All earthquake-prone buildings should be strengthened or demolished within 15 years of assessment, the New Zealand Government says in an initial response to the Canterbury Earthquakes Royal Commission.

Non-residential buildings and multi-storey, multi-unit residences should be assessed for quake risk within five years and the information made public, it suggests in a consultation paper following the royal commission and a two-year review of building standards.

There are 15,000-25,000 earthquake-prone buildings, comprising about 8-13% of all non-residential and multi-storey, multi-unit residential properties, according to Building and Construction Minister Maurice Williamson.

The royal commission was told it will cost more to repair unreinforced masonry buildings than they are worth, and Mr Williamson says there must be a balance between protecting people and managing the economic implications of strengthening or demolishing properties.

Volume four of the royal commission’s report was released last week. Volumes five to seven will be released before Christmas and the Government expects to issue its response early to mid-next year.

Unreinforced masonry buildings caused 39 deaths in the quake of February 22 last year.

Volume four’s recommendations include a building grading system that the public can understand and the removal or securing of hazards such as chimneys, parapets and ornaments.

It says external walls should be retrofitted on unreinforced masonry properties and legislation should provide for a duty of disclosure if a building is potentially dangerous.

Consultation on the government paper will run until March 8.