HOUSING AND DEVELOPMENT BOARD FLATS (Quality of repair to spalling concrete)

Mr Low Thia Khiang asked the Minister for National Development yhow the Housing and Development Board (HDB) ensures the quality of the repair to spalling concrete and how it determines whether defects in HDB flats are caused by natural deterioration of building material over time or due to poor workmanship during construction.

Mr Lim Hng Kiang: Mr Speaker, Sir, HDB ensures a high quality of repair works to spalling concrete by adopting repair methods and approved materials which adhere to stringent international standards. HDB uses a pool of competent local contractors who employ trained workmen to carry out the repair works. HDB also conducts systematic on-site supervision and carries out random testing of materials used to ensure that these high standards are met.

Spalling concrete defects are usually caused by natural deterioration of building materials, misuse or under-maintenance. All building materials deteriorate over time. Spalling concrete is due to a natural deterioration process called carbonation. HDB's trained technical staff is able to determine the cause of defects by carrying out both on-site as well as laboratory tests.

Mr Low Thia Khiang: Sir, is the Minister aware that the same problem of spalling concrete recurred again after it was repaired by the HDB's contractor and will HDB provide a warranty period after the repair?

Mr Lim Hng Kiang: If a section of the ceiling affected by spalling concrete has been repaired by HDB's term contractors, it comes with a warranty. And if there is a failure in the repair method, the contractor will have to go back and make good the repair. This is very rare because the method of repair is a standardised method. The material they used has got chemical bonding as well. So the chance of recurrence of defects after the repair is very, very slim. If Members have specific cases, they can write to HDB's branch office and the contractor will be required to re-do the job. But I can assure Members of this House that any repair method by HDB's term contactors generally does not fail a second time.

Mr Low Thia Khiang: Sir, how long is the warranty period?

Mr Lim Hng Kiang: I do not have the specific warranty period. But if any residents face defects in the area that has been repaired by HDB's term contractors, I think they should just refer the case to the branch office and it will take steps to remedy the situation. But, again, I assure Members that this is not a big situation, and that is why I do not have the numbers.

Mr Low Thia Khiang: Mr Speaker, Sir, I hope the Minister will make public the warranty period provided by the HDB for repairs to spalling concrete.

Sir, would the HDB admit that the possible cause of spalling concrete is due to BRC reinforcement insufficiently supported by spaces or the displacement of spaces during the construction stage which resulted in improper concrete coverage and, under the circumstances, there is no proper bonding and corrosion-resistant to the reinforcement? I think that could be the cause of the spalling concrete over time.

Mr Lim Hng Kiang: Mr Speaker, Sir, as I said, whenever there is a case of spalling concrete, HDB's technical officers will go to the site to inspect. Generally, if the spalling concrete occurs in small patches, then it is not likely to be a workmanship problem because such a problem is either due to poor spacing or lack of coverage by concrete has to be over an extended area for that poor workmanship to take effect. Generally, spalling concrete occurs in the wet areas, for example, kitchens or toilets, because the higher rate of moisture and carbon dioxide results in the deterioration of the concrete much faster than in other areas, for example, the sitting rooms or bedrooms. That is why all home owners must maintain the kitchen and toilet areas more regularly than the other areas. A typical mistake of most Singaporeans is that they will paint their house once every three or four years and they treat the bedroom area in the same manner as the kitchen area. I think this ought to be changed. It is more prudent to paint the ceilings of your kitchen and toilet more regularly rather than wait till you are painting the whole house.

The Member mentioned that if the spacing between the reinforced bars is insufficient, then spalling concrete will occur. That is possible, ie, the thinner the concrete cover, the greater the chances that carbonisation will take place and the quicker the moisture will reach the steel bars, therefore causing corrosion and spalling concrete. So if it is a widespread spalling concrete, HDB's technical officers will take a look and check whether the concrete cover is according to the design criteria. If it is according to design, then obviously there is no workmanship problem. But in very rare cases where the spaces are not followed, then it could cause spalling, in which case, the defect will be very widespread. Again, this is very, very infrequent.

Mr Low Thia Khiang: Would the HDB make public its detailed specifications on concrete for construction, the required space in between the steel bars and things like that?

Mr Lim Hng Kiang: I think specifications on the spacing of reinforcement bars and concrete coverage are generally available in the design code and in the tender specifications of HDB contracts. These are standard requirements in all HDB contracts.

Mr Low Thia Khiang: Is the Minister saying that if it is proven that the space is insufficient as required or does not comply with the specifications, the HDB will repair the spalling concrete free of charge?

Mr Lim Hng Kiang: Mr Speaker, Sir, the way we have structured the spalling concrete co-payment system takes care of this. If it is a case of poor workmanship, we will expect the spalling concrete to occur over a very wide area. In this scheme to co-pay for the repairs to the defects, HDB has put a cap of $300 to be paid by the residents. This means that if it is a widespread area and probably due to workmanship problem, then the residents only pay up to $300 and the rest will be covered by HDB.

Mr Chng Hee Kok: The Minister confirms that this problem of carbonisation is common among all buildings in Singapore and not just HDB flats. In relation to the total number of flats built by the HDB, how does this problem of spalling concrete compare in the private sector?

Mr Lim Hng Kiang: Spalling concrete as a result of carbonisation affects all concrete buildings, both public as well as private homes. In HDB's case, because we take greater care in the maintenance of the buildings and the residents have recourse to report such cases to the HDB's branch office, we capture the statistics more regularly. The private homes do not have to make this report. If they see spalling concrete, they just go and hire a contractor and repair it. Therefore, the Ministry has got no data on spalling concrete in private homes. There is no requirement that they report to us. If they report to us, we are not going to pay for them. But in HDB's case, we over-indulge in looking after HDB flats. They call on us and we help them find term contractors or we pay. That is why we collect these statistics. It is a common occurrence. It happens in my own house and we have to paint and repair it. I do not go and call the HDB's branch office.

Mr Chng Hee Kok: Sir, in other words, the Minister says that in the case of private homes, beyond the defects liability period, owners are supposed to carry out repairs on their own.

Mr Lim Hng Kiang: The Member is absolutely right. In private homes, you have a one-year defect liability period during which the developer will make good any defects discovered during that period. Beyond that one year, you have to make good any defects that occur in your homes. In HDB's case, after 20 years, if you have a spalling concrete problem, you report to the branch office, HDB's technical officers will still come to your house, take a look, and advise you what to do.

Mr Low Thia Khiang: Sir, if there is spalling concrete in HUDC flats, would the HDB repair the spalling concrete before they are privatised?

Mr Lim Hng Kiang: The answer is no.