Flax-and-earth houses enter testing stage

By SIMON COLLINS

Maori engineers are going back to the land in a $1 million project to build earth houses with flax reinforcing.

The project could let whanau and hapu groups build houses more cheaply than present timber construction methods, using earth and flax from their own land.

The initial research, which includes building earth and timber houses to the same floor plan for comparison, will be funded by $1.1 million over the next five years from the Foundation for Research, Science and Technology's built environment fund.

Project leader Kepa Morgan, 40-year-old associate dean (Maori) of the Auckland University engineering school, had already built two flax-reinforced earth walls in 1996-98, while heading Te Runanga o Ngati Pikiao, a tribal group near Rotorua.

"We had a papakainga [tribal housing] unit," he said. "We had exhausted the cost-efficiencies of timber construction and wanted to look for alternative approaches.

"So we looked at earth. We knew it had problems with ductility [toughness], so we came up with fibre reinforcement with flax."

The group worked out the best kind of soil to use, the best length of flax and the proportions of flax and earth. When the two walls were tested, the Machines - not the walls - failed.

For the next phase, Mr Morgan has teamed with Unitec architecture lecturer Rau Hoskins and two other engineering academics at Auckland University, Manu and Arahia Burkhardt Macrae.

They plan to build one earth and one timber house, plus earth garages and laundries.

"With timber we are looking at a 50-year time frame," Mr Morgan said.

"If we go to an earth structure, that's going to have a time frame of 200 years or more, and in that context it's more appropriate to the inalienable Maori land tenure.

"We are looking for cost advantages over timber and a better quality of environment inside the house - to try and get a more consistent temperature and better control of humidity, which is important for asthma and other things. Timber doesn't have the mass to hold the heat."

Although pre-European Maori did not build earth houses, Mr Morgan said Maori in the South Island were known to sleep on river rocks because the rocks absorbed heat during the day and radiated it out at night.

He said flax was "compatible" with earth, whereas reinforcing it with steel or fibreglass tended to develop failures.

Mr Hoskins said the flax would be cut into 8cm lengths and mixed into the earth flat on a surface. It would then be compacted into a mould and raised to form a wall, like a concrete slab wall.

Mr Morgan said the earth walls and floor of a 100sq m house would weigh about 25 tonnes.

This, plus Maori collective land ownership, would make conventional bank finance difficult, and the project would also explore financial alternatives such as co-housing, where a community built and financed houses jointly.

Mr Hoskins, 38, has designed marae housing for Housing NZ and is about to start on a project for the company in Gisborne to build a six-bedroom house and an adjoining smaller house for an extended whanau group.

He has also built a traditional whare out of raupo swamp reeds on his family's land at Whangaruru Harbour near Whangarei.

"Let's look at where we have come from in housing technique, which was valid up to the 1950s and is somehow totally 'invalid' today," he said.

"We are saying that, while you want to look forward to designing and managing your own housing solutions, you really have to know where you have come from and look at the techniques that are still known to some of the older people, and look from there to hybrid systems that are informed by traditional living patterns.

"If we start from the position of housing solutions dictated by others then we are never going to take control of our own lives."