Fletcher building have opened Clever Core, a purpose-built offsite prefab house manufacturing facility. Video / Michael Craig

Fletcher Building has today opened its long-awaited giant new high-tech pre-fabricated house-building factory, aiming to cut a 22-week lead time down to six weeks.

"Fletcher Building today announced that Clever Core, New Zealand's largest purpose-designed, offsite home manufacturing facility, is now up-and-running," the company said.

Whether any of the pre-built houses will go to Fletcher's controversial Māngere site at Ihumātao is unknown. For nearly three years, protesters from Save Our Unique Landscape have been campaigning to stop the project to build around 480 houses.

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The Clever Core NZ plant is a 5000sq m or half-hectare warehouse Fletcher has leased from NZX listed Property For Industry on Cavendish Dr at Wiri. Prefabrication of a house can be done in one day, transport to a site on a second day and it could take only about six weeks to do all the finishing, guests learned on a tour.

Fletcher said its new factory would attempt to accelerate house-building by producing core structural components in as little as a day.

"Manufactured wall, floor and roof components, which contain locally sourced insulation, double-glazed windows and allowances for wiring and plumbing, are then transferred to build sites and constructed into the weathertight core of a house by specially trained builders," the company said.

"This reduces onsite build times by 60 per cent, or from 22 weeks to around six to 10 weeks."

Ross Taylor, Fletcher chief executive, said the factory was a $15m investment and a significant advancement in housing development capability.

"Our Clever Core facility will produce core components for at least 500 new homes each year, including 100 by the end of this calendar year. It uses design for manufacture and assembly principles to streamline the design, consenting and manufacturing process," Taylor said.

That aims to speed up build times, give quality control and reduce building waste by up 80 per cent a home.

"Clever Core will initially support our Fletcher Living developments, but we plan to extend the offering to group home builders and retirement home operators in the future. Once production is at scale, we believe Clever Core will play a pivotal role in helping the industry deliver more quality, healthy homes that Kiwis love, faster," Taylor said.

Up to 35 people have been employed including technicians, engineers and carpenters. Some arrived via a scheme to get young, first-time job-seekers into work and training.

Specialist training will be provided for Clever Core employees in collaboration with industry training organisations, Fletcher said.

Fletcher Living plans to use the Clever Core products in its many Auckland housing developments and the first order of 100 homes is due to be delivered by the end of the year.

Projects at Ormiston, Swanson and Beachlands will get the items first.

In 2017, Fletcher unveiled its two-houses-in-four-days demonstration at Hobsonville Point and now builds more than 1000 new residential homes, terraced places and apartments annually.

It has projects at Beachlands, Hobsonville Point, Karaka, Kowhai Ridge, Ormiston, Red Beach, Stonefields, Swanson, Three Kings, Totara Heights, Waiata Shores in Manukau, Whenuapai and Christchurch.

In 2017, it showed fast construction techniques via a time-lapse video of Fletcher Living putting up a new Auckland residential duplex worth nearly $2 million in four days.

The company said it had also built a single Auckland house in a day.

"This was the speed test," a Fletcher Living spokeswoman said of the duplex home construction, built during April just before Easter. The 177sq m four-bedroom homes at Hobsonville Point sold for $935,000 each.

Evans said last year that Auckland houses usually took six to nine months to build.

One day was Fletcher Living's aim but building such a substantial duplex in four days was a significant achievement, he said.

The business was particularly keen to work with the Government on the 100,000-residence affordable KiwiBuild scheme, Evans has previously indicated.