A technical report for the Canterbury Earthquakes Royal Commission says all unreinforced masonry buildings in New Zealand should be reinforced, at a cost of around $NZ2 billion ($1.57 billion).

The report by Associate Professor Jason Ingham of the University of Auckland and Professor Michael Griffith of the University of Adelaide notes the cost is more than the $NZ1.5 billion ($1.18 billion) value of 3867 unreinforced masonry buildings in the country.

“A cost-effective strategy is needed to direct the limited resources available to tackle this problem,” they said.

The February earthquake killed 40 people when unreinforced masonry buildings collapsed. The report says such buildings need to be strengthened to protect people from hazards like falling chimneys and parapets.

The royal commission is focusing on building failure, and the report recommends that some structural elements of unreinforced masonry buildings be improved to the standard of new buildings. Other elements should ensure the buildings are upgraded to a minimum 67% of new building standards.

The report also recommends adoption of one national building standard instead of having standards set by local councils.