19 Feb 2020

Fire tests of cladding are under way in NZ in response to the Grenfell Tower tragedy

11:38 am on 19 February 2020

Fire tests of cladding on multi-storey buildings are being run in New Zealand for the first time in response to the Grenfell Tower disaster in London.

The test methods themselves are getting the once-over at a purpose-built rig near Porirua; next, wall assemblies themselves will be set alight to see how they burn.

There hasn't been a way to run international tests locally to determine the fire-safety of the type of walls commonly constructed with New Zealand quirks and to local conditions, till now.

"Grenfell really motivated change in terms of how we look at facades," fire engineer Dr Kevin Frank said.

Plenty has been reported about the plastic-filled cladding to covering a building in solidified petrol that fed the flames at the London apartment block in 2017, killing 72 people.

But it was also the combustible insulation, the frame, the way it was all put together, that fed the flames.

"So what we really learned from Grenfell that was different from a lot of the other fires before, is that we need to look at the outside of buildings as a system, rather than looking at individual components," Frank said.

"And what that means is that we need to go to bigger tests."

His team has built an 9m-high rig on a concrete pad among paddocks at the Building Research Association or Branz in rural Porirua.

They are running full-scale facade fire tests, initially to evaluate international testing methods based on the British and Australian standards.

"New Zealand's never run tests like this before, this is the first time it's been available in New Zealand."

A 1.5-metre crib of wood battens is set alight at the bottom of the rig. Within minutes the flames are licking the bottom of the non-combustible test wall; and shortly after are five metres high. If the temperature exceeds 600 degrees five metres up the wall, it's a fail.

The rig is big, and the problem is daunting: How to assess the many types of cladding being put on new buildings now, let alone the hundreds of buildings nationwide that have Grenfell-style highly combustible or semi-combustible aluminium composite panels.

The problem is not just that these panels were tested in isolation of the wall assemblies they would be part of.

Also, the certificates for most of the Grenfell-type cladding in use in New Zealand were weak on fire evidence, and the Ministry of Business, Innovation and Employment (MBIE) knew that the major certifiers were not doing a good job, as RNZ investigations over several years have revealed.

Lessons still being learned

The inquiry in London into what went wrong with construction at Grenfell is dragging on, long after the hard-pressed firefighters, who were an easier target, got a grilling.

The lessons are still coming in and not only engineers, but regulators like MBIE are still coming up to speed with them.

RNZ asked the ministry for any update on how many buildings had been found to have aluminium composite cladding like Grenfell.

MBIE said in a statement it had not required councils to do anything further since Auckland, Wellington and Christchurch reported their initial counts in 2018.

"Territorial Authorities [councils] may have continued their programme of ACP identification and analysis - MBIE does not have specific details of the TA activity, and is not aware of any agency currently collecting data," it said.

High-rise fires globally had increased the understanding of how fire spread externally and within modern facade construction, it said, so it was time to reconsider the rules to include international tests as a means of demonstrating compliance.

"We expect that these proposals will provide a clear path on what fire testing is required for regulatory compliance."

The cladding ructions the UK and Australia, where much more highly flammable panel was used, are far greater than in New Zealand, where the back-up protection systems such as sprinkler systems are more heavily regulated.

In the UK, the second phase of the Grenfell inquiry began with cladding company and contractor requests that nothing they say be used against them in any future criminal prosecution.

Emails disclosed to the inquiry suggested that companies knew a planned cladding system would fail in the event of a fire.

In Canada, the government is looking at naming and shaming building owners who haven't taken action over combustible panels, "unless swift progress is seen".

It is also looking at financing options to "ensure that cost is not a barrier to remediation".

Fire testing expected to be in demand

Frank expects the Porirua set-up will eventually be in demand by businesses to test all sorts of wall designs, and to also give regulators a better idea about local designs tested overseas.

"Right now we're just evaluating the test methods... What we'll do in the future is build construction is more like how New Zealand buildings are really built, and then look at how fire spreads over that construction.

"Comparison to Grenfell, probably less [combustible] because you don't tend to get the combustible insulation, but that's what the research is all about, to understand how our buildings compare."

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