(Revised 13-Sep-2005 to add notch cutout in walls)
Cut two temporary spars. These are 1x2 pieces of pine, 58 ½” long. Cut this using a miter saw. You want your spars to be as square and perpendicular as possible.
Position the walls so that the bottom of the wall is flush with the bottom edge of the trailer. A partner would be helpful for this step. The back edge of the wall should be flush with the back edge of the trailer. It might helpful to use a piece of scrap wood as a straight edge against the bottom edge of the frame and wall. Once you’ve got the wall positioned, install a 1 5/8” drywall screw in each end. Repeat for the other wall. Then, quickly install your temporary spars putting in a 1 5/8” drywall screw in each end. One spar should be in the middle on the teardrop, near the ceiling vent. The other should be positioned where the hatch starts. Grab a framing square and check to see if your walls are perpendicular to the floor.
The sidewalls now need a notch for the hatch. This is a 3/8” offset cut all the way from the poplar spar to the floor. Use a marking tool or a t-square set at 3/8”. Strike a line offset from the outside profile of the teardrop 3/8”, from the spar to the floor. Also mark the floor and spar locations on the sidewall in the offset area.
Disassemble everything.
With your walls back on the saw horses, cut out the 3/8” notch with a jig saw. Save the cutouts, you will be using it as a template to make your hatch. Sand the notch smooth with a belt sander.
Tip: If you forget to cut the notch at this point, you can cut it after the walls are installed. But it is so much easier while laying on the bench!
Put roofing tar on the bottom edge, and on the inside edge of the wall that will be facing the frame. You’ll only do about the first 2”. Do not coat the part of the wall that will be receiving the glue.
