96 | Hempcrete now in New Zealand Doug Sturrock: “There’s no telling the impact it will have on the New Zealand building industry, but it’ll be a big one.” Rockstead Construction: Geobind T T Hugh de Lacy BUILDING It was a building company with a vision of sustainability, but Kerikeri’s Rockstead Construction has been all but swallowed by its founder, Doug Sturrock’s development of Geobind, a locally-made mineral mix that has brought hempcrete building to New Zealand – and to its nascent hemp fibre industry. Doug, who grew up and completed a carpentry apprenticeship in St Andrews, Scotland, was otherwise twiddling his thumbs during the Covid lockdown when he discovered the extraordinary new building product, hempcrete, that was being enthusiastically embraced in Europe and North America, and was making an appearance in Australia. Carbon negative and proof against fire, damp and mould, hempcrete is made as a board or a brick from one third hemp hurd – the inner stalk of the hemp plant – and twothirds of a lime-based binder that cements the materials together. Hurd is a by-product of hemp fibre processing, and would otherwise go to waste. Until the recent establishment of a hemp fibre processing factory in Christchurch, hempcrete couldn’t be made here without importing both the hurd and the binder, prohibitively expensive then and now. With the sudden availability of hurd, Doug saw the potential to bring hempcrete construction to New Zealand too, if only he could create a binder from locally sourced minerals. Which he did with the help of regional development agency Northland Inc, a $250,000 arrangement with the Callaghan Institute to complete the research, and $30,000 in prize money for winning last year’s Business Innovation and Sustainability Award sponsored by Northland electricity generator and distributor, Top Energy. Roger had been a carpentry globe-trotter before coming to New Zealand in the early 2000s, and starting his company Rockstead Construction in 2006. He’d worked on historic buildings in Scotland and residential projects in France and elsewhere before ending up in New Zealand, doing stints in Queenstown, the Bay of Islands and Christchurch before settling in Kerikeri. There, with Rockstead Construction, he found a ready market for his residential builds that focused on climate sensitivity and sustainability, and the Covid lockdown gave him the opportunity to take those concepts further. Today magnesium-based Geobind, which is proven to outperform imported binders, is being produced in commercial quantities. At around $2500/tonne ex the Tokoroa factory, or in 18kg bags at $45 each, Geobind can be shipped to clients and timed with the arrival of hurd from the Christchurch factory. These homes would have virtually no heating or cooling requirements – hempcrete absorbs moisture from the air – and would last for hundreds of years. “With Geobind we’ve closed the hemp geo-fibre loop to complete sustainability by making use of every part of the hemp plant, and so we’re able to help others to innovate with hempcrete” Doug says. “We’ve taken up a waste product from the manufacturing process and turned it into a carbon-zero building product that excels in strength, stretch, durability, carbon sequestration and faster set strength. “There’s no telling the impact it will have on the New Zealand building industry, but it’ll be a big one.” BAY OF ISLANDS ITM WAIPAPA 411 Waipapa Road Phone: 09 407 8002 Open Hours: Monday to Friday 7:00am to 5:00pm, Saturday — 8:30am to 12:30pm BAY OF ISLANDS ITM PAIHIA 2 Haruru Falls Road, Paihia Phone: 09 402 7703 Open Hours: Monday to Friday 7:00am to 5:00pm, Saturday — 8:30am to 12:30pm BAY OF ISLANDS Proud suppliers to Rockstead Construction INDUSTRIAL | COMMERCIAL | RESIDENTIAL The cost-effective, environmentally friendly alternative to a Polystyrene foundation enquiry@cupolex.co.nz | 0800 287 6539 | ecodome.co.nz
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