Two weekends ago I walked into our Airstream shell and felt sick with dread--what to do next? Peter popped a cover on the broken skylight and propped the back belly pan into place, and then he suggested we go buy subfloor supplies. I so admire that my guy is a doer.
When cutting out the subfloor last fall, he had left a narrow strip of plywood in the c-channel to prevent collapse, so while he worked on cutting the bolts to free those pieces (combo of a multitool and a diamond blade), I vacuumed out the grime and leaves that had accumulated during the winter, and started applying sealant (DAP polyurethane) to any little screw holes in the belly pan. We are attempting to go all-electric, so I also used aluminum tape to cover the propane holes. Water-tight for now, but easy access if we change our minds.
Peter successfully extracted the front curve of the subfloor intact, so he was able to use this to trace the cuts without having to do any scribing. We used Dryply sheets that were slightly thinner plywood (I believe the original was 5/8, and we used 23/32) and I could not believe how easily it slid in. Peter did do a little banging into place, while I pushed on the c-channel from the outside, but after the horror stories we had read about shell-on subfloor replacements, we were both pleasantly surprised.
I noticed a lot of people do the front all one piece, running the boards side to side instead of end to end. Doubtless there is a good reason for this, but we felt there was more rigidity and structure in using 6 pieces long-wise, and we used 1/2 plywood the reinforce the seams. For the back of the Airstream and for the side bath, we chose pressure-treated plywood in hopes that this will stand up better to any water exposure than the Dryply might. Peter also sprayed the edges with Flexseal. We put 3.5" mineral wool insulation below the floor. We also ran a conduit pipe from the area of the fresh water tank to the black water tank, just in case we decide to run any pipes or wires through the floor, we will be able to access either end even with the floor on.
We did hit a bump with the screws. Since we were doing this shell-on, bolts were not an option, except in front of the door. The 1/4 stainless steel screws we had purchased kept breaking, even with meticulous pre-drilling and we were momentarily stumped. Turns out there are these 1/4 wood-to-metal self-drilling screws that are, unsurprisingly, called trailer screws. We got two kinds, 2 3/4 and 3"--the former worked much better, whereas the 3" needed a little pre-drilling. Those joined the c-channel and frame, and subfloor and frame, and we used wood screws on the seams and additional stability in the c-channel.
The back curbside (right) subfloor installation was the worst because (1) Peter cut a slot for the black tank dump valve, which did not give us a lot of wiggle room to bang the floor into the c-channel without misaligning that slot, and (2) the c-channel had collapsed a bit AND pulled away from the skin, in part due to an accident that side apparently sustained, and in part due to wood rot near the hot water heater. Peter ended up shaving the bottom edge to give it a thinner, gradual edge, and I used a screwdriver to wedge the c-channel open while he banged it into place.
While subfloor installation was underway, a few other things were addressed: we did our first rivets! We patched the hot water heater hole and ended up adjusting the belly wrap on that back corner, inadvertently banging a dent out. We also reattached the back belly pan and built a platform for the black tank to rest on. (No idea how it used to fit in there, did it really just rest on the two bars across the back frame???) It was pouring rain outside one of our work days, so we were able to find and patch a few leaks--though I have been extremely pleased with how water tight the outside shell has remained all these years!
Memorial Day was rough because Peter's back was in bad shape, so once one half of the back was screwed into place, we called it a day and will put in the last piece next weekend. This decision also allowed us to delay figuring out what to do about the bird who built a nest in the interior of the old A/C unit. She still has access to her babies through the back belly pan, but that access will be gone when the last of the subfloor is in. We think the birdies will be old enough to leave the nest by then, but we will see.
Our next priority will probably be electric and A/C installation so we can continue interior work without suffocating as the weather warms up. Sorry, no photos here! For visuals of the process check out @rhody_airsteam on Insta.
