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Non-compliant external cladding: The Implications for fire rating

Oct 22, 2020

In this article, we will delve into an area not well explored and look at the link between cladding issues, their fire risks as well documented in Australia, the impact on the building and as a result, the different mitigation measures that you can employ.
 

What is cladding?

Our sister company Remedial Building Services has written on numerous occasions about the role and risk of external building cladding and what it is exactly. But as a quick recap, the extra non-load bearing layer on the exterior of a building is referred to as cladding. Much the same as a skin, it can be attached to the framework of a building or a transitional layer of battens or spacers. Its purpose is two-pronged—to protect the interiors of the building from the harsh weather elements and also to accentuate aesthetics.
Cladding can be made from basic to advanced lightweight materials, including light alloys, polymers, cement blends, recycled polystyrene, and fibre-reinforced composites of plant material such as wheat or rice straw fibre (please note, not all are necessarily available in Australia). The issue has been, that some cladding was manufactured in such a way that the core of the cladding was filled with combustible material, which meant once there was a fire in one panel, it had a fuel source upon which to feed.
However, the right cladding on a building aids in a myriad of ways: keeping the structure protected from the elements, acting as a sound insultation reducing temperature variance inside the structure and more.
First developed as a cost-effective, lightweight building material, composite boards were preferred as they allowed for quick installation. With advances in technology and materials in the course of recent years, cladding is currently broadly utilised over a tremendous assortment of structures and buildings.
Inexpensive and economical, it can be moulded and cut effectively to most sizes or measurement with a wide assortment of surface finishes – which suit architectural designs and plans. But as stated above, as design technology improved, not all production methodology did, meaning some were combustible (non-compliant). These panels now plague owners and builders of private residences as well as makers of commercial offices and factories.

 

Review of Past Fire Cases

There has been a long history of fire cases involving some prominent structures and buildings utilising highly-combustible external cladding. We are referring to Dubai, China, and the United Kingdom, but Australia too has likewise encountered its share of fire cases involving combustible external composite panels extending numerous years back.
 

Lacrosse Building Fire, Australia, 2014

On 24 November 2014, the Lacrosse Building; a 23-story high rise in Melbourne, Australia caught fire. There was no fireproof external wall cladding and the aluminium cladding was believed to have been one of the fuels that exacerbated the fire sending shockwaves through the nation's development industry. It also acted as the catalyst for ongoing investigations into  all aluminium cladding with a polyethylene centre which has been utilised for over forty years on a huge number of structures. Fortunately, no casualties or serious injuries occurred during this incident.

 

Neo200 apartment complex, Spencer Street, 2019

In February, fire ravaged the centre floors of the 41-story Neo200 high-rise building prompting the evacuation of at least 200 inhabitants. Vital to note was that it did not have accredited fire rated external wall cladding, but had a similar kind of cladding as the one used on London's 24 storey ill-fated Grenfell Tower that burnt on 14 June 2017 in North Kensington (London) causing 72 deaths.

 

Impact of external fires on internal fire

From these previous cases, it is important to note that there is a correlation between fires that start externally and how they can impact internal fires.
 
In the Lacrosse Building Fire, a rapid vertical flame spread in the building’s metal composite cladding after starting on the outside divider. It quickly spread vertically up the structure entering into the internal apartments over numerous levels.
 
In addition, the fire also caused the fire alarm warning system to fail on some of the levels leading to some residents being unaware of the hazard. Firefighters were forced to enter every level, alerting the occupants to ensure total evacuation.
 
Similarly, in the case of Neo200 apartment complex, the Council inspection found that the fire affected essential safety measures including the sprinkler system and fire alarms.

 

What can be done to reduce the risk?

In short, there are serious consequences which may result from a cladding fire. Building regulations require that a fire in a tall structure should be able to be contained and restricted to a solitary storey. Once it spreads to multiple floors it totally hampers protection and control measures that make egress routes and firefighting feasible.
Therefore passive fire security is an essential component of building design and planning. It is a significant strategy for forestalling the spread of flames and smoke all through a structure for a predefined regulated time to enable inhabitants to evacuate.
Wall assembly and fire rated cladding are some of the most significant zones of focus for passive fire protection and design. These assemblies must meet required standards and follow the National Construction Code (NCC) to guarantee optimal fire protection and determine their fire performance.
But more than just containment, a well protected building must include passive fire rating for the structural elements (steel or timber). In the case of a fire which starts on the outside of a building via the cladding, it will (as per the examples above) spread internally eventually. Where this occurs on a commercial office building, where there are large design voids and exposed structural elements, it is essential that the right passive fire rating precautions have been implemented.
In short, total passive fire protection requires use of a diverse range fire resistant materials systematically working together to slow the passage of flames, smoke, and poisonous gases.
If you are looking for solutions to improve your building’s passive fire protection system on a previously constructed building and are unsure of where to start or proceed, let’s have a chat. We have the team and experience to help you with your fire rating compliance.

This entry was tagged : "Passive Fire Protection", Tips

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