Quakes a timely reminder for building owners

Repairs get under way in Wellington yesterday after Sunday's tremors. Building Act changes could require some properties to be seismically assessed within five years and upgraded within 10. Photo / Mark Mitchell

Ministers preparing to discuss law changes requiring upgrading of at-risk structures.

Wellington's earthquakes have put the spotlight back on seismic issues, just as the Cabinet prepares to decide how far to go with a multibillion-dollar push to have about 193,000 earthquake-prone buildings assessed and possibly upgraded.

On Wednesday next week, the economic growth and infrastructure committee is due to consider Building Act changes requiring all non-residential and multi-unit, multi-storey residential buildings to be seismically assessed within five years and upgraded within 10 years. New Zealand has about 193,000 buildings in that category.

Building and Construction Minister Maurice Williamson fronted the national campaign earlier this year to discuss changes after the Canterbury earthquakes royal commission report urged action.

A spokesman from the minister's office said yesterday more than 500 submissions were received and more than 1000 people attended various meetings on proposals for earthquake-prone buildings, defined as below 33 per cent of the standard required of a new building, and those built before 1976. Buildings with unreinforced masonry are also classed as at risk.

Many submitters complained about the 15-year time frame, saying they needed longer while others fretted about the fate of heritage structures.

It is expected that 15,000 to 25,000 buildings will need to be assessed, then strengthened or demolished within 15 years of amendments to the Building Act taking effect.

The Property Council has raised fears of landlords abandoning buildings.

Council chief executive Connal Townsend expressed concern about where the labour would come from to rebuild Christchurch, respond to Auckland's desperate housing demand and upgrade old buildings.

Ian Cassels, a director and shareholder of The Wellington Company and the Property Council's Wellington president, said much of the capital's building stock was robust.

Seismic measures

New buildings could have:

* Lead rubber bearings
* Stiffer, stronger structures
* Energy-absorbing ductile beam hinges
* Exposed seismic construction elements
* Older buildings could have:
* Steel or concrete frames to restrain masonry
* More timber or lightweight steel frames
* Unreinforced elements tied or braced back
Source: Institution of Professional Engineers NZ.