Construction on Chattanooga’s First 3D-Printed Home to Begin in July
Michael Molitch-Hou posted on May 04, 2016 | 5602 views

Last year, at the GIGTANK startup accelerator pitch event in Chattanooga, Tenn., one startup made a big impact, figuratively and literally. There, Branch Technology presented their novel 3D printing technology designed to disrupt the global construction industry: a 25-ft-wide, 58-ft-long 3D printer capable of 3D- printing complex architectural components. 

Along with their Cellular Fabrication (C-Fab) 3D printing platform, the Chattanooga startup also announced the launch of a crowdsourcing competition seeking blueprints to lay the groundwork for their first 3D-printed building. On April 22, Branch Technology unveiled the winner of the Freeform Home Design Challenge, which will see the winner’s design actually constructed.

The C-Fab process allows for the freeform 3D printing of structural scaffolds. (Image courtesy of Greater Chattanooga/YouTube.)
The C-Fab process allows for the freeform 3D printing of structural scaffolds. (Image courtesy of Greater Chattanooga/YouTube.)

What makes C-Fab different from other forms of 3D printing for construction is the use of an industrial robotic arm, and also the fact that 3D printing is only used minimally for the fabrication of architectural components. 

Branch Technology’s 3D printer features a customized Kuka KR 90 robotic arm attached to a nearly 33-ft-long track on which the arm extrudes carbon fiber-reinforced acrylonitrile butadiene styrene (ABS) plastic structures up to 8,772 cubic ft in size, which makes the C-Fab printer possibly the largest freeform 3D printer in the world. (To help you visualize the size of these massive ABS structures, a 40-ft shipping container has a volume of 2,391 cubic ft—the C-Fab can create structures over 3.5 times that volume!)

The machine doesn’t 3D print complete buildings, however, but rather the inner framework for an individual component, such as a wall. The structure is then sprayed with traditional building materials, concrete and foam insulation. Interior and exterior finishes, like sheetrock and stucco, can be applied to the walls to create the end result.

The 3D-printed interior scaffolds can be sprayed with low-cost building materials for greater structural integrity. (Image courtesy of Greater Chattanooga/YouTube.)

The 3D-printed interior scaffolds can be sprayed with low-cost building materials for greater structural integrity. (Image courtesy of Greater Chattanooga/YouTube.)

This hybrid construction technique allows for the structural integrity supplied by concrete, while leveraging the benefits of 3D printing, greater geometrical complexity and reduced weight. In a previous interview with Branch Technology, founder Platt Boyd explained that their walls had the same strength as a traditionally made concrete wall, at more than 3,000 pounds per square inch, but were much lighter. A small, 1.5-pound plastic wall was able to support 1,500 pounds, while a 2.5-pound plastic wall with spray foam could support 2,980 pounds. 

Both of these examples were tested without concrete, yet the walls were able to support a great deal of weight due to the lattice framework of 3D-printed interior. The 3D printing process allows the Branch Technology team to sacrifice material while still maintaining structural integrity through the crisscrossed lattice design.

Branch Technology envisions the series production of the individual components for a given construction project, such as all the walls of a building, will be performed at their own facilities. The parts would then be shipped to the construction site, made easy and low-cost by the reduced weight of the 3D-printed walls, where they would be assembled into the final structure. Naturally, this scenario lends itself to the construction industry, but Branch Technology believes their technology could be implemented for just about any industry in which large-scale objects are required, such as aerospace.

By the time they presented their startup to GIGTANK investors, Branch Technology had successfully scaled up their technology, but had yet to 3D print components for complete buildings. Additionally, the firm would have to ensure that their C-Fab process could meet the guidelines and safety standards set forth by the International Code Council, which approves load-bearing construction products.

But, before Branch can begin these operations, there are a host of construction guidelines and safety standards that their new C-Fab process must meet, from the International Code Council. In turn, the startup would have to perform a number of American Society for Testing and Materials (ASTM) tests to submit to the ICC for certification. 

A representative from Branch Technology says that the firm is currently undergoing ASTM testing and are planning for further ICC certifications as required for the house and for the production of a number of loadbearing architectural components.The fact that they’ve announced the winners of their Freeform Home Design Challenge and plan to begin construction in July 2016 suggests that they are making progress.

The first-place winner of the challenge is a design dubbed “Curve Appeal,” a single-family home concept from architecture firm WATG Chicago. The cave-like Curve Appeal home consists of 28 individual panels that would be 3D-printed by Branch and then assembled on-site. In addition to having their concept 3D- printed in Chattanooga, WATG will take home a cash prize of $8,000. Runners-up “Home(less)+House” and “Urban Leaf” will not be constructed, but will earn their designers $1,000 each. As Branch Technology prepares to 3D-print Curve Appeal this July, the startup is seeking supply partners for its project.

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