Time to assess Rotorua buildings for earthquake risk

Rotorua District Council (RDC) is this week writing to the owners of approximately 1300 buildings asking them to obtain structural engineering assessments to determine if their buildings would be at risk in the event of a substantial earthquake hitting Rotorua.

The preliminary list of buildings to be assessed has been compiled by independent engineering consultants using data on council property records, and taking into account factors such as construction type, design, when a building was built and the nature of its use.

RDC Building Services manager Darrell Holder said the fact that the council required a building to have an engineering assessment did not necessarily mean the building would be unsafe in an earthquake. But a professional assessment would provide reasonably conclusive evidence one way or another about whether or not it was earthquake-prone.

"If a structural engineering assessment determines that a building is earthquake-prone, it will need to be strengthened so that occupants and other people in the vicinity can be as safe as possible. The timeframe for that work to be carried out will depend on what risk category a building falls into when it’s confirmed as needing strengthening. But it will be between 5 and 15 years."

Mr Holder said determining whether buildings were earthquake-prone was a central government requirement applying to all towns and cities under the Building Act. He said it had taken on "new significance and urgency" since the devastating Canterbury earthquakes.

"Most of those buildings we’ve identified in Rotorua as needing structural engineering assessments are non-residential. The small number that are residential buildings all have three or more connected household units and are at least two storeys high.

"All buildings on our list were built before 1976 when new standards came into effect requiring buildings to be constructed to higher technical levels.

"We’re very conscious that this programme of work will cause some immediate anxiety to building owners and, in the longer term, potential disruption and substantial cost if a building needs to be upgraded.

"But it is a government requirement, and it’s about ensuring buildings in our district are safe for everyone who uses them. So we’re committed to working as closely as possible with building owners whose properties are ultimately confirmed as being earthquake-prone," said Mr Holder.

The Building Act defines an ‘earthquake-prone building’ as one that has a structural strength of 33% or less than that of a brand new building built to the existing New Building Standards. The Act requires buildings to be above the 33% level as a minimum, but insurers, financiers and even tenants may put higher expectations on building owners.

Rotorua District Council has organised a public seminar aimed primarily at building owners, to discuss potentially earthquake-prone buildings. The seminar will be at the Rotorua Convention Centre at 1pm on 4 December. It will include presentations by structural engineering and local government representatives, and a question and answer session with a multi-sector panel.

Mr Holder said that anyone with an interest in the topic was welcome to attend and should register before 29 November. Registration can be made by email to shared.services@rdc.govt.nz with ‘Earthquake-prone Building Seminar’ in the subject line and names and contact details included. Alternatively people can call the council on 07 351 8119 to register.