Falling ventilation duct at Nex: Duct maintenance not subject to regulatory requirements, says BCA

BCA has instructed the cinema to be closed for a thorough check. PHOTO: LIANHE ZAOBAO

SINGAPORE - The maintenance of air-conditioning mechanical ventilation (ACMV) ducts within buildings is not subject to regulatory requirements, said the Building and Construction Authority (BCA) in a statement on Wednesday (Sept 2).

In response to queries by The Straits Times, a spokesman for BCA added that "building owners are responsible for the maintenance of their buildings, by ensuring that all parts of their buildings are maintained in a state of good and serviceable condition".

This includes the "maintenance of interior fittings such as ACMV ducts".

On Sunday at Nex shopping mall, a falling ventilation duct at the Shaw Theatres cinema injured two patrons.

BCA has since instructed the cinema to be closed for a thorough check, and investigations by a professional engineer appointed by the building owner are ongoing.

A spokesman for Nex said that "all maintenance of various mechanical and engineering systems for the common areas in the building are carried out according to a planned schedule by appointed specialist contractors".

"In addition, when the maintenance team onsite observes any abnormalities in the course of their work of these systems in the common areas, they will conduct further inspections or checks to determine the cause and take appropriate actions," he said.

The shopping mall is co-owned by Mercatus and Gold Ridge, and managed by the latter.

Associate Professor Daniel Wong from the department of building at the National University of Singapore's School of Design and Environment said the maintenance of duct systems in buildings tends to be very ad hoc and infrequent, owing to the high costs involved and the disruption it causes.

"The suspended ceiling has to be cut open for inspection and cleaning of the duct systems, which are conducted separately - and this is usually very disruptive, hence it is done infrequently," said Prof Wong.

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He said some companies avoid doing maintenance work for as long as five to 10 years.

Ideally, the inspection of duct systems should be periodically scheduled as it is not possible to complete the entire inspection at one go, since it can stretch throughout the building and across multiple floors, Prof Wong said.

Instead, various rooms or floors are divided into a routine for checking, and it could take more than a year for the entire inspection to be completed.

In addition, the thorough cleaning of duct systems would cost at least $30,000 and may be too expensive. As such, companies typically clear essential or heavy-use areas, though he said that the frequency of their cleaning varies, depending on the company.

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