Construction Codes Must Address Building Resilience 1

Monday, March 7th, 2016
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Building Resilience
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Fiji suffers from catastrophic cyclone damage. Tsunami casts a wrecking ball through the Indian and Pacific oceans. Earthquakes in China, and New Zealand leave a swathe of destruction which will take decades to repair.

After World War II, German and Japanese cities as well as those of other European countries and throughout Asia lay in waste. Tokyo, whilst untouched by the new weapons of the atomic age, had been carpet bombed leaving hundreds of thousands without adequate shelter. History has shown that much of London was destroyed in “The Fire” in 1666, and San Francisco had to be rebuilt after a devastating earthquake and subsequent fire in 1906, the damage made much worse as one of the predominant building materials was timber.

In Australia, we saw Darwin flattened on Christmas Eve and Christmas Day, 1974. Australia has endured no fewer than 17 cyclones since 1899. In the past decade, Australia has had an increasing incidence of devastating bush fires.

The damage to Fiji by cyclone Winston is difficult to comprehend. It is hard to conceive of an incident that would be capable of demolishing over 40 per cent of dwellings and damaging most infrastructure and commercial buildings. Should Fiji adopt Australian and New Zealand building codes and standards to improve the resilience of their housing and building stock? The extent of damage would suggest that replacement housing and repairs should be undertaken to a higher standard, especially considering that climate change is likely to see ocean temperatures increase. As a result of this, the energy stored and released in a cyclone or hurricane event will be much higher, and their frequency will also increase.

The cost to the Fijian economy to rebuild housing and infrastructure has been estimated at over $AU600 million, where the GDP per capita is $AU6,044.

The productive capacity of the Fijian economy will be impacted for some time.

Building codes for Northern Australia were upgraded dramatically after the Darwin cyclone. Improved wind bracing and tie downs and an increase in the number of roof fixings were among the measures taken. Contemporaneously, some in the building industry complained that this would increase the cost of building. The counter to this argument is that the risk for insurance companies has made improving the resilience of our housing stock to tempest, flood and fire a major issue, with many people finding building and contents insurance premiums increasing four fold after  natural disasters such as Cyclone Yasi.

One flaw with these improvements to the building codes and standards did not adequately consider the “ballistic” impact of flying debris from other structures that may disintegrate during high winds. In the Bahamas where similar high winds are common, a traditional architectural response has been to include storm shutters to all windows and large door openings.

If life safety is to be a priority for survival in a catastrophic natural event, then storm-proof, fireproof, and ballistic-proof shelters could be considered. Public buildings and community halls should also be built to a higher resistance to fire, cyclone, ballistic and earthquake resistance. There must be enough high quality emergency shelter to ensure the local inhabitants can take shelter for 48 hours or more. The shelter must have independent back-up potable water supply, power and communications. Communications backup has been a profound issue in Fiji after the tsunamis that destroyed coastal areas. Without access to communications, an assessment of damage and emergency needs is impossible and the delay can be life critical.

After the Darwin cyclone, it was apparent that the concrete block laundry, toilet, and store areas on the ground floor of some two-storey dwellings was the only structure which remained intact, and this area was a refuge for many families to escape the tempest.

Is it time that all coastal dwellings and areas prone to bushfire danger have included a fireproof, ballistic-proof refuge which would be fitted with a potable water storage and emergency supplies? It would be an area the size of a small store room, laundry and toilet – I would suggest 20 square metres – for all dwellings up to three bedrooms, and a larger area for homes with more habitable rooms. The refuge would include fire doors, fire separation and inviolate ventilation.

The cheapest and least invasive improvement to current wind resistance measures for housing in Australia is with the number and location of roof fixings. As the intensity of storms increases, the wind strength and the reach of cyclones will be further south. Roofs fail and peel off from the gutter and edge, and once compromised, the entire roof is likely to fail in high wind. This means that on the east coast, cyclones may well travel further south than Yamba in NSW.

Australia has also seen more destructive storm events throughout Australia, such as the recent storms in Sydney which were subject of large insurance claims. Many roof fixings can be retrofitted, and this should be undertaken throughout Australia, perhaps as an insurance initiative to reduce claims. Communities where affordable building and contents insurance are unavailable wither and die as finance houses restrict access to finance, and commercial activity becomes unviable.

The use of sarking under tiles and corrugated tin roofs and around eaves has been shown to often be the difference between catastrophic fire and resilience to bush fire. Storm and fire shutters may also reduce the likely-hood of residential buildings becoming victim to bushfires.

I believe little has been done to improve our housing stock in terms of resilience to high winds, bush fires, earthquake and tempest. The cost benefit of undertaking retrofitting to improve resilience indicates that the relatively low cost would pay huge dividends in terms of reduced insurance claims, reduced damage in catastrophic events, and improved life safety.

Firstly, additional fixings for all roofs on the east coast from Yamba in NSW North, and within 300 kilometres of the coast should be mandatory. Buildings in bush fire prone areas should be retrofitted with sarking under roof tiles and sheeting, and to all eaves. The sarking should be fitted to reduce amber and ash ingress. Fire and storm shutter fitted houses, even where these are stored and applied after weather warning should be encouraged in existing dwellings, and become mandatory for new dwellings.

All new dwellings should have catastrophe-proof shelters. All public buildings and meeting halls should have “bomb-proof,” fireproof and cyclone-proof shelters which can house most people in the community in a severe event. All public shelters should have inviolate communications, radio and backup power. All communities should be required to provide enough shelter for all citizens in the event of a catastrophic event.

Whilst some professionals in the construction industry may see these measures as overkill, I believe they shall be driven by insurance premiums, and insurance companies who have found their current business model unsustainable. The frequency of vast bush fires, cyclones, storms and tempest, seismic activity and other natural events will drive improvements in the robustness and resistance of buildings to severe events.

As New Zealand contemplates a decade-long rebuild of Christchurch, and few buildings are unaffected by cyclone damage in Fiji, it is imperative that these risks be mitigated through these improvements in resilient construction.

Australia has some excellent research establishments to determine the efficacy of building materials. Among these is Queensland University’s Building Engineering facility, which can test most construction assemblies and materials for the performance of these under duress. The CSIRO have a long established reputation in material and assembly testing.

If those responsible for amending building codes and standards do not act quickly to improve building  resilience, these measures are likely to be driven by insurance companies who are beginning to withdraw from areas they perceive as “high risk,” or only provide insurance at a prohibitive cost. Many regional communities are now threatened with declining economic activity due to the hike in premiums, the communities affected by Cyclone Yasi being a case in point.

Looking around many areas on the fringes of urban centres in Australia, one can project that unless additional measures are in place damage during severe climate events such as drought, floods, strong winds and cyclones, the current  projectory of massive insurance losses due to building damage  is only likely to increase. The Australian economy can not sustain the massive destruction in building stock and infrastructure, and as with Fijian authorities responding to the realities of a higher risk environment has become an imperative.

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  1. Ian Bland

    As a long time fire officer and housing carpenter I agree with Grant in this article, I feel we should take it a little further, By increasing the standard residential door size to 890 mm we make the home wheel chair friendly, if at the same time we line the bath room and laundry with 12 mm sheet ply before gyprock sheeting we increase this area to significant strength. Some independent ceiling joist over this area with the same 12 mm ply and some tie down rods and we have created a storm shelter and can now put assistance hand rails anywhere in these area. Accomplishing two for the price of one, improved survival effect and a prepared home for aged living.