SPALLING CONCRETE IN HDB FLATS

Dr Ong Seh Hong asked the Minister for National Development (a) what is the extent of the problem of spalling concrete in HDB flats, especially those flats built during the "accelerated programme" years in the 1980s; (b) what are the plans, if any, to help rectify the affected flats; and (c) whether his Ministry will consider extending the HDB grant to subsidise the repair cost of spalling concrete.

Mr Mah Bow Tan: Spalling concrete is the result of a deterioration process called carbonation whereby carbon dioxide diffuses into the concrete and forms carbonates when it reacts with the alkalis in the concrete. Carbonation reduces the level of alkalinity in the concrete, thus allowing the steel bars in the concrete to corrode. The corrosion causes the steel bars to expand forcing the concrete surrounding the steel to crack and spall, exposing the steel bar.

Spalling concrete is a natural phenomenon and it occurs in all concrete buildings as the buildings age over time. It is not peculiar to any flat type or flats which were built in certain years or during a certain period.

HDB flat owners who encounter spalling concrete problems in their flats can report them to their respective HDB Branch Offices. HDB will assist the flat owners to investigate the cause of the problem and recommend appropriate remedial action. For flat owners who have difficulty in finding a suitable repair contractor on their own, HDB will also assist to provide them with a list of repair contractors for them to negotiate with on a private basis.

Under the lease, HDB flat owners are responsible for the repair of spalling concrete in their flats. As such, the Government cannot subsidise the repair cost for spalling concrete problems.