Renovation On The Sly: Same Footprint, Twice The Volume

Christopher Polly’s eco-renovation of the Cosgriff House is a study in thrift.

Families grow and need space to stretch out. Just not in the last few years; economic woes halted people’s enthusiasm for renovation projects. That’s poised to change: Home improvement spending is expected to bounce back, post-recession, at the rate of about 17% this year. In response, architects are being calculated about what they propose: renovations that are beautiful but easy on the wallet.


Christopher Polly‘s overhaul of the Cosgriff house doubled the size of the property–but is neither a gut renovation nor a showy extension onto the original home. To turn the two-bedroom, one-living-room house into one with double of each, the architect, based in Sydney, Australia, decided to insert a living room on the ground floor, where a foundation didn’t exist. Intent on preserving the original shell of the home, Polly decided to embed the new room into the original footprint.

“A lower ground living volume is sensitively inserted beneath the original fabric to harness the fall in the site towards the rear,” Polly tells Co.Design. The new room transforms the house by extending “beneath the existing dwelling, and outwards towards the garden.”

Polly took pains to push the new structure into more environmentally friendly territory. A box of windows on the roof improves access to natural sunlight, and the house operates on passive ventilation (with assistance from ceiling fans and a roof venting system). He salvaged demolished bricks, then upcycled them into the masonry walls. Polly also built in clandestine rainwater reservoirs for watering the garden, and solar energy fixtures for hot water. Water-saving fixtures and energy-efficient light fittings are scattered throughout the house.

Green features aside, what really impresses is the subtlety of the renovation. The original home is packed in tightly next to neighboring structures, so any expansion risks disrupting the street aesthetic or blocking sunlight from other homeowners’ yards. It does neither. The Cosgriff House is as humble as they come–and it’s two homes for the look of one.

About the author

Margaret Rhodes is a former associate editor for Fast Company magazine.