Roof Rafters…
The next step was to figure out the roof and ceiling. The truck came with a single piece aluminum roof and two crank up roof vents with cheesy little 12V fans. The roof supports are steel top hat rails on 24” centers. I climbed up there and it was clear that it was never designed to take the weight of my fat carcass. It was flexing underneath me and if I had been anything but ginger about it I am sure I would have permanently flattened the steel supports. As a matter of fact, I suspect that they were already somewhat flattened by people walking up there when they installed the factory original roof vents.
The clearance from the floor to the underside of the aluminum roof is about 6’7” in the center, minus the top hat rails and the ¾” of arch that reduces the clearance near the sides. I am only about 5’8”, so that’s 11” of clearance, but I plan to add about 7 ½” of insulation and structure between the floor and the ceiling, so that brings me to just 3 ½” of clearance, not counting fixtures or anything that might hang down. I know from personal experience that anything over my head that doesn’t actually hit me doesn’t bother me a whit. Clearly, others who are taller, or tend to feel a bit claustrophobic would need to start with a truck that has a taller box. Fortunately I have only one person to satisfy and I could care less about resale value, so I can do whatever I want.
I decided the easiest way to make roof rafters was to carve them out of 2x6’s (actually 1.5”x5.5”). I used the table saw to cut the ¾” crown in the top edge and the circular saw to do a lot of creative notching and carving on both ends. The idea was to fit into the aluminum extrusions that join the FRP side walls to the aluminum roof. They fit in between the side rails on a diagonal and then straighten out for a tight fit. They also have notches for 2x4’s (actually 1.5”x3.5”) that run the length of the box, flat side down. Together with 2x2’s (actually 1.5”x1.5”) they form the inside corner that will support the plywood inner walls and ceiling.
In general, my plan was to put the rafters on 24” centers alternating with the steel top hat supports, but in places I needed extra strength. I plan to put a roof top air conditioner over the 14.5” square opening that was originally the rear crank up roof vent. Those things weigh about 100 pounds so it needed to be well supported. I put 2 each of the wooden rafters, side by side, on each side of the 14.5” opening. Fortunately the original roof vent was placed between the existing metal top hat roof supports so I didn’t have to cut or move them.
The ceiling vent for the air conditioner stands proud of the ceiling surface by about 3” so I couldn’t just mount it on the ceiling as is most commonly done. I would be banging my head into it. I could have just made the rafters thinner, like out of 2x4’s, but that would have cost me a lot of valuable insulation. Instead I notched the rafters up 2” to make room for the ceiling vent. This inset box, as it would eventually appear, had to be quite a bit larger than the ceiling vent to allow for room for air to come out the sides and follow along the ceiling surface before dropping down. I ended up padding out the opening with 2 more 2x4’s on both sides making the inset box 23.5” by 23.5” by about 2.5” deep after the ceiling plywood panel is installed.
The forward vent was boxed out in a similar manner, but with only one wood rafter on either side of the 14.5” opening. My problem here was that the original location of the forward vent would have put it about half way into the top bunk sleeping area. Since the forward vent would serve to some degree as a skylight, and also as a fan powered air vent, I didn’t want the unwanted light or fan noise in the sleeping quarters. I did, however want both in the living quarters, so I needed to move the vent back 1 bay, or 24”.
The technique is simple enough. Unscrew the vents (both of them), pry them up off the roof and then clean off the remaining caulking. One of the vents was then cleaned and straightened in preparation for putting it back on in the new forward location. I could have bought a new one I suppose, but why spend money on what you already have.
To be continued…
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