Wall and Floor attachment to trailer?

[Campin' Texan]

I have a 5x10 trailer that is currently being welded together. I'm getting my plans together to attach the floor to the trailer. I've seen this illustration on the different methods of attachment to the frame:



My plan is to use the simple Lap Joint. My question is, what would be the problem of leaving out the 2x2s under the floor? Would I run into any problems by bolting the floor and the walls directly to the metal trailer frame?


Thanks

[Armed Patriot]

the 2 x 2 sub floor frame is to give you something to screw your sides to.

[Campin' Texan]

the 2 x 2 sub floor frame is to give you something to screw your sides to.

What would be the issue of attaching the wall directly to the metal trailer frame? Like this:

[48Rob]

Shouldn't be any issues if you use self tapping metal screws.
I would be more comfortable with a few bolts though, in addition to the screws were it mine.
Screws are strong, but brittle if put under too much strain.
A bolt may bend a little in this application (in an accident, etc.) but will keep the trailer together.

Rob

[pohukai]

In my design, I use only the existing holes in the frame. Drilling through the frame *might* weaken the main structure the trailer designers did not have in mind. So, that being said, I use a wood frame, mounted to the trailer. The walls are attached to the wood frame with screws and glue. A few new holes may be ok, but I'm just super paranoid since 'how many new holes in the frame is too many?" or just one, the wrong size in the wrong place could result in an ugly situation if you don't do a finite element analysishttp://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/num/widas/history.html. (I not that interested)

Jim

[mallymal]

I'm still scheming & dreaming but if my OH ever lets me build I'd go for the rabbet joint, and would bolt through the wall into the metal chassis, using a large headed bolt, so there would never be any chance of pull through. With this type of fixing, it's great for recessing the head too:
http://www.screwfix.com/p/cross-dowel-bolt-m6-x-50mm-pack-of-50/78664#.
This is a UK based company, but I'm sure you have something even better across the pond. BTW they're called dowell bolts here.