First, some photos of the exterior to give you an idea of where it’s at at this point.

Here is the insulated floor.  It’s pretty self-explanatory, so I didn’t really make a how-to documenting how this was done.  Basically, I cut the 1/2 inch “rigid” foam insulation to sizes that fit where they need to go.  I pretty much just freestyled the cutting because if something didn’t fit quite right, a couple of razor cuts made it fit perfectly.  Then, I just glued it all down using the same 3m 90 adhesive that I used for the ceiling.  It took maybe an hour.

I picked up the sub-floor wood from Dunn Lumber.  It’s 8’x4’x3/4″ plywood with a tongue and groove edge.  I chose plywood over OSB because this floor will also act as an anchor for my studs and other things that will be screwed to it.  OSB is cheap, but can’t be used like that.  I believe that this should also make framing out the walls under the sub-floor unnecessary.  I see other projects that do that, putting the insulation between the frames, then setting the subfloor on top of that.  It just seems like a lot of work for little payoff.  Plus, it’s hard to keep the thickness down.  I need as much headroom as I can get since I am not raising my roof.  As long as my sub-floor is attached well with adhesive, and all connected together, it should be a solid foundation for the interior build.

The first board will go on the back.  Eric helps make measurements.  Also pictured is the 3m 90 strength spray adhesive we will be using.

Perfect width.

Eric temporarily pulls up the subfloor which has not yet been adhered to the floor to make an adjustment.  This is a good photo of all the layers of my floor.  Note also, the foil-faced, moisture resistant insulation should act as a decent vapor barrier.  The process goes like this:

1. Spray adhesive between the insulation and the metal floor, lay that flat.
2. Line up the sub-floor tongue and grooves, but don’t marry them yet.
3. Spray the glue between the insulation and subfloor, then lay the wood down.
4. Use a scrap piece of wood and a 4 lb hammer to knock the tongue and groove slots together.
5. Walk all over it to help the glue adhere to what it needs to adhere to.

We measured the floor, cut the pieces in the basement using a circular saw.  A jig saw was used for some of the tricky corners, like the curves around the wheel wells.

In the foreground you can see the scrap wood and the hammer used to knock the wood together and marry the tongue and groove joints.  Using the scrap wood between your hammer and the sub-floor pieces saves the tongue and groove from damage by disbursing the force of each knock.

The weird thin spot by the rear side door is held down with the weight of this gas canister to be sure it adheres properly.  When the side studs go in, it will also help with holding everything down.

Done with the floor!

The beginning of the side studs.  Each bus rib will get a 2×4 that will act as a stud for the rest of the build out.

Studs on the right are installed.  The left side is next.

Ralphie likes the bus just the way it is.

The studs are mostly installed.  The studs over the wheel wells are not yet attached.  They will be last.