Cyclone Resilient Construction

cyclones are not as robust as those applied in FNQ duePhoto courtesy of Robyn Jay

As the Gold Coast Oceanway debate reignites, opponents are citing the potential for a cyclone storm surge to severely damage or destroy the 3.5m-5m wide beachfront concrete boardwalk which could then become a dangerous hazard.

With category 2 Cyclone Alfred about to hit our coastline, we’ll find out soon enough whether this is a valid concern or not.

Whilst the impacts of a storm surge and the potential for flooding rains are significant concerns for many residents of our city, cyclonic winds are likely to cause more widespread damage to buildings.

Cyclone Strength

The intensity of a Cyclone is rated numerically from category 1 (lowest) to category 5 (highest), based on the maximum wind gusts experienced. (Understanding typical cyclone categories.)

Queensland is no stranger to extreme weather, particularly cyclones that frequently impact Far North Queensland (FNQ) and, to a lesser extent, Southeast Queensland (SEQ).

Cyclone Risks in FNQ vs SEQ

FNQ experiences cyclones more frequently, with powerful storms such as Cyclone Yasi (2011 – category 5) and Cyclone Larry (2006 – category 4) causing widespread damage. The region faces higher wind speeds, storm surges, and intense rainfall, necessitating robust building codes.

In contrast, SEQ is less frequently affected, but cyclonic winds can still pose a risk as we have experienced during severe storms and ex-tropical cyclones that have tracked south from their typical place of origin in the Coral sea.

Cyclone Glenda – Photo courtesy of Robyn Jay

In the past century SEQ has been impacted by cyclones including:

• The  Great Gold Coast Cyclone (1954 – category 3) : Before names were assigned to Cyclones, this was one of the most severe storms to hit the Gold Coast and Brisbane, causing extensive damage with destructive winds, storm surges, and widespread flooding.
• Cyclone Dinah (1967 – Category 4) : It was regarded as the strongest storm to approach the southern coasts of Queensland since reliable records began. It caused the largest waves being observed in the southern part of Queensland in living memory.
• Cyclone Glenda (1967): Whilst not crossing the coast, it resulted in large waves that eroded Gold Coast beaches and killed 6 people in boating accidents.
• Cyclone Wanda & Zoe (1974 – both category2): Triggered the infamous Brisbane and Gold Coast floods, causing widespread damage.
• Cyclone Nancy (1990): Crossed the Australian coastline at Byron Bay and caused extensive flooding and damage with cyclonic winds that recorded wind gusts of up to 60 – 70 knots.
• Cyclone Oswald (2013): The remains of a category 1 cyclone that made landfall in FNQ, it brought torrential rainfall and destructive winds, leading to severe flooding in SEQ.
• Cyclone Debbie (2017 – category 4): Caused significant wind damage and flooding across SEQ after making landfall in North Queensland.

Cyclone Resilient Construction

Due to differences in cyclone intensity, frequency, and structural vulnerability, building construction methods differ between FNQ and SEQ.

This is based on the anticipated risks in each region.

Building Construction in FNQ: Resisting Severe Cyclones

The following are some of the key construction principles adopted in FNQ to resist the damaging impacts of cyclones on buildings.

1. Stronger Structural Framework:
   • FNQ buildings require reinforced concrete and steel framing to withstand wind speeds exceeding 250 km/h. Timber frames must use cyclone-rated connectors, such as tie-down rods and metal brackets, to prevent roof uplift.
2. Cyclone-Resistant Roofing:
   • Roofs in FNQ are often designed with a steep pitch (around 30 degrees) to reduce wind pressure. Metal roofing sheets are screwed down with cyclone-rated fasteners, and overhanging eaves are minimized to prevent wind uplift.
3. Impact-Resistant Windows and Doors:
   • Windows and doors must be fitted with cyclone shutters, laminated glass, or reinforced roller doors to withstand flying debris and extreme pressure differences.
4. Secure Foundations and Elevated Construction:
   • Coastal areas prone to storm surges require elevated homes on reinforced concrete piers or deep-driven piles. This ensures stability and protection from flooding and storm surge scouring.
5. Cyclone Shelters and Safe Rooms:
   • Some FNQ homes incorporate dedicated cyclone shelters with reinforced walls and ceilings, providing a last-resort safety zone during extreme events.

Building Construction in SEQ: Wind and Storm Resistance

Construction principles adopted in SEQ  to resist the damaging impacts of cyclones are not as robust as those applied in FNQ due as due to the lower risk of impact from a high category Cyclone.

1. Moderate Wind-Resistant Design:
   • SEQ buildings require compliance with Wind Region B standards under the National Construction Code (NCC). While not as extreme as FNQ, homes must still have roof tie-down systems and reinforced connections.
2. Flood-Resilient Foundations:
   • SEQ experiences storm-induced flooding rather than storm surges. Homes in flood-prone areas are built on raised slabs or elevated on stumps to reduce water damage risk.
3. Reinforced Roofing and Cladding:
   • Roof structures are built with bracing systems and anchored to resist strong winds. While not always cyclone-rated, SEQ homes still use metal roof battens and secured sheeting.
4. Storm-Proof Windows and Drainage Systems:
   • Houses feature impact-resistant glazing, but cyclone shutters are not mandatory. Effective stormwater drainage systems help prevent water damage from heavy rainfall.

BOM predicted path of Cyclone Alfred from 7am 5/3/25

Conclusion

Building design in FNQ must withstand Category 5 cyclones, requiring extreme structural reinforcement, whereas SEQ homes focus on moderate wind resilience and flood prevention.

While both regions adhere to stringent building codes, FNQ demands additional cyclone-resistant features to mitigate the risk of more frequent and intense storms.

These construction techniques are mandated for all new construction, however many older buildings on the Gold Coast may not have this level of resistance to the impacts of a cyclone.

Time will tell how much damage Cyclone Alfred inflicts on SEQ.