STARTING YOUR BUS BUILD
The beginning is the most daunting part.
You have an empty space and you can turn it into anything you want. Literally however you want it to be. Yes, building out your rig can be empowering, but it can also be overwhelming. If you do not have the carpentry, plumbing, mechanical, or electrical experience knowing what to tackle first can add a lot of time to the build.
I found my bus on Craigslist, from a guy who had been living in the parking lot of his work, to save on travel expenses. He was not a carpenter by any means, so the build was very simple. The bus was full of expensive items crudely build into a semi livable space. The photos below are how he clad his walls, floor, and ceiling. The bottom right is how I framed and insulated the walls.
For any future builds, I will not buy something partially converted by another person. The electrical from the bus had been modified in weird ways. I also trusted his subfloor, which I found out later was not level from his spray foam job. This caused a lot of headache in my furniture build because of high corners.
TEAR DOWN
Start by gutting the bus. There is insulation in the walls from the original build, but it is thin and not meant to help at the level you want for living, so I suggest stripping it and using your own. Many people coat the floor and walls (pre insulation) with a rustoleum paint to help seal all the metal. My bus was already sealed, but this is a good step, particularly if you plan on traveling in different climates. There are a lot of options for insulation which deserves a post of its own, so I won't delve into that, but whatever you choose it's the next step in your process.
I see a lot of people use full 2x4 wood on the walls for framing (previous owner included if you look at the photos), which eats into a lot of your space and materials. Unless you plan on using 1.5" foam in all the walls, you can go with something much thinner, and you can definitely have the material be less than 3.5" wide. The framing has two purposes: something to attach whatever you skin your walls with, and added depth for the insulation. If you plan on tying your furniture into the walls, then you want to mark where the framing is so you hit material. I milled my pine down to 1.5"x1.5" because I reused the rockwool insulation that was installed by the previous owner. I would not used it by choice because of the itch factor, but the price was right. Ideally this wood is treated so it doesn't absorb moisture. Make sure to back paint too, because you want all edges sealed. Now you need to skin your walls. I used lauan, which is a 1/4" sheet good. It is different than 1/4" ply because it only have the outer layers and a core, vs plywood with multiple layers. I did not need it to be pretty or structural because I planned on having very little open wall space. I used a different material over the lauan to be my wall in the front of the bus.
Electrical is the next step you want to take, along with plumbing. It is much easier to frame out where your water tank is going to be and cut holes for water inlet, shore power, etc when you don't have furniture in the way. I had all my electrical wiring run above the windows with the existing wiring, as there was a channel for it. This kept my walls clear of any wires until they got to my battery bank. If the bus had a system, it is likely that someone engineered it that way for a reason, so I work with what the bus gave me. I chose where the ceiling lights would be and ran wires to those points, knowing I would not wire them up until installing the ceiling panels.
