So the first thing to do, now that the roof is put on, is to build a floor. We decided to insulate the whole outer shell, so we have to space the load-bearing portion of the floor up off the corrugated metal subfloor to make space. We’ll use 3/4″ and 1/2″ plywood as the structural materials here, with foam insulation sheets cut to fit between the floor supports.
With about twenty 48″ support strips cut out of 3/4″ plywood, the job boils down to chopping them to various lengths to fit them to the van floor. I sketched out a schematic ahead of time, to get an estimate of how much plywood I would need and make sure the unsupported spans would all be acceptable. I want a nice firm floor that doesn’t bend underfoot; the L/360 span rating for the plywood I’ll be using is 12″, so anywhere a span exceeded that length, I added additional bracing near the center of the span to avoid any sagging.
We’re using Gorilla Glue to fix the joists to the van floor, so they need to be weighed or clamped down after placement for the glue to cure strongly. We used a low-tech solution:
We also want to ensure the floor is relatively flat. The metal floor corrugations vary somewhat in height and some corners don’t have them at all, so I glued together wood shims to the height I needed to use as spacers.
Once that’s all figured out, you start at one end and lather, rinse, repeat until you get to the finish line.
We also took this opportunity to spray some rust inhibitor on the steel floor and seal up any possible future leaks at sheet metal seams, welds, etc. with silicone caulk. This will be the last time the subfloor is easily accessible, so it’s now or never.
The next posts in this series will cover insulating and finishing the plywood floor, then adding the final vinyl tile covering, as well as building a shower pan. Then we’ll move on to plumbing, wiring, walls and built-ins.
Finally, a PSA:
See you soon!