A 3D-printed test house in East Austin demonstrates new possibilities for construction.
Client and 3D-Printing Technology ICON
Architect Lake|Flato Architects
Structural Engineer Guy Nordenson and Associates
MEP Engineer Integral Group
Lighting Design Studio Lumina
Envelope Consultant SGH
Material Science Wiss, Janney, Elstner Associates
Landscape Architect Word + Carr Design Group
Human creativity is the driving force behind architectural innovation, but recent technological advancements have increasingly helped push the bounds of that creativity. In the past five years, opportunities for 3D-printed construction have grown, resulting in the development of an entirely new design language. House Zero is a translator of this language, showcasing the design and performance capabilities of 3D-printing technology through organic forms with luxurious finishes.
The project is located at the edge of East Austin’s Holly neighborhood. As a demonstration house in ICON’s exploration series, it has no permanent residents but receives a steady stream of visitors. While its celebrity status might suggest otherwise, House Zero is not ICON’s first project in the area. In 2018, its Chicon House became the first permitted 3D-printed home in the United States. Since then, the company has completed several affordable and market rate residential projects in and around Austin. Breaking new ground, House Zero aims to prove that 3D printing can also be used in high-end construction. Jason Ballard, CEO of ICON, co-founded the company with the goal of addressing the issues of wasteful construction and rising housing costs. Through its work, ICON seeks to promote a new standard for robotic construction and encourage designers to explore new applications for 3D printing.
To achieve this dream, ICON is leading by example. The company commissioned Lake|Flato Architects, a local firm known for its commitment to sustainability and site-specific architecture, to design the house. “We were interested in the design of a home which has been optimized for 3D-printing design by exploring how organic, sinuous geometries can be an inherent part of the architecture,” says Melodie Yashar, vice president of building design and performance at ICON.
Unlike conventional construction methods, 3D printing can produce a curved wall for the same cost as a straight one. It is no surprise, then, that House Zero possesses several “wiggly walls” that accentuate the material qualities of the space. The resulting composition eliminates the 90-degree angles that govern most residential designs, instead employing rounded corners that encourage organic circulation patterns. Curvilinear details are found throughout the home, such as in the bathroom vanity and millwork, creating a cohesive aesthetic across scales. The design admits an abundance of natural light and promotes indoor-outdoor connectivity in a deliberate attempt to challenge the conception of a concrete house as “cold” or “cave-like.” The formal qualities of the test house demonstrate the extensive capabilities of ICON’s 3D-printing technology, showing that it can do what conventional construction methods cannot.
Every exterior wall in House Zero is 3D printed using ICON’s proprietary cementitious material, Lavacrete. Developed by the company’s in-house materials science team, the substance is both highly printable and very durable — a difficult balance to achieve. For this project, ICON used Magma, a portable mixing unit that prepares Lavacrete. Magma actively monitors on-site weather conditions, and ICON adjusts the formula accordingly in 15-minute intervals.
Lavacrete is pumped from Magma into Vulcan, ICON’s large-scale 3D printer. The printer is designed for rapid transport between sites and can print directly onto the ground or a poured slab. The width of House Zero was limited by the size of Vulcan; the printer itself is 15.5 by 46.5 feet and can print a volume up to 10.5 feet tall, 38 feet wide, and 100 feet long. House Zero fits snugly within these dimensions.
The walls of a 3D-printed structure are built up simultaneously, extruded layer by layer in accordance with instructions provided by BuildOS, a software series developed by ICON. The program translates floor plans into print jobs, facilitating high-precision parametric design. “Our design-to-print workflow at ICON is embedded in building information modeling approaches, where we produce a digital twin of the architecture to coordinate all elements of design,” says Yashar. A virtual design environment allows team members to work from the same model, ensuring cohesion between all mechanical systems. BuildOS helps designers coordinate at what point traditional construction components should be placed within the print, and determines the overall print path of the wall system. After the architectural forms are prepared for printing, BuildOS controls the robotic hardware of on-site machines across multiple device interfaces. This process enables machine learning and predictive analysis; BuildOS and the Vulcan construction system improve with every print.
