Australia experiences an average of 13 cyclones each year. When they reach land, these storms can have devastating effects on buildings. Several experts are now calling the country’s building regulations into question.
Each year, Australia experiences about 16% of the world’s cyclones. About half of these storms make landfall. But when they do, they cause widespread damage in communities. We saw the effects of this first-hand when Tropical Cyclone Debbie hit New South Wales and Queensland. The storm led to about $1 billion in damages, and those are only damages that had insurance cover. It is likely that many millions of dollars more uninsured damage also occurred.
The cyclone ripped through the region like few in history. Hamilton Island businessman Kevin Collins spoke of seeing a catamaran embedded in a pylon. Other regions experienced losses in communication as telephone poles took a battering. Houses ended up ruined and widespread flooding affected many communities.
As for the human cost, the cyclone resulted in the loss of 14 lives.
Needless to say, it was a damaging period in Australia’s history with cyclones. And some experts believe that things may get worse. The effects of climate change will have drastic effects. It may increase the risk of cyclones occurring and reaching land.
The storm’s aftermath has led to many calling Australia’s building regulations into question. The possible future increase in tropical storm occurrences has more people worried. Before getting to that, let’s look at what makes cyclones so dangerous.
What is a Tropical Cyclone?
Tropical cyclones and hurricanes are the same thing. Some also refer to them as typhoons.
Think of a cyclone as a giant engine. The storm uses moisture-filled warm air to power itself. This is why they occur with much more regularity in warm regions. The storms usually form over warm ocean waters that are near to the Earth’s equator.
As the warm air above the water rises, it creates an area of low pressure below. This causes air with higher pressure to force its way into the gap. The cycle continues for a while, with the new air heating up and rising. Another gap appears, which leads to more air entering the “engine”.
This warm air cools as it rises, eventually forming clouds. Over time, this cycle of air and clouds begins spinning and growing. That is the starting point of a cyclone.
The rotations get faster and the area of low pressure shifts from underneath the warm air. It moves into the centre of the rotating air, creating an eerily calm eye. The storm rotates around this eye, constantly moving over the ocean as it does so.
Often, these cyclones die out in the ocean before ever reaching land. But they can become stronger in the right conditions. When wind speeds reach about 120km/h, the cyclone becomes a tropical cyclone.
If the tropical cyclone reaches the land, it starts dumping rainwater over every area that it touches. Wind speeds pick up enormously too. In the case of Tropical Cyclone Debbie, they reached a peak of 195km/h.
Reaching land also causes the storm to slow down and lose strength. Still, it may travel over hundreds of miles before it finally dissipates.
It is this combination of high winds and ocean water that causes such devastation to homes. Protection against both is paramount given the regularity of these storms.
The Current Wind Regulations
The current wind loading standard in Australia depends on the region you are in. The 2011 AS/NZS1170.2 standard defines this for builders. For example, the minimum standard in New South Wales is 250km/h.
Generally, this was enough for structures built post-2011 to withstand Tropical Cyclone Debbie. But a University of Queensland study found something disturbing. It discovered that winds in Hamilton Island came very close to reaching this minimum. A stronger cyclone may have had a devastating effect on new structures.
What is also worrying is that there are several recorded instances of winds exceeding this load in Australia. For example, 1996’s Tropical Cyclone Olivia reached a top speed of 408km/h. Surprisingly, that cyclone led to no fatalities. But it shows that current standards may not be good enough. Another cyclone of that power could have even more devastating consequences. Current building regulations may not protect against it.
Still, the University of Queensland’s study found that most modern homes should withstand most cyclones. But modern homes do not account for every property.
The Community Issue
You will find houses of all different types and ages in most communities. Any built before the 1980s may have no protection against high wind speeds at all.
So, for all of the good that 2011’s regulations brought, there’s still an enormous number of homes at risk.
The same study discovered that most of the damage that Tropical Cyclone Debbie caused occurred in older buildings.
In particular, buildings with the following issues are at risk:
- Decline of structural strength over time
- Poor tie-downs between the building’s rafters, trusses, and battens
- Deterioration of the building elements between the roof and walls
The study went on to note that most modern buildings experienced very little damage. However, it pointed out that poorly installed details still present a risk. If a detail does not match the AS/NZS1170.2 standard, it does not matter how modern the building it’s attached to is.
