Puzzle House: Built With One Tool and No Fasteners

Above, the Shopbot shed from the Maker Faire in Austin, Texas.

OK, you have a blank sheet of paper and a pencil. Your challenge is to design a house or structure using 4×8 sheets of plywood without driving a nail or screw. Oh, yeah, did I mention no glue either?

A recently closed exhibit at the Museum of Modern Art in New York showed just how to do it, thanks to the efforts of the architecture and engineering colleges at the Massachusetts Institute of Technology (MIT). You can watch a short video of the New Orleans House being assembled (click on the arrow in the lower right corner of the video player to advance to “Housing for New Orleans”). It took three MIT students just a few days to assemble the 20′ x 40′ one-story house that’s part of the Museum’s exhibit “Modern Dwellings: 5 Contemporary Pre-Fab Houses.”

How does it work? Instead of stud walls, lengths of plywood strips lock together in an “egg crate” fashion. The exterior plywood edges have “tabs” milled into them so exterior sheets of plywood with corresponding “slots” are applied as a “skin” which, in effect, produces a torsion box. Where plywood sheets butted together, a series of joints not unlike an interlocking puzzle pieces were used.

All this precision cutting of a few hundred sheets of plywood was done using a Shopbot Buddy 48 CNC system. All the parts, according to Ted Hall, president of Shopbot, were then tapped together using a rubber mallet. He added that New York officials insisted all the parts be glued, although that wasn’t necessary to create an extremely rigid structure. In fact, he said, after testing MIT engineers and architects concluded the amount of plywood used could have been reduced by half or more and still provide sufficient strength. The New Orleans House was rated to carry a load of up to 250 people and used more than 500 sheets of plywood.

Why so much plywood? Hall said the MIT plan called for parts to be cut and delivered to the MOMA site in the sequential order of assembly. The material was not cut for optimized yield, which led to more waste, Hall explained.

Another example of the construction method was employed in a shed structure Shopbot produced for Austin, Texas “Maker Faire,” where the company was awarded two blue ribbons from the editors of Make magazine , one ribbon for the shed and one for Shopbot Buddy 48 CNC machine. This kind of shed is today a more practical application of the building method because local building officials usually don’t require permits for smaller structures and getting them to approve a new construction method is often problematic, Hall explained.

For MIT, the objectives of the design were to use locally available materials to produce a structure that could be erected quickly using parts either made on-site or near-by and require a minimum amount of labor and minimal construction skills. Using good design and engineering “digital cutting techniques put the smarts in the parts,” Hall said. Then, just about anyone could knock together a shed using only a rubber mallet.

Will such building methods catch on? Hall said he hopes to introduce the technique to backyards all over the United States with simple shed designs. And farther into the future? Hall said he dreams one day a customer could walk into a “Kinko’s” type business, browse some catalogs, choose a design for not only a shed but kitchen cabinets or coffee tables, then have the parts cut out in the back room on a CNC machine for home assembly.

– Steve Shanesy, Publisher