Difra Thinks Different about House Design and Construction
Wouldn’t it be great to design and build your own personal house, real cheap? It may sound like a dream, but not for much longer. Difra, a Cambridge, MA, company co-founded by graduates of MIT, is working hard to fulfill this ambition.
Their idea is to use computer-aided design and manufacturing software (CAD-CAM) to model new houses in 3D, then translate the designs into kits containing all the flat 2D components needed to build them—in this case, engineered wood boards that interlock via so-called “friction joints.”
“To transform 3D to 2D for a typical, average-sized house of 1,600 square feet consisting of several thousands individual components is a very demanding task if done manually,” says Difra co-founder Morris Cox. But automation cuts the cost and the complication down to size.
Difra will sell its system directly to individual home buyers—and it already has some clients lined up. “Although our aim is to provide ordinary people with personalized homes, we will initially build more luxury homes, to show what can be done and gain acceptance among a broader audience,” says Cox.
“My dream is to enable people, even on limited budgets, to personalize their homes, to allow freedom in design,” adds Cox’s co-founder Lynwood Walker. “Light and color, form and feeling, we let people have it the way they want it.”
The team dug into a CAD system called Rhino—chosen for its ability to model surfaces and export data as CAM files that can be used in fabrication machines—and wrote algorithms that translate designs into practical plans that can be built using friction joints, which fit together using only glue.
Once a Rhino model is transformed into drawings of the fundamental 2D components, the 2D files are fed to a laser cutting machine. Pieces are cut and numbered by the machine. All the pieces are neatly packed and sent to the construction site, together with assembly instructions.
“Building a home is like laying out a giant 3D-puzzle”, says Cox. “It is the perfect community project. Most of it can be done by ordinary people. We see it as a rewarding and socially enriching project for neighbors, relatives or other groups.”
Cox estimates that a small house or cottage can be put together in no more than a couple of days. Where basic housing is needed, such as after a flood or earthquake, simple models can replace tents and primitive shelters.
With friction joints, nails are eliminated. Since the components are cut with laser accuracy, they can be forced together with a rubber mallet. Glue can be added to strengthen the joint. (The friction joint design that Difra uses is based mainly on expired Swedish patents.) ”$600 for materials is all that is needed for a small house,” says Walker.
Additional costs are incurred for surface treatment, piping, electricity, and so forth. But even the design, cutting, and placement of pipes and siding will eventually be automated using CAD and laser cutters, Walker says.
Cox and Walker say Difra’s approach is environmentally friendly, since cutting the engineered wood, called steam board, produces less waste wood compared to ordinary construction methods. Depending on local climate and circumstances the steam board may be prepared with anti-termite or anti-fire agents or other substances for special needs.
Given that Difras’s technology could make building homes cheaper, easier, and greener, there ought to be a market for it—but it’s unclear, so far, how the conservative building industry will react to the idea.
“The reason why prefab homes haven’t caught on in the past is because of unappealing designs,” says Walker. “They have been too boxy and identical. Our houses are not factory built, but rather factory cut—that’s a significant difference. We offer an almost endless variety in designs.”
So far, Difra has designed a number of models, and the first full-size prototype, a 600-square-foot small house, is on the way. It will be built in Boston within the coming weeks, on seaport space donated by the City of Boston.
The firm intends to oversee the manufacturing and construction of the first batch of houses itself. Customers are free to hire their own architects, but Cox and Walker say they can offer design and architectural expertise as well. Difra hopes to staff up with more employees soon, and is in fundraising discussions with real estate firms, software entrepreneurs, and angel investors, according to Cox and Walker.