Designed as a home for Woods Bagot CEO Nik Karalis, the St Andrews Beach Villa began in 1999 as a simple shack on Mornington Peninsula.
Over the years it has gradually evolved into what is now a five-bedroom villa with a pool, cabana, glasshouse and full-width deck.
"Longevity of design in historic houses is not unusual – many European villas took 10-30 years to build," Karalis told Dezeen.
"In our case, it was a combination of increasing family needs and also a detailed understanding of place and context."
Over time St Andrews Beach Villa has been adapted and altered to deal with its challenging site.
The peninsula is subject to intense winds, constantly shifting sand-dunes and a high concentration of salt in the atmosphere, which speeds up the corrosion of materials.
"The project could not be transported anywhere else in the world," said Karalis.
"It is a building intensely sensitive to place, recognised most importantly by the locals and the surf community."
St Andrews Beach Villa is a simple steel box raised on supports with a panoramic living space facing south-west towards the sea.
A 25 metre-wide stepped deck is cut through by a passage that leads into the undercroft, slotted below to provides a more intimate, sheltered space.
The villa's entrance sits on its sheltered rear facade, where a steel ramp leads up to a reception area and also to the pool and cabana.
Bedrooms sit arranged along this more sheltered, northern side of the plan, while the glazed front provides far more exposure.
This theme of contrasts continues in the exterior finishes. The rear and sides of the villa have clad with a rainscreen of jarrah wood panels, through which north light can filter in.
Internal finishes have been created through a mixture newer elements and old, worn materials from St Andrews Beach Villa's previous iterations
"The villa's ongoing deterioration inspired the material selections, and the details celebrate the temporality of all things," said Woods Bagot.
"A deliberate juxtaposition of eroded and resilient surfaces, of mundane and exquisite materials, reflect a sensitivity of a beguiling nature."
Although the latest stage of expansion has been complete, the practice still view the villa as an ongoing design experiment that will continue to respond to its site over time.
"There are still more areas of development in response to both the personal, emotional journey but also further sensitivity to the site's ecological potential," said Karalis.
"It could go on for a whole life time and into the next generation. Design never rests."
Woods Bagot has previously created several residential projects that respond to their environments through their form and materials.
Photography is by Trevor Mein.