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Timber Design Awards

Thorne Bay House

A three bedroom house designed for a small and near-impossible site!

Five well established pohutukawa inhabit the site, with intertwined limbs spread across the seaward half of the available building zone. A tight access lane drops from Minnehaha Ave at a very steep 1:3 slope. Much of the site is volcanic rock.

The desire not to damage the trees or their extensive root systems, combined with the steep slope and limited turning circle for cars, the rock outcrops, and the restrictions of height-to-boundary controls necessitated a process of complex analysis to formulate the actual possibilities for building. The result is an innovative building which and is squeezed under, around and between the limbs of the trees, and still manages to take full advantage of the site, the sun and the views.

The house is designed to change its character as it rises from the ground towards the sky. The ground floor level comprises orthogonal spaces, which follow the slope in a series of steps down towards the sea, providing sea views from each level and with the lowest level, the Living Room, set to ensure views across the stone boundary wall which provides privacy. Upstairs, the rooms become more angular and free flowing, to reflect the contortions of the pohutukawa limbs.

The ground floor contains the Living, Dining Kitchen area, Theatrette, Laundry, Bathroom and double Garage. The upper floor has three Bedrooms, two Bathrooms, and a Library. The Main Bedroom opens out onto an extensive rooftop terrace which weaves between the tree branches. The Library is projected out towards the sea like a tree house amongst the pohutukawas, propped on asymmetrical steel columns whose bases are carefully located to avoid tree roots. Much of the ground floor slab is suspended on a limited number of foundations also located to avoid tree roots. An irrigation system under the slab provides the equivalent water to the roots as if the house had not been built.

The use of Timber in the house reflects the importance of the existing trees on the site and provides visual warmth and softness. The exterior cladding is an integral part of the design and continues into the interior. The cedar weatherboards line the interior walls of the stairway, continuing along the upper level hall, and lead the visitor out into the cedar-lined ‘treehouse’ library. Oak flooring runs through the Living/Dining areas and up the stairs. Cabinetry is also oak veneer in the living spaces, bathrooms, bedrooms and library.

The cladding is a carefully detailed system, with the envelope clad in plywood on cavity battens, and then a rainscreen of open-jointed 130 x 20mm cedar boards added. These provide the visual cladding, protect the weatherskin, and offer a ventilated cavity which reduces the solar gain into the building through the walls. The cladding also wraps into the interior spaces to define spatial elements such as the ‘treehouse’ library.

Sustainability is evident in a variety of aspects of the design and materials. The wall and floor framing is generally timber. Vertical cedar fins are carefully located and angled over windows to provide solar protection and privacy from the neighbours, whilst still allowing wonderful views of the foreshore and sea. The cladding offers additional protection from solar gain and along with natural ventilation removes the need for air-conditioning. And the design of the house, location of footings, and underslab irrigation protects the existing trees, which would have been threatened by a more conventional design. All timber is from certified sustainable sources.

The complexity of the project necessitated very demanding construction detailing which was beautifully built by Gary Bonham Builders. The house was recently a Gold Medal Winner of the 2009 Registered Master Builders Auckland Regional Category for homes over $1million and is also Finalist in the 2009 Registered Master Builders National House of the Year (to be announced in November).