Seismic Construction Within Fit-Out

The importance of seismic building codes and regulations

Unlike New Zealand, which sits atop more than one tectonic plate and is thus prone to more severe earthquakes, Australia rests on top of only one. This means that Australia’s earthquakes are less common and severe than those of its neighbour. However, despite this, minor earthquake damage can and does occur across the country in various places just about every year.

While these seismic events are mostly not severe, they can still cause minor damage and can even result in injuries and death if seismic building codes and regulations are not adhered to.

Earthquakes that measure 3 or more on the Richter scale occur about 100 times a year across Australia, with those measuring at least at a magnitude of 5 taking place every one to two years. Those earthquakes between the magnitude of 3 and 5 are felt but do limited damage to most buildings and infrastructure.

Perth, Sydney, Melbourne and Adelaide are all at moderate risk of seismic events, while Canberra is considered one of the highest-risk cities in the world for earthquakes.

However, earthquakes that measure 5 and up can cause more significant damage and injuries, increasing in severity with each level up to level 8 on the Richter scale, which is considered catastrophic. The most severe earthquake in recorded history measured 9.2 in Alaska in 1964.

Although rare, a level 8.2 earthquake occurred in Newcastle as recently as 1989, causing significant damage to structures, killing 13 and injuring 160 people.

In general, Australia’s most dangerous earthquakes are considered relatively low-probability events but, when they do occur, they are of significant consequence.

Seismic Events And The NCC

Australia’s National Construction Code (NCC) of 2019 stipulates that all buildings must comply with AS 1170.4-2007: Structural Design Actions Part 4: Earthquake Actions in Australia.

The aim of these building regulations is first to protect lives and second to minimise the amount of damage caused by earthquakes to property, infrastructure and the economy.

This regulatory framework essentially requires both structural and non-structural aspects of buildings ‒ such as fit-outs ‒ to account for seismicity in terms of their design, construction and materials used.

The codes divide buildings into four main categories of importance, with most commercial buildings falling into level 2. Schools and other public spaces where more than 300 people can gather in one area are level 3, while hospitals and other critical infrastructure central to disaster recovery are considered level 4. Unless houses are higher than 8.5 m, they are not required to comply with any seismic building codes.

This level of importance, according to the official delineations, is one of the most critical factors in determining what kinds of seismic accommodations a structure should make. Other factors, however, also play a role in determining the degree of compliance to which a building should adhere.

These factors are the type of soil on which the foundations of the structure are built, the location of the building in terms of its geographical position as well as its position in relation to other structures nearby, the architectural design of the building, as well as any furniture, fixtures and equipment, as the seismic risk factor is directly associated with mass.

How Does This Affect Fit-Outs?

While structural components of buildings rated importance levels 2 to 4 in Australia have been required to be able to withstand seismic events for more than 20 years, since the introduction of the 2019 NCC, it is now expected that all non-structural aspects of buildings are also built to such standards as well.

This includes all aspects of fit-outs, including ceilings, wall panelling, lighting fixtures, electrical installations, plumbing, HVAC systems, mechanical plant equipment and any other fixtures. All of these nonstructural components need to be capable of withstanding both vertical and horizontal seismic forces, with the capability built into both their design and their function.

Suspended ceilings are an example of something that an earthquake-proof fit-out might entail, along with suspended services in the ceiling void ‒ such as cabling, light fixtures and even plumbing.

Various creative walling and wall panelling options exist on the market that are not only capable of withstanding seismic events but can also serve to reinforce the structural component of the building as well, from simple wood panelling to novel concepts such as suspended curtain walls. Applying safety film on all glass panes will also help ensure that they will not shatter or explode during an earthquake, which can cause numerous injuries.

In addition to ensuring that all fixtures are earthquake-proof, seismic fit-outs might also consider the use of furniture that can be helpful during seismic events, such as special desks designed to be hidden under that can withstand heavy objects falling on top of them. Such items can save lives in the case of an earthquake of magnitudes above 3 on the Richter scale.

Since the introduction of the 2019 NCC, it is now expected that all non-structural aspects of buildings are also built to such standards as well.

Cost Implications

Many business owners might be concerned about the cost implications of seismic fit-outs that comply with the NCC. However, these kinds of fit-outs need not bear additional costs since just about every commercial building, whether it’s an office or a retail store, requires it. Thus the cost is standard.

Moreover, the potential cost of not bringing one’s commercial building up to code could be far greater. Not only will the damage be far worse and far more expensive to fix should an earthquake of sufficient magnitude occur, but one could also be on the receiving end of penalties and fines for noncompliance.