SURE Construction: 02 Floor Framing

-- We are excited to have started building the SURE HOUSE in a parking lot on the campus of Stevens Institute of Technology in Hoboken New Jersey. “SURE Construction” is a subset of our PopSci blog that we’ll use to chronicle our construction process. Check back often if you want to follow our progress and get a first hand view of how a sustainable and resilient house takes shape.

The 'Foundation' for Resiliency
SURE stands for sustainable and resilient. The core of our approach to sustainability is a high performance building envelope that allows the house to maintain interior comfort using very little energy. Our focus in resilience is storm and flooding protection. Combining these strategies in the construction of a house that also needs to be taken apart, shipped across the country, and then quickly re-erected creates unique challenges at every phase. Framing our floor was really the beginning of this dance.
Plastic
SURE HOUSE is wrapped in a layer of floodproofing. We started floor construction in the shop where we adhered sheets of ABS plastic to tongue and groove floor sheathing…
Plastic + OSB (Oriented Strand Board)
...creating a laminated flood resistant sheathing of our own design.
Attachment to Foundation
We then set these sheets onto our temporary foundation and attached the floor framing through the OSB portion of the laminated sheathing.
Minimized Penetrations
This allowed us to minimize the penetrations in the floodproofing under our floor.
Framing Complexity
The floor framing itself was typical but somewhat complex. Here you can see a dropdown in the framing to allow our large southern lift and slide glass doors to have thresholds flush with the finish floor. The box framed into the I-joists and section of LVL framing has to do with our plumbing runs and awesome walk-through shower floor.
Modular Considerations
Since we are capping the bottom of our floor framing, our floor system is a four-sided box. That meant that we need to insulate before installing the floor deck, not a typical construction sequence. Also, since we are building the SURE HOUSE in three separate modules for shipping, each with its individual framing package, we needed to insulate and sheathe each module separately. This required tight coordination between framing and insulation. Here, the first module floor frame has been completed and the second is being insulated just as framing is finishing.
Floor Insulation
We have designed a vapor-open, floodproof wall and floor assembly (more details on that in an upcoming blog) that utilizes ROXUL stone wool insulation. We installed batts between the I-joists…
No Cavity Unfilled
….carefully filling all smaller cavities.
High Performance Considerations
High performance is all about the details. To get the R-30 we needed in the floor to meet our performance specs established through computer modeling, we didn’t need to fill the whole cavity, but we had to make sure the edges of the framing were insulated to reduce thermal bridging (essentially places where insulation is broken by a material with a higher thermal conductivity). We cut strips of ComfortBatt and pinned them to the perimeter floor beam with a plywood washer.
Completed Floor Insulation
The second floor module with insulation completed.
Air Sealing for Efficiency
Our approach to sustainability hinges upon reducing energy usage by creating a highly insulated, airtight building envelope. In our floor, the interior deck sheathing is our air barrier, the zone where air from outside is prevented from entering the house. This means we have to seal all the sheathing joints. For this purpose, we used an incredible vapor permeable tape from Pro Clima, Tescon Vana…
SURE Seal of Approval
This stuff is really strong and once it’s down it stays down and seals completely. So much so that in our case we were also able to use it as a temporary water seal while our floor was exposed to rain before getting under roof. We got some rain and it worked great!
Completed Floor Modules
Here, we’ve finished the first two modules. The subfloor sections with the orange spray paint are panels that weren’t glued in place so that we could take them up to either access (1) the bolts holding modules together or (2) plumbing and electrical penetrations through the floor frame.
Next Up...
Framing the walls with wood and steel.