Home owners have told the BBC they are living in fear of crippling bills after finding out a cheap version of concrete that could be at risk of collapse was used in their houses. Reinforced autoclaved aerated concrete (RAAC) was used mostly in flat roofing, but also in floors and walls, between the 1950s and 1990s. It has been found in public buildings across the UK sparking fears about the potential collapse of ceilings and walls - and many local authorities are now moving to inspect council houses. But whereas current tenants are having their repair costs covered, many people...