Cave Creek is a name etched in the collective memory of New Zealanders. The tragedy that claimed the lives of 14 people stands as a grim lesson on construction standards. Had the observation platform carrying a group of happy young students been properly built, it would not have collapsed and carried many of them to their deaths. The outcome of the disaster was a resolve to improve construction standards and supervision.
From time to time, disaster strikes on a smaller scale when residential decks or balconies collapse, injuring those unfortunate to be standing on them when they give way. The cause might be poor construction or the deterioration of supports as the dwellings get older. Thankfully we have been spared catastrophe on the scale that struck Jerusalem on Friday.
Amateur video captured the moment - and it was over in a second or two - when the floor on which 300 wedding guests were celebrating gave way in the Versailles banqueting hall. At least 23 people plunged three floors to their deaths; many more were injured. In a country steeled against suicide bombers and the consequences of Middle East conflict, the building collapse shocked the nation.
The cause seems quite conclusively to lie in "an engineering fault" and the builders of the 15-year-old structure are facing hard questions from authorities.
Either poor design, inadequate construction or a combination of the two appears to have led to the failure. The banquet hall was apparently built using a cheap, lightweight construction method common in the 1980s but now regarded as being below acceptable building standards. The method, which used metal plates and thinner layers of cement than standard ceilings, was barred in 1996. Now the Standards Institution of Israel has also warned that other buildings are in danger of collapse.
Multistorey buildings in New Zealand have long been subject to rigorous building standards. Perhaps, in a perverse sort of way, we are fortunate to be in a known earthquake zone. That knowledge has led to construction standards and building approval processes that are designed to be rock-solid. The Building Act and the Building Code are designed to ensure that structures stay standing and their occupants remain safe.
With the Resource Management Act, which applies its own form of scrutiny to the building process, the Building Act and the code provide territorial local authorities with sufficient power to achieve those aims.
But concerns expressed by the Building Research Association about the performance of untreated, kiln-dried framing and poor cladding suggest there is no room for complacency - particularly in the residential building sector. Some homes reportedly have begun to rot within months of being built.
Predictably, timber merchants say there is nothing wrong with the kiln-dried product, use of which has been permitted since a change to building standards in 1996. They blame sub-standard cladding that allows moisture to reach the wood. The standard assumes the environment will be dry.
That suggests the material could be subject to a single point of failure - a breach in the moisture barrier - and that is unacceptable. If building standards and construction methods do not guarantee a dry wall cavity, the untreated timber standard will have to be revised. At the very least, additional requirements should be placed on the use of cladding that does not have inherent waterproof qualities when used in conjunction with the timber.
Building safety is too important to be compromised in the interest of cheaper construction methods. True, the untreated timber problem is more likely to manifest itself as a gradually emerging flaw in the construction of a house rather than in life-threatening catastrophic failure as occurred in Jerusalem. Nevertheless, any structure that has had its integrity weakened must represent a potential source of danger.
We have built up a commendable regulatory infrastructure and building record in our construction industry. Let's keep it that way.
<i>Editorial:</i> Let's be sure our buildings are safe
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