So my little teardrop trailer plans have changed into a 12'x6' camper so that I can stand in it. I'm in the planning phase still. What I'm doing for the walls is 3 layers; an outer 1/2" board, a middle 3/4" board with cutouts for foam insulation (also for weight reduction) and a 1/8" inner finishing board.
The top roof will be plywood until right before the curve down towards the front. From there it'll be aluminum all the way down.
My concern is if I'm making the back strong enough.
Here's what it looks like
The roof will also have a sandwich design like the walls, but it'll be 1/2" outer, 1/2" structural and hollowed out middle with insulation, and 1/8" finishing inner. I'm planning on laying the middle structural ceiling on top of the inner walls, which will make it flush with the top of the outer walls. Then put the outer roof panel on top of everything including the outer walls. I'm hoping the outer roof board being on top of the outer walls will also help with water issues.
Does this sound right? Or should the outer roof panel be in between the outer walls and just make sure it's good and waterproof? I also have a concern regarding the walls.
The walls for the camper will be a sandwich of 3 layers. I'm using all 4'x8' plywood sheets.
See the image below for my design and then I'll explain.
I made everything 2-tones so that you can see the different board of plywood easier. The blue colored panels are the outer 1/2" plywood boards. The green ones are the inner 3/4" plywood boards that I've made cutouts in to reduce weight (and I'll be filling the voids with insulation). There will be another nicer layer of 1/8" plywood for the interior.
What I've done is arranged all the boards to be standing upright, and I offset them so that the inner and outer boards don't have seams in the same places. The outer is just three 4' wide boards. The inner is 1' wide on the left, then two 4' wide boards, and then a 3' board.
So my question is; If the 2 layers are glued and fastened together, does this seem like it'll be quite strong? I was going to screw them together, but does someone recommend another method? Maybe bolts and t-nuts and glue? Should I add some blocks where the green boards meet to further fasten them together? Or should I just do pocket screws?
Keep in mind this will be on a trailer and moving around. I want it to be nice and solid, and hopefully last a long time. This is why I'm seeking out advice.
The roof won't have anything on top of it other than a vent with a fan, so I'm not worried about it being able to carry any weight other than itself.
Here's an update to what I have so far with framing the roof:
The small blue square on top will be the roof vent with fan. The large blue rectangle in front will be a front window. The framing around the vent are 2x2's. The 7 others in front are all 2x4's. I'm not sure if the 2x4's are overkill, but the front half of the trailer won't have a heavy-duty roof. It'll just be a couple of thin layers of plywood that I can bend down the front, finished off with some 0.05 aluminum on top.
Extra pics to show layout for possible balance issues. Front will be a queen-sized bed. Left rear-corner is a table with 2 chairs. Right-rear corner will have a large cabinet with the bottom-half of the cabinet reserved for a sink that will slide outside. The water tank and extra storage will be under the bed.