Every pile drilled by contractors on private housing sites will be checked in a new crackdown that will increase tests by up to 20 times. A new registration system will also be set up to ensure quality of site surveys, the Buildings Department announced yesterday. The measures will require foundation works to be supervised by four qualified engineers, two of whom will be on site full-time. The cost of piling will rise by around two per cent because of the new requirements. However, government housing sites, where a series of defective piling scandals have been uncovered over the past year, will be exempt from the 100 per cent testing policy. Director of Buildings Leung Chin-man said these sites were under the jurisdiction of the Housing Authority, which is also reviewing its procedures. At present, contractors check as few as five per cent of piles in random tests, according to the Institution of Engineers. The institution's Dr Greg Wong Chak-yan welcomed the measures as a 'great improvement'. He estimated about 200 sites were at the foundation stage at present and contractors would have two months to fulfil the new requirements. He believed there would be an adequate supply of specialist engineers for contractors to meet the rules. He warned that contractors failing to comply would face having their works halted immediately. Kent Lee Wing-kan of the Real Estate Developers Association said: 'It might delay works a bit because of the extra checks, but the Government has promised to cut red tape in other areas to help us catch up.' The measures are the outcome of a six-month study by a Buildings Department working group. Major recommendations include: Setting out the duties of engineers, specialists and site supervisors in supervision of building work; Specifying the tests and frequency of checks for foundation works and ground investigation work; and Formulating test requirements for pile foundation works.