Having said that, the 2011 wind loading standards do appear to have protected modern buildings. But there is something these regulations do not account for – water
The Water Ingress Problem
This is the main point of contention among the experts. Many say that tropical storm protections should include water ingress, as well as structural elements.
The study inspected hundreds of modern buildings over the course of its running time. It found that many of these buildings experienced damage, despite withstanding the cyclone.
Water ingress was the problem.
Even with the current building codes, these buildings still had issues that allowed water to seep in. Ceilings and internal building linings ended up damaged. There was also millions of dollars’ worth of contents damage.
Most worryingly, this occurred in areas that recorded lower-than-peak wind speeds.
What is Water Ingress?
Water ingress is not a phenomenon that is unique to tropical storms. However, water-driven ingress tends to occur during tropical storms.
It is all to do with those fluctuations in wind pressure again. The air pressures in the storm are usually different to those inside a building. As with the formation of a cyclone, the air with the higher pressure forces its way into areas of low pressure. Namely, your home.
This form of water ingress leads to water entering the home in a variety of ways. These include:
- The flashings that usually channel water away from the property
That last one shows just how powerful this surge of high-pressure air can be.
Moreover, the building does not require any structural weaknesses for this to occur. A building that is completely untouched by the wind may still experience water ingress. The same goes for closed and sealed windows and doors.
As a result, many argue that building regulations must now include some sort of protection against ingress. Currently, none exist. Many manufacturers focus primarily on meeting existing standards. They do not design specifically to guard against water ingress. Wind resistance takes priority.
The study concludes that much of the property damage that occurred during the cyclone came as a result of water ingress. It even speculates that the dollar amount attached to this will end up higher than that attached to wind damage.
Why Aren’t There Any Codes for Water Ingress?
The issue comes down to personal safety.
The government considers high winds as a risk to human life. After all, a collapsing structure could crush somebody. This leads to injuries or fatalities.
Water ingress is not viewed in the same light. Despite potentially causing millions of dollars in property damage, it does not present an immediate threat to human life.
Unfortunately, this does not account for the emotional toll. There are plenty of stories of people attempting to sweep water away from their belongings, only to give up.
On top of that, water ingress leads to insurance companies paying out millions of dollars. It can also damage business premises, which has a direct impact on the economy.
Yes, the consequences are more financial in nature. But that does not mean that building codes should disregard it. Building regulations would protect the economy. Furthermore, they would help in the recovery process after the storm.
The Potential Solutions
There are several potential solutions to the water ingress problem.
Solution #1 – Better Building and Wind Loading Standards
This is the most obvious solution. However, it is also the one that takes the most time.
New building standards could dictate how much water certain fixtures can let in. Improvements in design and manufacture could also safeguard against ingress. However, a lack of regulations means that many will not go the extra step required to protect their buildings.
In this case, it may be up to manufacturers and installers to cover the slack.
Manufacturers should focus on improving their products’ Water Penetration Resistance rating. The higher the rating, the more able their fixtures are to guard against water ingress. This is particularly important for door and window manufacturers.
Installers can also help. If they use products with proven water resistance capabilities, they make the homes they build much safer.
Solution #2 – The DIY Method
Without any building standards, many may have to resort to other methods to protect against water ingress.
These may include:
- Using sandbags to prevent water from seeping through small gaps
- Elevating important items off the floor
- Checking the sealants on doors and windows to ensure there aren’t any cracks
- Shutting off the building’s electrical systems
While these solutions may mitigate the damage, they do not directly protect the home.
They are also difficult to execute in the midst of a tropical storm. A lack of preparation time prevents many from taking these measures
The Final Word
The combination of wind and water that comes with a tropical cyclone presents major problems.
Building regulations account for winds of up to 250km/h. But the same does not apply to water ingress. Regulators must consider creating new standards for window, doors, and other fixtures. Otherwise, water ingress will continue to cost people and businesses millions of dollars.
For now, manufacturers and installers must account for the issue themselves. That is where Safetyline Jalousie can help. Our louvre windows have a Water Penetration Resistance of 800pa. This prevents ingress where other windows may fail. If you would like to hear more, contact one of our Business Managers today.
Tropical Cyclone Knowledge Centre – Australian Government Bureau of Meteorology
Australia’s Tropical Cyclones – Australia101.com
Building Codes not enough to protect homes against water damage in severe storms – The University of Queensland