Like a Tetris Game, an Australian Extension Locks Old With New

A rear extension makes this bungalow in a Melbourne suburb more suitable for a growing family.

In the suburb of Ascot Vale, northwest of Melbourne, architect and photographer Jaime Diaz-Berrio teamed up with architect Mark Allan of Crosshatch to create a 484-square-foot rear extension for a two-bedroom bungalow. The reconfiguration and expansion of the now 1,560-square-foot residence adds a third bedroom, bathroom, and central living lounge.

This is the second project that Crosshatch has designed for this client, a young family who love the character of their old Californian-style bungalow but realized they needed more space for their growing children. 

"We were tasked with extending the house in a sensitive way, respecting the existing building, and providing a modern kitchen /dining and laundry whilst reconfiguring the existing interiors to add another bedroom, " says Jaime Diaz-Berrio.

The south-facing extension, which contains a new kitchen, dining area, and laundry, captures the northern light through the introduction of a central courtyard and strategically positioned windows.

Although the orientation of the site was not ideal as the extension faces south, the strategic location of the addition and high-level kitchen window draws sunlight deep into the space in winter, while the deep window reveals restricts sunlight penetration in the summer months.  

The duo named the project Tetris Extension because the forms of the new addition are arranged in a Tetris-like configuration that’s expressed in the plan, elevation, and section. 

One side of the exterior is clad in spotted gum timber battens.

Recycled red bricks are used for sections of the exterior walls.

"The interlocking volumes unite the form and function of the old and new," says Allan. "The Tetris concept is further iterated through the interior detailing, including bespoke cabinetry and custom kitchen door handles."

Interior walls and ceilings are plasterboard with a paint finish.

Existing timber floorboards in the old house were sanded and re-polished.

The house’s original Californian bungalow facade was retained, so the modern extension is not visible from the street, and only reveals itself as the user walks through the old house.

The floors in the extension are hydronic-heated, polished concrete.

A polished concrete island bench contrasts with oak timber cabinetry in the kitchen.

The additional 484 square feet allowed the architects to reconfigure the floor plan to accommodate three generous bedrooms, two bathrooms, and a sun-drenched, central courtyard that can be accessed from the kitchen/dining area, living room, and the kids’ play room. 

Custom-designed timber handles reinforce the Tetris concept. 

A built-in bench wraps around a corner as seats for the dining table.  The artwork is by watercolorist Stefan Gevers.

The backyard, which was previously completely disconnected from the house, is now integrated into the design with large window openings that enable the interior spaces to flow out beyond their physical boundaries.

Shop the Look
Large Sheepskin Throw
This natural, ethically sourced sheepskin comes from the Northwest coast of Ireland, a region known for incredibly soft and dense sheep’s wool.

Oak timber recessed ‘boxes’ are used as bookshelves, wine storage, and display cabinets.

A simple material palette of polished concrete, white surfaces, and timber details create a light, warm, neutral space that’s enhanced by colorful artwork and homeware—and plenty of natural light.  

The 15-foot window in the extension is the focal point of the project, as it marks the connection with the existing house, creates a substantial volume in the kitchen, and frames views out to the beautiful gum tree on the rear property. 

The stucco ceiling in the bedroom was restored.

The aluminum window frames are by Windows by Design.

"Working with an old building always poses a few challenges, as you never know what you might find once construction starts," says Diaz-Berrio. With this in mind, he and Allan ensured that their intervention only "gently" touched the existing building with minimal structural alterations. 

The shower is by Astra Walker.

The Inspira Round Vessel bathroom basin is by Roca.

"Our self-imposed challenge was to resolve the family’s functional requirements in the most efficient way whilst creating a memorable living environment," he says.

Tetris Extension old floor plan

Tetris Extension proposed floor plan

Tetris Extension existing roof plan

Tetris Extension proposed roof plan

Project Credits:

Architecture and interior design: Crosshatch /

Builder: Loft Property

Structural and civil engineering: WGA

Stylist: Style Warrior Interiors, and Ally Batties

Artwork: Stefan Gevers  


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