The house is located on a very steep site overlooking the Pacific Ocean on Sydney's Southern coast line. Designed for a young family the challenge was to connect the house to the garden, bridging a significant height difference. Due to the steepness of the site the pool sits on the living level, high above the ground in the middle of the house. The associated structural, waterproofing and sound issues were complicated to resolve, but in return the children can be easily supervised when playing in the pool.
The house is built deep into the rock. Even though the levels step east, towards the ocean, as they progress down, parts of the lower levels don’t have the opportunity for windows. To still bring day light deep into the core of the house a series of large voids connects all five levels of the house, visually, with daylight, and functionally, also containing the central stairs spine.
The top, entry, level contains a large four car garage, a guest bedroom and of course the entry zone. A living area is on the level below, together with a media room and a large deck. The deck is supported to the east by a large, yet slim, concrete beam, spanning approx 13m. In order to keep the area below as free of structure as possible this beam has is post-tensioned. Typically a structural method for larger buildings this allows for an open plan layout on the level below, the main family level containing Kitchen, Dining and an informal Living area as well as a large deck, and, of course, the large, 20m long, swimming pool. The entire slab above is supported only by a single steel column and said post-tensioned beam.
Between the street and the western edge of the building a double-storey courtyard allows for daylight and natural ventilation.
From here on down the void and the stairs narrow, to indicate the increased privacy of the lower levels. The level right below the pool contains three bedrooms with associated functions and a large Gym and Sauna for the sporty family, while the lower, bottom, level offers another two bedroom and the husband’s “Man Cave” with a large golf simulator. Also located in the inner parts of that lowest level are Laundry, Plant Rooms and other ancillary functions.
This level connects to the garden some 20m below street level, via a large deck and stepped landscaping terraces towards the rocky ocean shore.
In order to ensure sustainability in this severely corrosive marine environment material selection was critical throughout the process. 40MPa concrete was used for exposed structure, a mix with a high fly ash content and a min 45mm steel coverage for long-term corrosion proofing. This will ensure that the concrete will not only age well but also not require any maintenance over its life time.
Where insulation was required outside the concrete walls acrylic render was applied over a fibre reinforced primer. All glazing framing is 25 micron anodised, low-e with high U-value. Any Stainless steel used is 316 marine grade, electroplated where critical. While these material choices came with additional cost the expected longevity of the house, together with the reduction of maintenance requirements, made these also viable economic and sustainability decisions. Not only is the house built to last, but it is designed to accommodate their working and recreational needs, as well as the changing requirements as the children grow up.