Sub-Floor Framing Fiasco
I had originally planned to build my floor on 2"x2" framing, but discovered they wouldn't line up with the bolt holes already existing in the trailer frame. Not wanting to add too many new holes to the trailer, I next considered 1"x3" framing. Unfortunately, although they would allow use of most existing bolt holes, I realized I needed to countersink my bolts or they would interfere with the placement of my walls. <Sigh!!!!>
So... I finally settled on a combination of 2"x2" and 2"x3" framing, with additional supports added to compensate for the use of 5/8" plywood for the flooring. This will provide more "meat" for the walls to attached to, but also means updating my build plans to compensate for the difference in wood thickness.
I used 3/8" bolts and 1" washers countersunk into the wood framing and lock washers and nuts to secure the entire sub-floor assembly to the trailer. I also used self-tapping screws where bolts were not possible.
My floor will be attached to the framing with 1.25" screws and will consist of two pieces, seamed up the middle of the trailer.
Countersunk bolts/washers & self-tapping screws:
Side profile of the sub-floor framing:
While framing the sub-floor, it became evident the trailer frame is slightly off square and is about 1/4" longer on one side. This will be hidden using a wooden bumper/fender once the build is near completion.