Around $47,000 could be shaved off the cost of each new place built in factories under Labour's planned KiwiBuild 100,000-house scheme, an opposition spokesman says.
Phil Twyford is addressing the Prefabrication NZ Conference in Auckland this morning and said a new report showed off-site house prefabrication could save thousands per house.
Value Case for Prefab, a 24-page report from Prefab NZ and BRANZ, outlined the case for faster building of better, cheaper new houses.
Around $32,000 could be saved using standard prefabrication techniques, Twyford said, but a further $15,000 could be saved via better procurement methods.
"This shows KiwiBuild-style builds may be able to cut $47,000 off the cost of building a home while building higher quality homes, faster, with reduced waste and safety issues. It also demonstrates there may be wider benefits to the construction industry an economy as a whole," Twyford said.
The 10,000-house-a-year decade-long KiwiBuild is Labour's answer to the housing crisis which Twyford said was condemning an entire new generation to renting their entire lives.
Prefabrication involves building components in factories which the report said allowed a climate-controlled environment, reduced onsite construction, resulted in fewer people onsite, better quality control, increased waste reduction, quality from custom designs and increased automation and speed.
Twyford praised the systems.
"Our Kiwibuild programme is a once-in-a-generation opportunity to lead our housing industry in a new direction, to take advantage of economies of scale and bulk buying that our thousands of individual smaller firms can't do by themselves, to incorporate modern techniques like high quality prefabrication and off site manufacturing, to innovate, bring down costs and increase the quality of our housing stock. This is an opportunity we have to take.
"When industry voices like BRANZ and Prefab NZ say that greater use of prefabrication can knock $47,000 off the price of a home, and build better homes, it is time to listen. We can change the way we build homes here in New Zealand. We can change the way we do business," he told the conference.
The report said prefabricated components came in all shapes and sizes from small components such as pre-nailed wall frames to panels, larger modules (3D volumes) or even complete buildings.
Canterbury "urgently" needs 15,000 houses and Auckland "immediately" needs 15,000, it said. Co-ordinated procurement and production could result in time and cost savings: $25,000 off a standard house just by using prefab methods but a further $15,000 off due to better procurement or materials sourcing. But more can be saved on each house when large-scale housing schemes like KiwiBuild are in action, resulting in a potential cost saving of $32,000 for each place. New Zealand houses are the third-largest in the world, growing from an average 140sq m in the 1940s to an average 208sq m today, it said.
New Zealand's design and construction industry faces a wall of work and New Zealand was "on the brink of the biggest construction boom in 40 years", the report said, citing the 2013 National Construction Pipeline report.
This week Housing Minister Nick Smith and Auckland Mayor Len Brown released the first monitoring report of the Auckland Housing Accord, claiming great progress on plans for 39,000 houses in the city in the next three years via Special Housing Areas.
Grant Porteous of New Zealand's biggest domestic builder, G.J. Gardner Homes, said prefabrication did not always result in faster outcomes and his business could already complete a simple standard three-bedroom house on a flat site in just 12 to 14 weeks. Many components of housing were already prefabricated, he said, including pre-nailed, pre-assembled walls.