| 95 BUILDING PhD Building Top award triumph for build system The sprawling Queenstown house, covering 820sqm, is built entirely with Nudura ICF, and took out a prestigious award at the 2022 International ICF Association annual awards in Las Vegas. T T Hugh de Lacy In a triumph for a building system still in its relative infancy in New Zealand, an Otago house has won a prestigious award at the 2022 International ICF Association annual awards in Las Vegas – and the Nudura system’s South Island distributor, Jeremy Chisholm of Queenstown’s PhD Building, couldn’t be happier. ICF stands for Insulated Concrete Forms, a system of formwork for reinforced concrete made from rigid thermal insulation, such as polystyrene (EPS) that remains in place permanently around concrete walls, floors and roofs. The forms are dry-stacked up to six metres high, and the steel reinforcing bars are placed in them before being filled with concrete. The EPS not only insulates the concrete inside but also protects it from weathering and deteriorating over time, so a building made of ICF could last for centuries. Nudura has a service life of at least 100 years, twice the current New Zealand code (subject to conditions). “Nudura ICF is exactly like giant Lego blocks that click together to create the formwork for concrete construction,” Jeremy says. The company imports 15 to 20 containers of Nudura ICF from one of four American factories every year and, while uptake of the technology in New Zealand has been fairly slow compared to the rest of the world – “A lot of our builders are pretty conservative,” Jeremy says – it’s now growing steadily. Jeremy also imports Estonian-made triple-glazed wooden-framed windows for his ICF houses, providing the perfect complementary joinery to give the highest level of thermal performance available from the two building systems. ICF first came to light in 1966 when a Canadian contractor, Werner Gregori, filed a patent for a foam formwork brick 401cm high by 122cm long, with tongue-in-groove interlocking, metal ties and a waffle-grid floor. Today the system is widely used globally and is part of most building codes and jurisdictions in the developed world. In North America it competes successfully against all forms of concrete construction in terms of speed and cost, with the added bonus of high levels of thermal performance and durability. Nudura’s parent company in the USA is currently rolling out a whole building envelope warranty of 60 years where Nudura ICF is used in conjunction with the full suite of products supplied. Last year the ICF body awarded a first-ever Unlimited Residential Award to a New Zealand home, the 820m2 Te Toka, near Queenstown. The sprawling home, the biggest ICF house in the Southern Hemisphere, is built entirely using Nudura ICF, with more than 980m2 of product used between the interior and exterior walls. The ICF installation took six weeks out of a total build time of 83 weeks, saving the builder, Dennis Dowling of DCD Construction of Queenstown, 16 weeks’ work as compared to a conventional build. The Nudura blocks used, whose cost is similar to that of standard concrete blocks, were 450mm high by 2.4m long, part of an annual output from four North American plants of three million metres of product, enough for 100,000 average houses. d e s i g n architectural design and draughting p b PROUD TO PARTNER WITH PhD BUILDING TO PROVIDE ENERGY EFFICIENT HOUSING 0211803844 phil@pbdesign.co.nz queenstown
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