City buildings may require bolstering

00:32, Dec 08 2012

A "significant proportion" of Timaru's central city commercial buildings will require strengthening work if proposals being considered for the new national earthquake-prone buildings system become law.

It is estimated there are between 15,000 and 25,000 earthquake prone buildings in New Zealand, under the current policy and regulations, equating to 8-13 per cent of all non-residential and multi-unit, multi-storey, residential buildings.

The number of buildings on the Timaru District Council's earthquake-prone buildings register was unavailable yesterday, but back in May last year there were 23, of which 19 had been upgraded to at least the minimum seismic requirements.

Proposals put out for public comment by Minister of Building and Housing Maurice Williamson yesterday call for all such buildings to undergo seismic surveys within five years of such a policy change.

Timaru consulting civil engineer Bob Hall suggested a "significant proportion" of inner Timaru commercial buildings - most of those that were pre-1970 - would require work to bring them up to the suggested 33 per cent of the current structural requirements for new buildings.

The major problem was that the front portion of the older buildings were two storey with a parapet, with a single storey behind. The most vulnerable part of the building was the front ground floor area due to the weight from above, on an unreinforced building.


Those built from 1970 onwards should be pretty close to reaching the modern code, he said.

He suspected more than half the buildings would require work, it would also depend on how well the building had been looked after.

His own office was in the Public Trust Building, built around 1922, which was almost identical to one of the few buildings that survived the 1931 Napier earthquake.

The minister's proposals suggest all earthquake-prone buildings need to be strengthened, or demolished, within 15 years of the changes taking effect rather than the present average time of 28 years.

It is proposed the current national earthquake-prone building threshold of one-third of the requirement for new buildings not be changed.

Mr Williamson said the consultation document contains proposals from the year-long review of the earthquake-prone building policy system by officials and a team of experts. It also responds to recommendations made in Volume 4 of the Canterbury Earthquakes Royal Commission report.

Consultation ends on March 8.

The Timaru Herald