When you build on a slope with anything more than a 20-degree gradient, the normal solution is to construct a house that sits on poles. So the proposal to build a conventional house on a 45-degree slope took many people by surprise. Even in Wellington, where clinging to a cliff-side is part of everyday life, this seemed daring. But this is exactly what architect Nic Ballara planned to do for his own family home.
As seen on series one of TV3's Grand Designs New Zealand.
Material COLORSTEEL® ENDURA®
Ensuring maximum stability on the slope was essential. COLORSTEEL® products were chosen because of their strength and rigidity, combined with their relative light weight.
A suspended Hibond tray and concrete slab for the garage faces the road at the top of the cliff. These attach to a 12-metre vertical concrete slab that drops down the cliff face and bears the bulk of the house’s weight.
Eleven steel ties spread over the area and anchor deep into the cliff securing these elements. This combination of infrastructure and balustrade reinforcement is grounded in a small foundation 17 metres below the road.
The versatility of COLORSTEEL® opened up a world of opportunities when it came to aesthetic design. The COLORSTEEL® roof folds from 15 to 77-degrees as it wraps the downhill wall. This gives the structure a sense of flow. The home, which boasts just one square corner, also featureS a glass wall that stretches over four levels.
In terms of earthquake proofing, the house is probably the safest on the street. The build exceeds all current maximum standards and is engineered to withstand stresses more than ten times its own 30-tonne weight.
COLORSTEEL® ENDURA® FlaxPod® in a Metalcraft profile was chosen for the roofing and cladding, with AXXIS® steel framing for the house and Speedfloor steel floor joists.
Architect BBC Architects