The 2,000-sf house, which includes three bedrooms and two-and-a-half bathrooms, took only 10 (non-consecutive) days to print, and the ICON team notes that the process would have been faster if a week’s worth of heavy rain had not hindered their progress. Twenty-four-hour printing would have shortened the timeline as well, but the team only ran the machinery during the day. The lot is also home to a one-bedroom accessory dwelling unit, which was printed at the same time. A short construction period is one of the many benefits of 3D printing that ICON seeks to promote in its work.
Before printing could begin, a form-fitting foundation was poured with the help of CNC-milled formwork. After the wall print was completed, a metal roof with a deep overhang was built to shade a trio of floor-to-ceiling windows on the front facade, reducing solar heat gain. The protruding beams of the roof structure create the illusion of a wooden plane floating atop the concrete walls. Three undulating cylinders dominate the facade, alluding to the spatial quality of the interior. Despite its complex footprint, House Zero has been simplified down to the material essentials; its raw palette of concrete and wood is expressed proudly both inside and out.
The interior is defined by a blend of the midcentury modern and ranch house aesthetics. To ensure that all eyes are on the printed walls, the rooms are staged with modernist furniture in muted tones. The electrical and plumbing components are relegated to the floors and ceilings so that the walls may remain uninterrupted. There are a few small imperfections in the walls, including prominent air holes and uneven layers. These walls would not pass ICON’s standards today; the technology has progressed so rapidly that this field test is already a relic of past technologies.
To avoid homogeneity, some of the walls have plaster coatings in shades of cream or dark gray. Wooden cabinetry and shelving in the hallway, office, and kitchen spaces also provide material variation. Doors and windows are placed strategically to accentuate the landscape. Notably, these openings extend from foundation to ceiling because gaps were left for them in the master print. Breaking with this pattern, though, are the eastern-facing clerestory windows in the living room, which were incorporated into the design of the roof. The admission of indirect natural light reduces the need for electric lighting during the day. Just below the clerestory, a concealed MEP spine contains all of the house’s mechanical systems.
The undulating wall of the main living space neatly divides the open floor plan into three separate spaces: dining room, living area, and office space. The dining room is almost completely circular, creating a surprisingly cozy seating arrangement. The most common reaction on tours is one of pleasant surprise; the interior is not echoey, and evenly distributed natural light warms the house. ICON even invented a custom candle scent for House Zero to enhance the sensory experience of the space. Nods to the construction process are incorporated in the decor — material tests from several 3D-printing projects adorn the bedroom bookshelves.
The curved walls of House Zero are formed by three wythes of Lavacrete and reinforced both horizontally and vertically with rebar. Their self-stabilizing form makes them more secure than straight walls during extreme weather events. Insulation is inserted around the structural components. “Our wall system maintains high thermal mass, which slows heat transfer into and out of the home,” explains Yashar. Such walls are better equipped to handle temperature swings, and their airtight nature increases the energy efficiency of the build. An in-house team at ICON monitors the project’s environmental performance, and has reported that even during a winter freeze, House Zero maintained a steady temperature of 58 degrees. In a city where freezes are known to wreak havoc, this is a promising report.
ICON’s dream is to resolve the housing crisis while addressing issues of affordability, material waste, and energy efficiency. These lofty aspirations cannot be reached in a single project, but the technologies used in House Zero have already been upgraded to meet ICON’s continually rising standards of excellence. “Every project we undertake introduces new lessons learned and case studies for our future builds,” says Yashar. For ICON, House Zero is ground zero for the development of an architectural future built on resilient, sustainable 3D printing.
Abigail Thomas is an undergraduate student at the University of Texas at Austin School of Architecture.