Even for the largest businesses and the most professional contractors, things can still go wrong, take a look at these:
New Wembley Stadium
40 foot crack through three floors following an overnight storm
Scottish Parliament building
7500 defects identified. A 12 foot beam fell down during a parliamentary session
Charles De Gaulle Airport
Terminal 2E collapsed - 5 people killed in 2004
Wimbledon Media Centre
£4.6 million writ over defects
Clissold Leisure Centre
Costs of £34 milion. 59 defects occurred in the first 18 months of the building being open
South London
In 2007 black mould growing in three year old luxury apartments. Over £12 million then and expected to rise.