New MBIE guidelines put Wellington buildings under fresh seismic microscope

A full seismic assessment rating process for Bowen House is now underway. Photo / Getty Images

Wellington City Council is working to identify buildings that may pose similar seismic concerns as the central library and Bowen House.

The library was closed a day after WCC received an engineering report highlighting structural vulnerabilities to do with the width of the building's floor seatings.

Meanwhile, Bowen House is undergoing a full seismic assessment. This follows an initial report into one of its floors, based on data from 2013.

Both buildings are under the scrutiny of new guidelines being proposed by MBIE after two floors of Statistics House partially collapsed in the Kaikoura Earthquake.

MBIE's guidelines around precast concrete floor systems are a technical proposal to revise Engineering Assessment Guidelines for seismic assessments.

They are not yet part of legislation and cannot be used to determine whether a building is earthquake prone.

At this stage government agencies are satisfied staff can remain in Bowen House. If at any point throughout the assessment process they receive evidence the building is not at an acceptable standard, immediate action will be taken.

The 22-storey office building houses members of Parliament and parliamentary support staff.

It's important to note the library was closed under a unique set of circumstances with more than 3000 people visiting it daily and its complex design, which includes large voids and an irregular shape.

But its abrupt closure and the uncertainty around Bowen House still raises questions about the future of other buildings around the city, if these guidelines do become mandatory after MBIE does its homework.

"MBIE requires evidence before it considers a change to the Engineering Assessment Guidelines. Engineering New Zealand is gathering evidence of the impacts of the technical proposal on building assessments, in order for MBIE to decide its regulatory appropriateness.

"Wellington City Council, as a responsible and vigilant building occupier conscious of the evolving engineering environment, chose to use revised technical provisions to carry out an additional assessment of the Wellington City Library", MBIE building performance and engineering manager Dave Robson said.

The guidelines are the best advice available at this point in time, WCC chief resilience officer Mike Mendonça said.

Council does not have any specific powers around the issue. However, officers are making their way through property files to identify buildings which could be affected by the "trial" guidelines, Mendonça said.

"We're trying to determine the extent of the issue in Wellington around precast concrete panels and how widespread the problem might be."

While the guidelines were not mandatory, it was pretty difficult for a decision maker to ignore a compelling engineering report, Mendonça said.

'We had no legal obligation to close the library but based on the risks that we perceived, we really felt we had no choice."