How To Build A Teardrop Trailer/Assembling the Body
Attaching the Sidewalls
The sidewalls will sit on the trailer frame and will be bonded to the wooden bed that is already bolted to the frame. Polyurethane glue is used to glue the sidewalls to the bed. Some builders use wood screws mainly to hold the sidewall while it dries.
However, the polyurethane glue, as good as it is, is really only gluing the top ply of the plywood. It is unlikely the glue will fail, but the plywood could fail. It does not take that much force to strip the top ply off of plywood, especially if the plywood has been compromised by the elements.
So in addition to having the sidewall sit on top of the frame and polyurethane glued to the bed, it is a good idea to put 3.5 inch bolts through the sidewalls and through the wooden bed's wooden frame (made from 2x2s) with some big flat washers. Position the bolts about a foot apart.
Its really just a matter of having someone help you position the sidewall, drill the holes for the bolts, then take the sidewall down and coat the mating surfaces with polyurethane glue, and reposition and assemble with the bolts. Let dry overnight. You can use the wooden scraps cut off the sidewall profile as temporary bracing to hold the sidewalls up.
The Spars
Spars are simply the 2x2 pine wooden braces that will be placed across the roof line. These are polyurethane glued in place and held with wood screws. Standard 2x2s that you get from the lumber yard are usually pretty ugly and rough, so you might want to take the time to rip the sides of the 2x2s with a table saw so that you have nice looking spars. This is especially true if decide not to have an interior ceiling.
You need to take a few items into consideration when locating the spars:
- Roof seams - The 5.2mm luan only bends well across the narrow dimension (across the 4 ft dimension on a 4x8 sheet). So you are looking at a seam every 4 feet. You should plan on attaching your first sheet to the front of the wooden bed frame (front of the trailer), so from the bottom of the wooden bed up 4 feet is the end of your first roofing sheet. A spar has to run under the center of this spot. Continuing up and back, you'll need spars centered under each seam.
- Curves - There needs to be multiple spars to support the front curve. This is a tight curve and even though the edges of the roofing luan will be attached to the sidewall's curved profile, any place where there is not enough support from spars, the luan will tend to flatten out in the middle. So going around the curve you want spars about every 6 to 8 inches. Spars don't need to be so close on the flatter parts of the roof.
- Roof Vent - You need a couple of spars to support the edges of the roof vent and you might as well frame it in at this point.
- Hatch Hinge - Finally, at the rear you want to put 2 spars adjacent to each other to support the hatch hinge.
So the process is to carefully measure and mark where your spars should be and then counter sink holes through the sidewalls and polyurethane and screw the spars in place. You can then fill the counter sinks with wood filler.
