For my Arborion design Tiny Home I’ve chosen the 8′ 6″ x 20′ utility trailer built by Tiny Home Builders as my foundation. After spending many months searching CraigsList and trailer manufacturer sites, I am sold on this sturdy design and reasonable pricing. I should also mention that my design calls for some slight modifications to their standard trailer. These modifications include wider trailer deck flanges along with reinforcement on the sides and two welded, threaded rods on the front and rear of the trailer frame to account for lack of flange to bolt through.
The layers of the subfloor consist of the following layers from the ground up:
- Metal framing support of the trailer. By selecting the trailer I described above, I start with an ideal platform to build a well-supported and strong subfloor.
- 1/2″ plywood painted, sealed or covered with aluminum flashing on the underside. The five plywood sheets will run across the width of the trailer.
- A framework of 2″ x 1-1/2″ supports ripped down from 2x4s. Double joists will be added at the plywood seams for better attachment and support. This will allow just enough vertical space for the insulation, plenty of support on top of the metal framework of the trailer, and saves vertical space within the home. Also, all plumbing and electrical will be run through the walls so no extra space is needed within the subfloor for these components.
- 2″ ridged insulation panels with foil backing on both sides for blocking infrared. I have yet to determine the brand I will be using. Although this is not a ‘green’ option, nor is it cheap. I feel that with the life-span of the home and the energy savings of this high-efficiency energy barrier, that responsible use of this product will be worth the investment.
- Five sheets of 3/4″ plywood run along the length of the trailer (across the joists). The exception to this is the middle sheet of plywood will run across the width of the trailer.
The top side of the finished subfloor showing orientation of final layer of 3/4″ plywood, as represented by a 1/8 scale model. Note cut outs for the trailer wheel wells.
The underside of the subfloor with partial layering of aluminum flashing, 1/2″ plywood, and subsequent layers as represented by a 1/8 scale model.The underside of the subfloor, minus the initial flashing and layer of 1/2″ plywood, as represented by a 1/8 scale model. The silver panel between two joists represents the insulation that will be used throughout the home. Note that the cut out for porch has finally been added and is separate from the subflooring and will be attached directly to the trailer. This will allow for better drainage during wet weather and protect the home (main subflooring) from possible water damage.
The attachment of the subfloor to the trailer will consist of five 1/2″ dia. bolts along each long side of the trailer securing everything to the flanges. While the front and the back will be attached via two welded, threaded rods since there is no flange here to bolt through.
Cross section of subflooring attachment to trailer flange via 1/2″ dia. bolts.
Next up – Scale Model: Exterior Walls