Experts Say NEX Ventilation Duct Incident Could’ve Been Due To Weak Support

By now, we know that the cinema at Nex was temporarily closed because a ventilation duct fell through the ceiling last Sunday, 30 Aug, resulting in two victims being rushed to the hospital.

Industrial experts claim that it was possibly a result of weakening duct supports, such as loose nuts and bolts or spalling concrete slabs, reports The Straits Times.

Possible reasons for the collapse of ventilation duct

Associate Professor Daniel Wong from the Department of Building at the National University of Singapore’s School of Design and Environment said that the duct is usually bolted to metal rods that are secured to a concrete ceiling slab.

According to Prof Wong, there are three main possibilities for what caused the ventilation duct to fall:

1. A damaged rod
2. Loose or faulty nuts and bolts
3. The concrete slab is beginning to rust or break

“However, based on the photos of the dislodged duct, it seems that the metal rod is still intact and remains connected to the duct, so there is a higher possibility for the other two scenarios,” he said.

As a veteran who has been involved in the projects and facilities management industry for over 20 years, Prof Wong said he has only seen three or four cases of ventilation ducts becoming dislodged.

In those cases, the rod was accidentally hit during cleaning, or nuts and bolts that had been removed during maintenance had not been securely tightened.

To prevent such accidents, Prof Wong said that these parts have to be regularly replaced once their product life cycle has been met, and carrying out regular inspection can early detect wear-and-tear.

According to The Straits Times, project manager Zaw Myo Lwin, who works at a local air-conditioning maintenance company, noted that the metal rods attached to the ducts are typically able to carry a weight of between 50kg and 100kg.

However, based on the photos of the dislodged duct at Shaw Theatres Nex, its likely weight for its size is around 20kg, he said.

He suspects that it was the drop-in anchor, a type of fastener which secures the duct to the concrete, that became loose.

Follow-up from NEX and Shaw Theatres

The Building and Construction Authority (BCA) had sent an engineer to investigate the incident on the same day at 6:30pm, around 2 hours after the collapse occurred.

Shaw Theatres was closed during that period of time.

BCA has also appointed a professional engineer to conduct a more thorough investigation of the incident as well as to inspect the other ducts.

In the meantime, if you’re interested to know more about what’s installed in your ceilings you can read more about ventilation ducts over here.

Even though this appears to be a freak accident, I’m guessing that all future movie-goers and cinephiles will probably be extra wary of what’s above them.