Concrete … a tough material for a rugged environment
Images courtesy of ArchiPro
The brief
Ross Sweetman, Associate and Senior Designer for Dalman Architects says that due to the remote location the design had to create a feeling of safety that would be comfortable and warm for the owners and, from the inside looking out, would offer a mostly unobstructed view of the landscape.
“The client loved the idea of a bunker style home and the use of concrete for the exterior and interior walls and ceilings,” says Ross. “Another key requirement was the need for a home that intentionally blended into the surrounding landscape, minimising its visual impact - which did lend it itself to mostly underground design. This was to also to protect the unique visual characteristics of the surrounding scenic grasslands area, and the integrity of the internationally recognised ‘dark sky’ area near Mt John Observatory. The design includes a glazed facade which is positioned away from the observatory, ensuring no light pollution would disrupt the night skies.”
Making it happen
Ross says that this unique design presented significant construction challenges due to its isolated location. “During the design stages we met with the client, Structural Engineer and the builder (Wilson Building, Timaru) at the premises of Thompson Precast (both longstanding customers of Firth in Timaru). With input from all of the project team, it was decided to precast most of the building elements to minimise the risks associated with pouring concrete into form work on such a challenging and remote site. The precast panels were made at the Thompson Precast yard using ‘Oregon’ boarding in the timber formwork and once installed on site were joined on site with sections of insitu concrete with a matching board form finish."
“Trying to set up and pour all the various panels for the walls and ceilings insitu would have been very difficult and risky the project, and precasting allowed the quality to be ensured before panels were delivered to site. Wilson Building did a great job of the precast panel installation and their insitu concrete work matches the textured precast panel appearance perfectly.”
The result
The building's interior is dominated by board form, exposed concrete. The above-ground portions are cleverly concealed by the surrounding fauna, resulting in a design that creates a truly hidden structure, seamlessly integrating into its natural environment all year round.
Originally conceived as a holiday home, the ‘bunker’ has evolved into a permanent residence. The design features a simple yet versatile layout centred around a kitchen, living and dining area. Two bedrooms, each with its own ensuite, flank this central space. A third bedroom, which will eventually serve as the primary entrance when the tunnel to the nearby airstrip and hangar is completed, is located at the rear.
“Using concrete for this home was absolutely the right material of choice for this design and shows how concrete can be used to create a robust, energy-efficient, and visually striking home that interacts seamlessly with its environment,” says Ross.
Why use concrete?
Structural Integrity
- The house is built using reinforced concrete, ensuring exceptional strength and durability against the region's harsh weather conditions, including strong winds, heavy snow, and seismic activity.
- The concrete structure acts as both the primary support system and the defining visual element.
Thermal Mass and Energy Efficiency
- Concrete’s high thermal mass allows the house to absorb heat during the day and slowly release it at night, reducing temperature fluctuations.
- This is particularly beneficial in the Lake Tekapo region, where temperatures can vary significantly between day and night.
Minimalist and Brutalist Aesthetic
- The exposed concrete surfaces give the house a raw, industrial feel, emphasising a bunker-like appearance that harmonises with the surrounding rocky landscape.
- The material's natural grey tones blend with the terrain, reinforcing a connection between built and natural environments.
Durability and Low Maintenance
- Concrete is highly resistant to moisture, pests, and fire, making it ideal for the often-extreme conditions of the region.
- The reduced need for maintenance compared to timber or steel construction makes it a long-term, sustainable choice, and concrete can easily be recycled at the end of the building’s life.
Integration with Landscape
- The house is designed to be partially embedded into the land, enhancing its bunker-like characteristics.
- This semi-subterranean approach not only improves insulation, it also minimises visual impact, allowing the home to almost disappear into its environment.
Builder: Wilson Building, Timaru
Concrete Precast: Thompson Precast
Architect: Dalman Architects
Structural: Meyer Cruden Engineering
Location: Mt John, Lake Tekapo
Product: Firth Certified Concrete