Moves to regulate engineers, change Building Code for hollow-core floors

The collapse of the CTV Building in the 2011 earthquake highlighted the risks of inexperienced...
The collapse of the CTV Building in the 2011 earthquake highlighted the risks of inexperienced engineers working in high-risk engineering fields. Photo: Star News
A change to the Building Code is being proposed after the Kaikōura earthquake resulted in widespread damage to buildings with hollow-core flooring.

Meanwhile, Cabinet has agreed to a new regulatory regime for engineers, meaning they will have to be registered and subject to a code of conduct.

"The collapse of the CTV Building in the 2011 Christchurch earthquake highlighted the risks of inexperienced engineers working in high-risk engineering fields and the difficulty in holding substandard or unprofessional engineers to account," a Cabinet paper from earlier this year said.

Both the Kaikōura and Christchurch earthquakes have led to a seismic shift in how engineers understand building performance, the regulatory effects of which are still emerging.

Hollow-core floors are a type of pre-cast floor which were increasingly popular from the early 1980s because they were fast to construct and cost-effective.

They have hollow tubes in the concrete units making them lighter than solid concrete floors. The units are manufactured offsite, then craned in to sit on the building's beams and walls, and a thin mesh concrete topping is applied over them.

However, cracks were discovered in the floors of many buildings across Wellington with these type of units following the Kaikōura earthquake.

Even the BNZ building, completed in 2009, showed cracks, the Ministry for Business Innovation and Employment (MBIE) said in a consultation document.

"This reaffirmed that even modern hollow-core floor systems are vulnerable to excessive damage during earthquakes, some beyond economic repair potentially impacting building function and health and safety of occupants."

BNZ's former head office on Harbour Quays was badly damaged in the Kaikōura earthquake and has...
BNZ's former head office on Harbour Quays was badly damaged in the Kaikōura earthquake and has since been demolished. Photo: Mark Mitchell
The BNZ building has since been demolished.

A subsequent study from 2018 said the use of hollow-core floors in new buildings was not considered good structural engineering practice and was not recommended.

MBIE building performance and engineering manager Dave Gittings said the proposed change will require engineers to go over and above the existing design method for hollow-core flooring.

"We expect that engineers and designers looking to use these types of floors would be required to provide additional evidence (testing and analysis) to demonstrate that the design of the support complies with the Building Code as an alternative solution."

Gittings said MBIE expected the proposed change will minimise the chance of excessive damage or injury from poorly designed hollow-core floor systems in future earthquakes.

Engineering New Zealand chief executive Dr Richard Templer said the organisation will make a submission on the proposal once it has consulted with members.

"However, we know hollow-core units have known fragility issues and numerous failure mechanisms."

MBIE's consultation on the proposed amendments to the Building Code runs until 1 July 2022.

Separate to this, the Government is moving to regulate engineers themselves.

Officials estimate around 38,000 engineers are not subject to any occupational regulation.

"Without occupational regulation and the checks and sanctions it involves, there is a risk that substandard engineering work will lead to catastrophic failures, harm to the public or the environment, significant economic costs, and damage to the public's confidence in the engineering profession," the Cabinet paper said.

Poto Williams. Photo: NZME
Poto Williams. Photo: NZME
A new two-tier regime is being designed that will require anyone providing professional engineering services to be registered. A new regulator will be established to oversee the regime.

Building and Construction Minister Poto Williams said there was lack of clarity around who could call themselves an engineer making it difficult for consumers to know whether an engineer was qualified to practice.

"The registration requirement will lift the professionalism of the engineering profession and provide an avenue for addressing poor behaviour and performance."

Engineers will also be subject to a code of conduct and there will be new licensing requirements to restrict practice in high-risk engineering disciplines.

"Officials are currently developing a bill which I look forward to taking to the House later this year," Williams said.

-By Georgina Campbell

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