This weekend, we're ready to install the subfloor. First, I'm adding a layer of epoxy and sill insulation (not pictured) to strips of plywood that will support the areas where the pieces of subfloor butt together. The frame's cross-members are slightly lower in these areas to accommodate these supports.
Here are all our subfloor pieces with a layer of Reflectix insulation lightly glued to the underside. Reflectix is basically heavy-duty bubble wrap with a radiant heat barrier on either side.
There's a lot of debate in RV forums about whether this stuff is worth the money. The r-value of bubble foam is minimal, about an R-1.1 for the 5/16" layer. But r-value is about resistance to conductive heat, and that's not what this stuff is for. This layer is to reflect radiant heat back where it came from. So when we're parked on a hot parking pad, or when the wood stove is cranking out heat, this stuff is to keep as much of that heat as possible from radiating (not conducting) through the floor.
Granted, I'm going to benefit a little from the R-1.1 resisting heat movement from the subfloor to the steel frame members by conduction. But to reflect radiant heat, the Reflectix needs to be facing an air space. I've only lightly glued the Reflectix in place, so once this is installed, it will pull away from the subfloor a bit and make a pocket of air under the subfloor, which should help reflect heat back to the subfloor. I'll be packing the bellypan with Rockwool insulation, but I expect that the Rockwool will settle over time and pull away from the subfloor, creating another air space just below the Reflectix, which will help reflect heat back to the exterior of the coach.
Worth the money? Let's just say that 200 square feet of anything just doesn't cost that much. Anything I can do to improve the insulation in our tiny house even a little should pay off big down the road.
Subfloor is in place, ready to be bolted down. If you look carefully at the rear of the coach, you can see that I covered the edge of the last piece of subfloor with something. That's a product called Protecto Wrap, which is a butyl membrane made for sealing around a rough opening of a window in a house.
Airstreams have a huge problem with water penetrating the rear bumper area and rotting out the floor. The cause is a silly design decision, which basically funnels water from the rear bumper lid directly under the plywood subfloor. So, in addition to encasing my subfloor in West System marine epoxy, and not reinstalling the bumper lid in the factory Rot-o-Matic (TM) manner, I'm using the Protecto Wrap to prevent water from reaching the wood from the bumper area.
The Protecto Wrap laps underneath of the Reflectix below the subfloor, so any water should end up in the bellypan and eventually drain to the ground. I've left myself enough Protecto Wrap on top of the subfloor to lift it up inside the c-channel (between the interior skin and the c-channel) to create a dam that should help keep water from entering the coach.
Leanne did an excellent job at trusting me not to drill her feet while I installed the elevator bolts.
At this point, the shell is resting entirely on the frame. Note the orange straps hanging loose. That gap between the floor and the rear of the shell is normal. The steel frame flexes so much on its own that you have to jack it up to meet the shell.
Sometimes there just aren't enough hours in the day.