Computerizing and automating home panelization
Tedd Benson has “only a small ambition,” he told assembled guests at the grand opening of his Unity Homes factory in Keene, N.H., in 2018. “We intend to change the building industry. Dramatically.”
Benson’s roots as a builder go back to the 1970s, when he helped to kick-start the timber-framing revival in the U.S. with his classic book, Building the Timber Frame House. But the vision has evolved over the years, and Benson’s current venture, Unity Homes, is about much more than honing a chisel.
In July 2018, JLC toured Unity’s factory in Keene, N.H. What we saw was a state-of-the-art computerized and automated facility where comprehensive CAD plans are turned into complete high-performance custom home packages that the company’s trained crews can erect on site in a matter of days.
In December, we went on site in Brewster, Mass., to see a crew set one of Unity’s house packages. What follows is a look at both ends of the process: the precise factory fabrication of house components in the Keene facility, and the quick erection of the home on site in the field.
The company’s goals are ambitious and broad: building in a few weeks homes that can last for hundreds of years; precisely controlling fabrication to eliminate construction defects completely; and creating a process that can scale up to become standard practice throughout the nation. Can they do it? Read on.
Touring the Unity Homes Factory Floor
Humans have dreamed for years of a future where all the work would be done by machines. At the Keene, N.H., manufacturing plant of Unity Homes and Bensonwood, that future is one step closer to becoming a reality. The plant cranks out complete home frames, bundled for assembly on site, including walls, roofs, and floors. There’s still plenty of work in the facility for people. But much of the fabrication, along with all of the heavy lifting, is done by high-precision machinery (see photos). On a tour of the facility, JLCgot to see some of the equipment in action as Hans Porschitz, Unity’s chief operations officer, explained the setup.
At the heart of the operation is a Hundegger Speed Cut SC3, a versatile robot that gets its instruction directly from a home’s CAD design file. Workers load the machine with raw materials using a vacuum-lift crane. The Speed Cut can handle solid beams as fat as 7 inches by 24 inches and has no trouble with wood I-joists or glue-laminated stock. Inside the machine, a spinning saw blade makes all the necessary cuts for stud, joist, and rafter framing. Routers can hog out mortises and tenons or holes for chases. Cuts are precise to 1/16 inch. And the Speed Cut’s ink-jet printer not only labels every part that’s cut, it also handles layout for wall, floor, and roof panel assembly. Workers who put the components together rarely have to touch even a tape measure or pencil.
From the Hundegger, parts are bundled and carried by forklift to three parallel assembly lines: one for walls, one for roofs, and one for the “open cavity” components (interior walls and floors). During assembly work, operators don’t have to bend over or lift heavy weights, because machines handle the lifting. And operators seldom touch a tool; they just place parts on the framing table. Machines nail studs to wall plates. Workers do have to tack sheathing in place (although they don’t have to lift it), but automated routers handle the sheathing cuts, and rack-mounted nail guns nail the material off with precision accuracy.
Built in a Factory, Assembled on Site
The first sign that assembly of the house was imminent was the far-off sound of a semi truck winding its way down a narrow dirt road through the woods on Cape Cod. The Unity Homes crew had arrived from New Hampshire a day earlier and set mudsills on the foundation. The crane—an absolutely essential part of the assembly operation—was set up and ready. What followed over the next five days was nothing short of incredible to observe.
Crew coordination. The crew of four from Unity Homes worked together like a well-oiled machine. These guys had assembled many Unity homes together. In addition, they alternated their time on assembly crews with time in the factory, so they were able to bring valuable feedback from the field to the factory floor.
Whether unstrapping a load from a trailer, rigging panels for lifting, or nestling a panel into place on the house, they worked quickly, efficiently, and methodically. Every crew member seemed to have a good idea of what was supposed to be done next.
Safety first.It would be easy for an experienced crew to get lax with safety on the jobsite. But these crew members always wore hard hats during crane operations, and their bright yellow shirts were much more for jobsite visibility than for promotion.
Fall protection equipment was used at all times while the roof panels were being set. The lifting-strap anchors on the roof panels worked perfectly as attachment points for the equipment. And the panels even came from the factory with toe boards attached.
Attention to detail.Perhaps the most impressive thing was the crew’s attention to detail when it came to air-sealing the panels. Specialized gaskets were used to seal every connection between the subfloor, walls, and roof panels. They meticulously executed every detail with a complete battery of different tapes and sealants.
Original Story By: The Journal of Light Construction