Yarrabee

This property nestled in the hinterland of the NSW Central Coast is made up of flood plains, south-facing sloping paddocks and some vestigial rainforest, all of which is affected by mine subsidence. This triggers specific rules about the type of construction allowed, significantly influencing the project design and structural properties. 

The 380m2 homestead is a series of separate pavilions linked by covered decks, slung like a cradle from a focal point up the slope. Guest accommodation and corporate headquarters for the farm and the owner’s broader business interests stand adjacent. Each pavilion stands on its own independent foundation, designed in such a way that slabs can be jacked up to level in the event of future ground subsidence. 

The distinctive cross-pitched roofs are a response to the twin foyers that provide lightweight flexible connections between the separate pavilions. Each of these is transparent from north to south, offering easy physical access and views to the creek below. It also invites through breezes, important in the humid summer evenings experienced here.

The deep overhangs that create diverse outdoor living areas for different seasons are constructed using a careful mix of solid and clear materials. These variously expose the thermally massive building materials to sun in winter so they can store heat and buffer diurnal temperature fluctuations but block the sun in summer to avoid overheating. European style tilt-and-turn casement timber windows feature double glazing with argon-fill and low-e coatings that provide UV protection and greater energy efficiency.

As well as the exposed concrete slabs and selected deck paving materials, Timbercrete block walls were specified. These are made from a mix of sawdust waste, sand and a small amount of cement. They are insulated externally and largely left exposed inside the house. Timbercrete  provides a perfect mix of insulation and thermal mass in a natural low-embodied energy material. 

The use of these high thermal mass materials would seem to have been ruled out by the regulations that applied to building on land affected by mining subsidence (thermally massive materials are by nature very heavy). But Envirotecture persevered and our team’s highly technical solution produced the first full masonry building allowed on a mine subsidence site since the new rules were introduced several decades ago.

The house is passively heated and cooled, entirely self-sufficient for water, generates its own energy from PV arrays and much of the household’s food comes from their own gardens. Low embodied carbon emissions was an important criteria, with recycled materials and furniture in evidence, such as the beautiful ironbark timber floors.The roof structure is built from low-tech laminated plantation timbers.

We showcase this award-winning project from the ‘00s because of its use of natural materials—quite groundbreaking for its time—and for the way design overcame the challenges of the site.

2009 HIA Australian custom built home of the year — winner

2009 BDA NSW Award – Houses over 450m2 — winner

2009 BDA NSW ESD Award