Quake strengthening cost a jolt for business owners | Canterbury News | Local News in Canterbury

Owners of earthquake-prone heritage buildings in Christchurch may have to pay at least $169 million for strengthening works from 2012.

Nearly 500 heritage buildings in Christchurch and on Banks Peninsula would be required to be strengthened or demolished within 15 to 30-years under a proposed amendment to the city council's 2006 Earthquake-Prone, Dangerous and Insanitary Buildings Policy.

According to a review of the policy, these 490 buildings are only a fraction of about 7658 buildings in Christchurch that would be likely to collapse in a "moderate earthquake" - the equivalent of an earthquake in reasonable proximity to the city with a magnitude around 6.5 on the Richter scale.

Un-reinforced masonry buildings - such as 295 of the listed or scheduled heritage buildings - are considered particularly earthquake-prone.

Christchurch Heritage Trust chairman Derek Anderson said the scale of the problem was huge, with 150 heritage buildings located within the city's central business district.

"The council has no realistic policy for heritage buildings and they will collapse in an earthquake," he said.

Scientists predicted a 50% chance of a magnitude 7 quake hitting Christchurch in the next 50 years.

"We're well overdue for a big one. It is a real challenge," Mr Anderson said.

"Most of the heritage buildings in Christchurch were built for purposes different to what they are now being used for."

The trust owns the Smiths Bookshop building in Manchester St and is in the process of letting tenders for earthquake strengthening and restoration work.

Mr Anderson said the cost of earthquake strengthening alone was estimated at some $175,000, to which would be added costs for improving access and egress to Building Act standards.

Earthquake strengthening was estimated to cost about $450 a square metre, he said.

Under the amended policy, owners will have 15, 20 or 30 years to demolish or strengthen buildings, depending on the risk of earthquake damage and the importance of the building, to at least 33% of full code levels (FCL).

The structure would then be deemed no longer earthquake-prone under the Building Act.

To protect the heritage fabric of the buildings, the review recommends buildings be strengthened to 67% of the required FCL.

A 2009 report by Holmes Consulting Group suggested that such an upgrade for one-third of the buildings would bring the total cost to $253 million.

City council environmental policy and approvals manager Steve McCarthy said: "If owners of heritage buildings can't strengthen in the timeframes, then (the buildings) could be deemed to be dangerous and action taken under the Building Act.

"However, we will need to exercise some discretion."

There is provision in the policy for owners who have made substantial progress in strengthening to apply for an extension of up to three years.

"The reality is that some heritage buildings will be demolished as a result of needing to be strengthened or simply because it is not economic to upgrade them and you get deterioration over time. The timeframes proposed are quite generous."

The Christchurch Heritage Trust has also been involved in strengthening the Excelsior Hotel building at the corner of Manchester St and High St and the Star-Times building in Cathedral Square.

Said Derek Anderson: "If we hadn't saved the Star-Times building, Warners was going to have to come down," Mr Anderson said.

He said the trust had been lobbying the city council "to come up with a policy and funding" that would allow owners of heritage buildings to strengthen them.

The city council needed to put between $25 million and $35 million into a fund for saving heritage buildings.

Mr Anderson said there needed to be a partnership between the Government, the city council and building owners.

The policy review also recommends the city council should establish a seismic strengthening grant to assist in the upgrading of priority heritage buildings.

The $842,000 a year made available through the city council's Heritage Incentive Fund is always fully allocated, and would not be enough to support the necessary upgrades.

Buildings that may require upgrading include the Odeon Theatre on Tuam St, the Arts Centre - where substantial earthquake strengthening is being looked into - and the Town Hall, which has already had a certain degree of strengthening.

The policy also contains 15-year strengthening timelines for buildings with special post-disaster functions such as hospitals and fire stations, as well as 20-year timelines for buildings which contain crowds - such as churches - or contents of high value to the community.