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Tree House
Sydney Open Symposium: House Tours
Sunday 24 May 2026
A sustainable and resilient retrofit that has future-proofed a 1900s cottage for a changing climate
About the building
Tree House is a sustainable and resilient retrofit in the leafy inner-city suburb of Forest Lodge. Sited between a heritage sandstone wall, a park and neighbouring houses, the home comprised a 1900s cottage with a more recent addition at the rear. With single-pane glass windows, no insulation and a structure that was close to collapsing, the house required extensive work to make it liveable and future-proof it for a changing climate.
After purchasing the property in 2022, the owners were determined to approach the renovation as sustainably as possible, preserving what they could of the home, and reusing and salvaging removed materials where feasible. The two front rooms of the cottage were retained and made almost airtight, with insulation added to the existing timber floor and roof. The timber-framed windows were upgraded with vacuum-insulated glass, which performs at a triple-glazed window standard.
The more recent addition was deconstructed and rebuilt as a two-storey multipurpose dwelling separated from the cottage by a central courtyard. A material palette of galvanised steel and recycled hardwood and brick references the adjacent bush regeneration site, while a smart membrane wraps around the structure to create a high-performance envelope that manages moisture.
Outside, permeable batten fencing and native planting allow biodiversity to filter between the home and its lush surrounds. Over time, some of these plants will grow to envelop the house, adding an extra layer of heat protection as the home recedes into the landscape.
The house is powered using solar panels, is all electric, and collects rainwater for gardening. Paired with the design interventions, these features enable the home to run at net zero in operation, while the retention of part of the original structure and the reuse of materials found on site means it has 69% less embodied energy than the Australian new-home benchmark.
Tree House is both a remediation and a transformation, providing a pathway away from demolition that is in step with best-in-class residential design.
Architect/Designer
Alexander Symes Architect
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