next door. By period, 14.2% were built before 1900, 13.9% between 1919 and 1939 and 13.2% since 2000. None of that tells you whether a particular property contains asbestos; only a survey or a laboratory test can.