When building waste becomes something new

A Hamilton building company is turning construction offcuts into homes - tiny ones, to be exact.

Sentinel Homes’ Waste Project will see one of its first two tiny homes go to auction in the next few weeks amid hopes of taking the initiative nationwide.

The project started about 10 months ago, says operations manager Jono Kraenzlin.

“At the time we were sending to landfill per site about 45 cubes of construction waste, which is like seven and a half tonnes per site. And across our 35 sites that obviously accumulates to a lot of construction waste, which is pretty common in the industry.

“So we thought, it’s such a valuable resource we wanted to do something different,” Kraenzlin says.

It’s estimated construction and demolition waste makes up 50% of New Zealand’s total waste going to landfill, and legislation changes from July 1 this year will require landfill operators and transfer to report the waste sources and local authorities to report on their spending of levy money and waste minimisation services and facilities.

PJ Haworth, who was involved in starting Raglan’s Xtreme Zero Waste - a resource recovery centre that diverts 75-80% of waste from landfill - joined The Waste Project as waste manager and a shed in Te Kowhai was leased to house the diverted building waste.

Haworth manages the waste on Sentinel Homes’ building sites, using customised bag stations to separate materials into what’s recyclable while everything else that is reusable gets stored in Te Kowhai.

Then came the idea of using the offcuts to build tiny homes, Kraenzlin says, as it could make use of almost everything from a site on a much smaller scale while also creating work for tradesmen and accommodation in a housing crisis.

The tiny homes are made using timber cut-offs, cladding offcuts or damaged or discontinued materials that would normally be thrown out such as flooring.

Surplus pieces of insulation batts that would usually go to landfill have also been used as well as windows and doors repurposed from demolition sites.

“You'd be super surprised at how much is gets thrown out, especially flooring. For example they'll discontinue a certain product but there'll be hundreds and thousands of them left over that they just can't anything with because that product line is discontinued.”

Since The Waste Project began last year, 60 to 80% of Sentinel’s waste has been diverted from landfill and is now either being repurposed or recycled at its Te Kowhai site. The project hopes to eventually reach 90%.

Twenty years ago it took Xtreme Zero Waste only a couple years to reach 75% waste diversion, Haworth says, and building waste was one of the things that stopped it going any further.

There’s still a percentage of construction waste that has no end life but Kraenzlin hopes the initiative will create awareness and put some pressure back on building industry and those producing the materials. “We'll recycle it but you got to give us the solution to what to do with it.”

The first tiny home built by The Waste Project will be placed outside Sentinel Homes’ show home on River Rd while the proceeds from the auction of the second home will go back into supporting the growth of the programme.

They are also in talks at the moment with different organisations about using the programme as a training initiative for apprentice builders, Kraenzlin says but at the moment the construction of the tiny homes is another way to create work for some of Sentinel Homes’ tradies.

“These two right here, that's two weeks worth of work for a crew of five builders. They otherwise wouldn't have had work so they're super grateful.

“And this is all stuff that would have been thrown away because of it's a defect or a cover sheet but it has created two weeks of work for five builders.”

The hope is for the initiative to go nationwide or to be rolled out in other regions.

If that means the programme is replicated by other companies, “it’s a win for us”, Kraenzlin says.

“For us, we just want less rubbish thrown away and less rubbish chucked in landfills and this is just one cog in the wheel to get that done.”