On the drawing board: Sand Dune Studio

The sisters behind Borgelt & Craig Architects have drawn on their experience in reusing spaces and materials to transform an underused garage into a cosy retreat.

The saying ‘never work with family or friends’ is certainly not true for us. Still in partnership after 20 years, it’s that deep family connection and understanding that drives our practice and has many of our clients returning with further projects. Through hands-on construction experience and research, our approach centres on ways to build for sustainability and flexible modes of living.

An active childhood full of outdoor adventures, camping and gardening means biophilic design and connectivity between built and natural landscapes is deeply embedded in our strategy. We believe that designing smaller homes with adaptable, shared, transitional spaces between inside and outside increases the liveability and joy of the site and allows for future living changes.

Our building experience started as necessary cost efficiency, as we salvaged materials for reuse on our own houses. We came to appreciate the high quality and beauty of aged timber such as that used to build our state’s quintessential Queenslanders and worker’s cottages. Reclaiming, reworking and adapting materials often means an additional upfront labour cost, but it’s worth the effort for a more durable, quality material full of history, character and unexpected delight.

This approach is even more relevant in the current construction market of cost increases, material shortages and delivery issues. By adapting, refitting and repurposing existing buildings and materials, we are devising cost-effective and waste-reducing ways to create compact, flexible living. Our recent project, Sand Dune Studio, was a satisfying opportunity to put all this into practice.

The project began when return clients found that their adult children and their partners and friends were overflowing the family beach house on North Stradbroke Island. The house sat perched on a steep hill, accessed by a path winding up from the street and past a garage they described as “unuseable”. No car could actually get up the hazardous driveway, and so the garage had filled up with storage boxes, bikes, surfboards and dive gear over the years.

“Can you do some magic?” our clients asked, as the garage door lifted.

The brief was for a comfortable retreat just for the two of them, where they could arrive on bikes off the ferry and stay for a night or a month, without the bother of cleaning an entire house. They desired privacy for sleeping, but also wanted to enjoy the surrounding native treescape, gardens and wildlife. Underlining these requests was a shared desire to be as sustainable as possible.

The garage was a timber-framed building with a truss roof, and a floor of hardwood sleepers laid directly on sand. We wanted to retain and feature the simple honest structure and reuse as much as possible, but the existing floor was not practical. Instead, we repurposed the sleepers for an outdoor courtyard. A combination of steps, seating and garden beds now lead up from the street, replacing the drive and making the area useable. The finished studio can also be accessed via the existing footpath to the main house up the hill. When the studio is occupied, a solid timber front door swings open to click into the side privacy screen, preventing anyone wandering in from the garden path unannounced.

The new 27-square-metre interior consists of an open adaptable sleeping/living space with a small kitchen, and a bathroom hidden behind. Built-in bench seats with storage underneath can be used as seating, daybeds, or for travel baggage unloading. A loft space offers additional storage over the bathroom. Glass and batten-screen doors slide away to open the living space up to the private screened courtyard, providing the couple with an expanded space for outdoor eating, an open-air office, or entertaining guests. Flexible transition spaces like this are pivotal in all our residential work, no matter the scale.

Island locations often present problems with material availability and transport, and finding skilled labour. Luckily the mild coastal climate of this Moreton Bay island allowed for a minimum palette of materials, and local connections found us a great builder, Caleb Cunningham. His skills and willingness to experiment with the materials we selected allowed us to get items like the joinery, timber sliding screens, seating and solid casement windows built on the island.

The material selection was based on affordability and sustainability credentials as well as toughness, and everything also needed to be locally sourced or easy to assemble and work with onsite. FSC-certified spotted gum is used for all the built-in cabinetry and timber-framed sliding doors. Kobe board – a highly compressed mix of sustainable plantation eucalyptus particles and some Portland cement – is used sparingly as a wall lining, only in high contact areas behind furniture, seating and the bed. Even though this material is easy to cut with standard woodworking equipment, we designed for whole sheets to reduce onsite cutting and waste. Plantation pine plywood sheeting has been used for the raked ceilings, set between trusses so the simple timber structure is still on show. And for the floor, the island’s concrete batching plant provided a new concrete slab that we burnished for low maintenance.

The steep bank of timber sleepers behind the studio posed a fall hazard, solved by cantilevering battened boxes out beyond the windows and over the gap (see photo on facing page). Screened with stainless steel mesh, these boxes protect against bushfire ember attack on this heavily vegetated side of the building, and also provide secure ventilation and drying areas straight off the bathroom and bedroom zones. It’s easy to throw swim gear and surfboards out there for secure storage and to have them dry for the next day’s use.

When adapting existing structures, optimum orientation for passive solar performance is not always available, but there are often other advantages to be found through existing landscape and vegetation. Here, there were benefits to the studio being nestled into the dune, which provides sound insulation and good thermal consistency all year round. The addition of a new concrete slab helps maintain this. Even though the studio’s main openings face west, the existing established trees and vegetation provide shade and privacy. We have been able to improve both of these elements further through the layered sliding doors and screens plus supplementary plantings. Plants endemic to the island were selected, with many purchased from the island’s Bushcare group.

There is an added benefit to this little studio: the couple can still stay on the property while the 40-year-old main house gets a much-needed repair and refresh. No additional outlay is required for alternative accommodation through the next stage of their building project.

And they are thrilled with the result, giving us this feedback: “By reimagining the existing footprint, Julie and Deb transformed a utilitarian garage into a warm, modern, tiny home – proof that thoughtful design can override a building’s origins and create something unexpectedly charming.”