How We Tiled In An Airstream
We did a post a few months back about searching for the right tile, and what tile material/size to stick with. Ultimately when it comes to tiling, it's all about ensuring movement and flexibility, so that when you pull away from the curb your heavy, stiff tile doesn't begin to crack.
We used 1" ceramic hexagons in the kitchen backsplash. In the bathroom we went with 1" blue pennies for the floor space, and 1" glass squares for portions of the wall. To begin in the bathroom, we framed out the shower with 2x4s. We built the frame so that it moves independently from the shell, as one unit, to help minimize the movement in the tile when the airstream is on the move. We then attached wedi board to the framing. Wedi board is a foam core, waterproof tile backing; it's lighter in weight than hardibacker, and it's waterproof. On the floor, we used Red Gard Uncoupling Mat, it is also waterproof and designed to provide a buffer between movement of the floor and the tile, creating more flexibility and mobility through the floor tile. Ideally, this mat will help to isolate the tile from the floor a bit.
To adhere the backsplash to the aluminum in the kitchen, we used a PL Construction Adhesive followed by grout.
Finding a flexible grout was a bit tricky, we used Tec AccuColor Unsanded Grout and instead of mixing it with water, we mixed it with Tec Acrylic Grout Additive for increase flexibility in our grout. You'll want a pretty thick consistency for best results, not a drippy texture. If the mixture is too wet, you may experience little air bubbles as you begin to spread it.
A few things we learned: be sure to get the grout as perfect as you can get it, because if you attempt to touch it up the following day and have to mix new grout, the color of your grout can vary between batches. Also, working with thin tile will make your life much easier!