I’ve added the last layer of insulation.  It took a while, but we got there.  If I had to do this again, I might consider doing it a different way.  This method required a lot of time and touch-ups.  The spray insulation that filled in the gaps between beams and insulation was not very cooperative on the ceiling, where it tended to drip on the floor, and required a few layers to work effectively.

A freaking mess.  You can see some spray foam insulation coming through the rivet holes of the arch beams in the rear.  That was an experiment.  I did ultimately inject insulation into the beams, but I’m not sure how much help that will be.  At the very least, it might help with preventing future leaks.

Julene is helping with some “rigid” foam…

Here you can see one of the cross beams that sit between the arching ceiling beams.  They’re made of a bent piece of steel, I believe.  I filled the void created by the bend in the piece with rigid insulation, then covered it with reflective aluminum tape.

Here’s another angle showing the insulated support beams.

The big voids along the bus that sit just above the windows are used as a space to run the wires for the running lights.  I intend to use this space for other wire runs, but I won’t need the void space. Therefore, we used 1 inch rigid foam to fill the gaps.  I just cut pieces that fit and Julene popped them in place.  They are extremely snug.  I then used spray foam to hold them in on the ends where they almost touch the rounded beams.  There were bolt heads there that made it difficult to fit the rigid pieces precisely, but the spray foam sealed it perfectly.

This is one of the final interior layers of recycled denim unsulation, prior to spraying the gaps on either side, near the curved beams.  Also, you can see that the void directly below this sheet is filled with spray foam.   I thought I might do this for the length of the bus, but found that using the rigid insulation and sealing it with spray foam would be less labor intensive, and more cost effective.

On the let are two layers of insulation (Foil faced recycled denim insulation with the reflective side facing the exterior/Half-inch rigid foam insulation with the reflective side facing inward).  The rigid foam holds the outer layer snug to the exterior.  On the right of the beam, you see the third added layer of recycled denim with the foil facing the interior.

I cobbled the rear insulation together with scraps.  It was pretty easy.  I needed to allow space for wires to pass through, so this was faster than cutting a big piece to size and poking holes in it.

Workshop.

Final interior layer not yet installed on the ceiling.

There was a lot of cutting involved.

After the final layer of insulation was glued into place with contact cement, I sprayed the spray insulation in the gaps, let it dry, and cut away the stalactites of insulation that formed as it expanded and cured.

With the gaps insulatied, I covered the spray foam with aluminum foil insulation to create one uniform radiant/vapor barrier inside the bus.

Eventually I cleaned up my huge mess.

And primed the floor with rusty metal primer.

I went back and painted those wheel wells after the first coat dried.  I also sprayed the rear stairs with truck-bed liner for extra super protection.