Disney plans to do away with traditional piling for some of its buildings at its Hong Kong theme park, alarming a leading architecture expert. Hong Kong Disneyland has opted to use the less expensive raft foundations - a flat concrete base sunk into the soil - for four of its buildings at the $22 billion complex, due to open at Penny's Bay in 2005 or 2006. The company's proposals would mean a departure from the piling method used in almost all reclaimed land projects in the territory. Professor Patrick Lau Sau-shing, of the University of Hong Kong's department of architecture, said the government should be careful over the project's raft foundations. Hong Kong Disneyland confirmed that the raft method would be used for two buildings inside the theme park and two outside. The company said there would be more than 40 buildings at the park. Managing director John Verity said that after an intensive geotechnical and structural investigation of the site he was confident the raft method would work and was safe. He declined to say what the four buildings were and whether they would house rides. Mr Verity said cost was one of many considerations for using the raft foundations. These foundations were commonly used decades ago in Hong Kong but the piling method came into force as buildings became higher. Disney's use of the raft system is believed to be rare on a reclaimed site. Mr Verity argued that raft foundations were ideal for low-rise, lightweight structures such as those in the Magic Kingdom intended for Penny's Bay. 'We attach great importance to safety and make sure all structures are safe and up to local building codes. We have carried out independent tests by certified engineers who have confirmed to us that the load issue is not a concern,' he said. Professor Lau said although Disney's low-rise buildings did not present much of a weight problem for the raft foundation, the 'dynamic force' involved in the mechanical rides contained in any of these buildings should be looked at. A Disney spokeswoman said painstaking assessment showed that even the dynamic load brought by any possible impact from mechanical rides was 'inconsequential'. Professor Lau, who is also a member of the Housing Authority, said: 'There may be more than sufficient data saying that the raft foundation is safe. But look at the piling problems we have had in public housing. Mistakes in foundation work can be disastrous. 'We are talking about a major project for Hong Kong and we invest lots of money in it. The government must be very careful.' The former president of the Hong Kong Institution of Engineers, John Luk Wang-kwong, said raft foundations worked on the principle of making a lightweight building 'float' on a raft of concrete. 'It's like using just the table-top to put buildings on it. If the soil is firm enough, floating it on a raft is okay. Otherwise, piling should be the preferred option,' Mr Luk said. An associate professor of civil engineering at Polytechnic University, Luk Shun-tim, said if a building was light, piles may not be necessary in some cases. A spokeswoman for the Buildings Department said there were no specific government rules covering raft foundations. She said the department had so far approved 17 general building plans submitted by Disney.