Protecting structures from floodwater
Authors: Matthew Mason, Emma Phillips, Tetsuya Okada & James O’Brien
This factsheet summarises the key findings from a project that analysed the damage to buildings in Queensland and Victoria following the 2010-11 eastern Australia floods. In the worst affected state, Queensland, 58 600 insurance claims accounted for $2.4 billion in insured losses. Many of these costs were due to inadequacies in Australian residential building practices which left houses vulnerable to damage and possible structural failure when exposed to floodwaters. By identifying a buildings specific vulnerabilities to different flood impacts, appropriate measures can be taken to reduce the future likelihood of their occurrence. This factsheet provides information on the different pressure forces and sources of damage affecting buildings during floods, and on addressing flood risk to new and existing structures. Nine recommendations are made to improve building resilience to floods. These are: 1) continue to develop accurate flood maps, 2) consider introducing independent flood assessment bodies, 3) expand proposed flood resistant design requirements in the Building Code of Australia (BCA), 4) set minimum freeboard restriction of at least 300 mm, 5) include storm surge and coastal wave areas in the BCA, 6) require buildings being repaired or raised due to flood events to apply flood resistant design methods, 7) promote cost-benefit analysis of retrofit methods, 8) update and maintain prescriptive technical design manual, and 9) allow for multiple flood levels in design and construction.