Spot checks on building sites by government engineers will replace pre-arranged inspections in an effort to crack down on errant contractors and substandard work. 'Unpredictability is the centre of this new strategy. They will not know when we go and what we check,' the Director of Buildings, Leung Chin-man, said yesterday. He said the aim was to achieve more effective on-site auditing to improve quality and safety standards. Piling work would be inspected during working hours instead of only at the beginning and the end of work as is the practice now. Auditing staff would be rotated to 'minimise subjectivity' in the inspection of the same site. Contractors and the department would save time and money fixing substandard work if it were found earlier, said Mr Leung. A rating made after an initial site audit would determine the timing, frequency and focus of subsequent checks. Factors checked would include on-site organisation, qualifications of supervisory personnel, and completion of work records. Mr Leung said foundation work sites rated as satisfactory would be inspected about every two months and superstructure sites about every four months. Sites that failed to meet standards would be visited every one to two months. Existing manpower broken into two teams of 22 inspectors would be enough to handle the work despite the push for higher standards, he said. Two more teams would be added in the middle of the year as a result of increased funding, Mr Leung said.