Investigations of damage to buildings and analysis of insurance claims data following storms have shown that there are still problems with the performance of contemporary engineered buildings. Our buildings are being damaged to non-functional levels during storms not by fastest wind-speed but combinations of wind, rain, hail, etc. Investigating levels and types of damage provides critical information for understanding building performance [1].

Water damage is a significant cause of loss. Many homes and buildings do not suffer major structural damage but still incur heavy losses, driven largely by serious internal water damage.

To highlight these issues, claims data following the severe Townsville flood is analysed.  Approximately 50% of claims have some form of damage resulting from rain entering the building envelope (most common is damage/collapse of ceilings). Many properties have damage from both the rain as well as the rising flood water, but many have only damage by the rain. The Bureau of Meteorology recorded 1260 mm for the ten days of the event (highest on record). However, building design utilises rain fall rates (e.g. mm/hr) for design of drainage paths (e.g. length of time it takes to get volume of rain off the building). The BOM recorded rain rates less than half of the design criteria specified in the National Construction Code.  There are questions on reliability of instrumentation during intense rain such that the gauges may under-read. However, from limited property surveys poor design/construction of roof cladding/slope, flashings, box gutters etc were observed.

To reduce drivers of loss and improve resilience of community we (building industry, regulators, residents, insurance) need effective design criteria to build places to live and work in, that can resist (or accommodate) combinations of “severe” weather. Building codes need a much better understanding (and way of representing) coincident impacts.