Orchestrating the Dance
Just as Unity has developed sophisticated systems for fabricating the components of a project in our production facility, we have efficient, highly-evolved processes for assembling these components on site into the shells of high performance homes. The two phases of a project are complementary and integrated. In fact, the same team members who build the panels in our shop assemble them on site. Working this way has many advantages, including facilitating feedback between the field and shop about what’s working well and where we could improve.
We typically send a crew of two or three for assembling shells on site, and we augment this core with a couple of local carpenters. In addition to reducing costs, our hiring local tradespeople gives them experience working with our systems, and a sense of ownership of the end result. Our crews are well-trained in site safety procedures, and we provide training for any carpenters working with us.
The work of our crews on site is carefully planned and orchestrated. The site schedule is broken down by the hour: which panels will be picked, and who’s doing what. Because the details for installing and fastening our panels are standardized, the assembly can happen with minimal reference to the plans. And our crews always have the fully-elaborated 3D model available on a laptop to reference as needed.
We will have scoped out the site ahead of the delivery of panels, to ensure appropriate access for the delivery trucks, and space for staging and the crane. Ideally the foundation will be backfilled, and temporary power will be available on site. We’ll arrange for having a boom forklift on site, and we hire the crane.
When the trucks arrive with the panel bundles, they are unloaded with the forklift and staged where the panels can be picked by the crane. The first panels to “fly” will depend on the foundation type—walkout, full basement walls or slab.
If the home is built on a slope with a walkout (“daylight”) basement, we will have taken field measurements of the completed foundation to accurately fabricate the walkout walls. Once these are installed, we place the columns and beams that support the first floor, and fly those panels. Then it’s on to the first floor wall panels, which is where we start if we are building on a slab foundation. If the design includes interior bearing timbers to support the second floor or roof, they will be installed in conjunction with the panels. If the house has a second floor, those floor and wall panels will be installed once the first floor walls are up.
We fasten joints between panels with long screws, and air seal them with a combination of gaskets and specialty tapes. Any hold down hardware specified by Unity’s engineers will be secured to the foundation and framing.
Unity offers two basic options for roof framing, both of which are set with the crane: truss roofs, and roofs constructed of insulated panels. Truss roofs are more economical, whereas insulated panel roofs allow for more conditioned space – and vaulted ceilings – within the house.
Completing the Shell
Once the basic shell of the home is assembled, the Unity crew installs any additional exterior elements such as deck framing, screen porch structures or timber brackets for roofs over doors. When our crew’s work on site is nearing completion, the job captain does a walk-through with the client and local builder to confirm the quality of the work, and any tasks that remain to be completed. Our crew leaves the site clean and orderly, ready for the Post Assembly phase to begin.
If Unity is providing Whole House services, then we’ll continue to be responsible for all work on site through to completion of the home. If the client has elected a Shell or Tempo package, then the local builder will take over the work on site, once our crew has finished assembling the shell.
Roe Osborn, Senior Editor, Journal of Light Construction
What followed over the next five days was nothing short of incredible to observe.