The latest innovations in concrete slab foundation

The world of concrete slab foundation in new builds involves a slew of complex processes and stages, with various disparate methods available to achieve it. Some methods have more benefits than others. Traditional externally-braced foundation boxing has wooden shutters that go around the perimeter to hold in the concrete. Then, after the concrete is poured, the inevitable messy task of stripping off the formwork must begin. This is to say nothing of the insulation — in some cases, the slab is not thermally broken, and utilises not-so-eco-friendly polystyrene insulation. Next-generation foundation systems have sought to build fixes to these issues. Many have addressed one or the other, but few have sought to tackle each of them in a single solution. QPOD coupled with QuickSet is one of the few. It’s a patent-pending, fully insulated, internally braced, permanent formwork system that can exist either as a fully-insulated system or as edge insulation alone. The combination of a fully insulated panel with a permanent formwork that requires no messy removal is a “game changer”, says QuickSet general manager Nicola Hall. “There are no pegs or waratahs around the outside of the foundation,” says Nicola. “All you need to do is set it up, put in the insulation pod systems and pour the concrete — and that’s it. You don’t need to come back to strip the formwork. It does the boxing and provides edge insulation at the same time — two birds, one stone.”

When it comes to foundation structure, QuickSet’s preferred pod system is QPOD — an earth-friendly alternative to the conventional polystyrene pods. Unlike polystyrene, QPODs are hollow, which means they can easily be stacked and transported. The pods are recyclable and are made from 100% recycled plastic in the company’s plant in Hawke’s Bay, and they further cut down on wastage as they don’t need to be cut to size when they arrive on site. Used in conjunction with the QuickSet solution, the pods are placed next to one another to form a grid, with reinforcing steel bars placed between them. The concrete is then poured as normal, under which the QPODs create the tried and proven pattern of ribs that make up the raft foundation. But the true advantage of combining the expertise of QuickSet and QPOD is the enhanced benefits when it comes to insulation. With the new H1 Building Code changes, no longer are all foundations deemed to hold a minimum R-value of 1.3: each foundation must now be calculated on its area to perimeter ratio to determine its R-value — and this must reach a minimum R-value based on which climate zone the building is in. For climate zones 1, 2, 3 and 4, which includes Auckland, Wellington and the West Coast among others, the minimum R-value for concrete slabs on the ground with no underfloor heating will be 1.5. For climate zone 5 — including Canterbury and parts of Otago — the minimum R-value is 1.6, while the colder parts of Otago and Southland, in zone 6, will have a minimum R-value of 1.7. Luckily, there’s a simple way to figure out what systems need to be installed on a building to achieve the minimum R-value. QPOD’s website features an innovative calculator, where users can input the area of the footprint and lineal metres, and it will calculate the area to perimeter ratio. If the ratio of perimeter is large relative to the total area, the R-value will decrease. QPOD sales manager Peter Crawshaw says the calculator allows users to choose their target R-values. “You can input your areas, even if it’s a complex-shaped house, and it spits out the R value achieved for each of the QuickSet solutions, helping you choose which is best suited to the project,” says Peter. “It makes it really simple for anyone to work out what they need.”