Owner David Mulholland and friends have spent the past seven weeks bringing an unusual rural Whanganui house up to its full potential before putting it on the market.
The Matātara Cob House is on a metal road near Lismore Forest and runs on electricity supplied by 15 solar panels and stored in a bank of 14 batteries. The walls of its lower storey are handmade from clay off the 13ha property.
Most of the property has been placed under the Queen Elizabeth II National Trust (QEII) because it includes an important wetland.
The house was a labour of love for its builders, Clive and Ruth Aim, who laboured from 2007 to 2012. Its five bedrooms and three bathrooms take up 384sq m, and the internal and external walls of its lower storey have an infill of cob.
The mixture is 60 per cent mud from the property and 40 per cent shellrock fines, with a few handfuls of straw for every batch made in a concrete mixer. The material was hand placed and left to dry, then plastered with a mud and sand mixture to smooth the surface.
It dries hard, and the house has 3m eaves on four sides to protect the cob from the weather.
About 80 tonnes of the mixture went into those walls.
Mulholland has given the house "a birthday present" by painting the walls with whitewash - an old-fashioned mixture of hydrated lime, salt and water.
"You put it together, stir and slap it on with a wide brush. It's cheap as chips and very easy," he said.
He bought the house in April 2018, thinking to host friends and volunteers who would help restore the wetland. He's now selling up to live with a new partner in Coromandel, "the best reason in the world to do so".
The house had been fabulous to live in, he said.
"It's the warmest house I've ever lived in by a mile, and cool in summer, and an amazing house to entertain in. I've had lots and lots of visitors staying weekends, and film nights and dinner parties."
Apart from the cob infill, most of the construction is conventional with lots of steel reinforcing in the concrete floor and beams.
"When I was in it during an earthquake, it just seemed to move very gently, all together," he said.
There's a wood burner, and hot water is provided by a wood-fired kitchen stove and gas califonts. There's a diesel generator for back-up electricity, but he's rarely had to use it.
"It's off the grid, but with electric garage doors. It's middle class off the grid."
Rainwater from the large roof is collected in tanks, and sewage is treated and disposed to a soakage field.
But what has excited Mulholland most about the property is the wetland. It's rated significant by Horizons Regional Council and he can wander out in the morning in his dressing gown and see fernbirds in the raupo.
He's poisoned willows, killed predators and planted native trees, and he hopes the next owner will be equally enthusiastic.
"On most properties, you could spend your whole life planting and the next neighbour can cut them all down. Here that can't happen, because of the QEII Trust," he said.