In February 2011, New Zealand experienced shock and devastation as the Canterbury earthquake measuring 6.3 on the Richter scale killed 185 people – 115 of whom were in the CTV building which collapsed.
That no doubt turned to anger the following year after a Royal Commission found that the building should never have been given consent in 1986 because its design did not conform to building standards which were applicable at the time.
Following those earthquakes, new legislation which will come into force on 1 July will alter the way in which risk associated with earthquake-prone buildings is managed around the country.
Achieved via the Building (Earthquake-prone Buildings) Amendment Act 2016, the new rules divide the country into areas of high, medium and low seismic risk. In the case of most buildings, authorities will be required to undertake investigations and identify earthquake-prone buildings within five, ten or fifteen years according to whether or not they are in a high, medium or low risk area. After this, owners whose buildings are deemed to be potentially earthquake prone will be given twelve months in which to provide an engineering assessment of the building. Where buildings are in fact determined to be earthquake prone, owners will have either fifteen, twenty-five or thirty-five years according to whether they are situated in high, medium or low risk zones respectively in which to either demolish these buildings or alternatively strengthen them to the extent that they are no longer considered to be earthquake-prone.
Special timeframes will apply to be ‘priority buildings’, which will need to be identified and either demolished or remediated within half of the time that applies to other earthquake-prone buildings. These include schools, emergency service facilities, hospitals and ‘corridor buildings’ which would block major roads and impede important emergency service routes were they to collapse. An earthquake-prone hospital in Wellington (high-risk zone), for example, would have to be assessed within two-and-a-half years and remediated within seven-and-a-half years – not five and fifteen years as would apply to most other building types within that city.
Buildings will also need to be remediated sooner whereby the owners undertake a ‘substantial alterations’ – additions or alterations with a value which is equivalent to or greater than 25 percent of the overall value or RV of the building. Where this happens, it will be a requirement of any consents which are granted that earthquake-prone buildings be strengthened at the same time as the alteration work is taking place.
Most residential buildings are excluded as are farm buildings, stand-alone retaining walls, fences, monuments that cannot be entered (such as statues), wharves, bridges, tunnels and storage tanks.
In terms of defining earthquake prone buildings, it should be noted that the new legislation adopts a similar threshold to that which was previously in place in that a building is considered to be earthquake prone where (a) it would have its ultimate capacity exceeded in a moderate earthquake and that (b) any collapse of the building would be likely to cause injury, death or damage to other property. In practice, this is generally considered to be a building which meets less than 33 percent of the new building standard.
Dominic Lundon, a property and construction lawyer and partner at New Zealand law firm Buddle Findlay, said the new laws are geared towards driving a more consistent approach toward the management of earthquake-prone building risk throughout the country. Currently, he says existing management in this area is determined largely by local authorities – a situation he says has led to varying approaches across jurisdictions.
“At the moment, the local authorities administer the Building Act through building consents,” Lundon said. “And although there is a Building Code, they all have different views about how they are going to deal with all of the measures they are going to take in respect to it. That’s flowed through into how they’ve manage earthquake prone buildings in the wake of Christchurch and other earthquakes.”
“One of the main aims of this legislation is to help standardise things across the country. It will become less about local authorities and more about particular geographic areas.”
Lundon says the amendments have also enabled the classification of being earthquake prone to be applied to part of a building as opposed to the entire structure. This avoids the situation whereby properties owned by different people in a block of flats, for example, are all deemed to be earthquake-prone by virtue of one end wall consisting on unreinforced masonry.
In terms of what engineers should do, Lundon says it is important to make themselves aware that the regime has changed and that tighter timeframes compared with the previous situation for assessment and action now apply as determined by the risk profile of the area concerned. They will also need to understand the processes and methodology which particular authorities will adopt for assessing and identifying earthquake prone buildings at a localised level. After that, they will be able to advise building owners about the type of assessment which will be required on their buildings. Reporting processes, as well, will need to be tailored according to the parameters set by local authorities.
Greg Wise, a property and real-estate lawyer and partner at law firm Chapman Tripp, says it is important for engineers to familiarise themselves with the new zones as well as the types of building which qualify as a ‘priority building’ and how these impact the timeframes required for assessment and subsequent strengthening or demolition. For property owners, Wise says it is useful to be aware of the trigger for strengthening work associated with substantial alterations and how these may ‘bring forward’ the need for (and cost of) remedial work. In addition, it would also be useful for engineers to make themselves aware about the circumstances in which the new law enables assessments which have previously been undertaken and notices which have previously being issued to be used in place of new assessments being required (the law enables this provided that certain conditions are met).
Finally, Wise says the profession should seek cohesion around exactly what it means to be confident about the expected behaviour of the building following the initial seismic assessment which must be undertaken. That matters because the new law requires detailed seismic assessments to be undertaken if an engineer is not confident about the building’s expected performance after an initial seismic assessment. At the moment, he says exactly what the criteria will be for an engineer to be confident in this area remains unclear.
Peter Smith, President of the New Zealand Society for Earthquake Engineering and consultant for Spencer Holmes, says the new laws will not substantially change what engineers do from a technical standpoint but will instead see the profession working according to new timeframes which will be set on a nationally consistent basis and will vary according to both the seismic risk associated with the area concerned and the type of building in question.
Smith says one of the biggest challenges relates not so much around technical matters but more around stakeholder engagement. This is especially with regard to a building which extends across multiple titles and therefore involves multiple owners. Where this happens, he says there could be significant effort involved in obtaining agreement from the relevant parties about the exact nature of the work which should be done, who should meet the cost and when this needs to be performed.
In addition, he encourages owners in the higher seismic zones to adopt a proactive approach bearing in mind that timeframes are now shorter and the need to ensure adequate engineering and other resources were available for the works to be completed in good time.
Finally, Lundon says some of the more proactive engineering firms might be able to realise an additional opportunity to position themselves as advisors to councils about appropriate methodologies for assessing buildings and identifying which ones are and are not earthquake-prone.
“If there are any engineers out there who are reasonably proactive and get to grips with this relatively quickly, there are opportunities for them to advise council about the methodology which might be appropriate,” he says.
“As well as developing products for owners, they could be developing products for councils as well.”