However, the timeframe for registered heritage buildings can be pushed out by a further 10 years, and low risk and low usage buildings can be exempted.
Schools, hospitals and emergency buildings like fire stations will need to be assessed and upgraded in half the time. Unreinforced masonry facades and parapets in high traffic areas will also need to be strengthened sooner.
A contestable assistance fund has been set up to help private owners of heritage buildings meet strengthening costs.
Today Smith said more assistance could be offered.
"I am also exploring options for Government assistance in multi-unit complexes where some parties may struggle to raise the finance for their share of strengthening costs.
"Officials are considering whether we could extend other Government housing guarantee products schemes to assist in these circumstances."
Smith said earthquakes were New Zealand's biggest natural hazard.
"These new laws involve an uncomfortable and inevitable trade-off between safety and cost but will save hundreds of lives in future quakes when fully implemented."