Bulkheads: Solid vs. Sandwiched

[CYi5]

I've pretty much settled on sandwiching my walls for insulation value, but am still on the fence regarding my rear bulkheads.

Each one is relatively small, 1.5x5 ft. and 1.75x 5 feet. Is there even a point to doing these sandwiched? If my calculations are correct regarding weight, each one (if solid 3/4") would come out to only 17.5 and 20 lbs.



Since the walls, hatch, and floor will be sandwiched, is it safe to save some time and potential screw ups by just going with the solid ply? This will be a four seasons teardrop, just making sure i'm not missing anything here.

[Jdw2717]

I made mine hollow which left a path for wiring that I added later. It was not planned but worked out nicely. I would build in the flexibility if you have the materials.

[KCStudly]

I built mine up with 3/4 insulation inside and routed wire paths thru the foam before putting the second skin on.

I did have a lot of extra cedar framing in there because of the 64 inch width on my cabin and the smaller panels, giving a place for the seams to land on as well as backing for all of the different cabinet and counter ledgers. It was not super light, but I had solid wood to screw into on the edges, so no splitting plies with screws. Also, I only used three pocket screws along the bottom at the joint with the floor (where they can be hidden behind the under counter dividers) so to me that is a plus not having to look at or hide the pockets.

[rowerwet]

mine is only one skin of 1/4" ply framed with 1"x 1" with the voids facing in, I plan on putting foam board in the voids someday, and then making the inner skin of glued on carpeting/hull liner. No need for a solid inner skin that I can see.

[tony.latham]

I've got both.


I used 3/4" Birch ply for the bottom since my cooler and water jug were going to butt on it and I was looking for strength. Perhaps overkill. The top is sandwiched, 3/4" foam and 1/4" subfloor plywood.

I think it's a coin flip. But I pull over some rough roads too...

Tony

[aggie79]

My bulkhead walls are insulated sandwich construction.

Part of the reason was due to my hatch construction. When my sidewalls were erected, I attached them to the completed floor and bulkehad framing. Because I wanted to frame the hatch in place, I did not add the skins to either side of the bulkhead framing. This allowed me to temporarily screw the outer hatch spars or ribs screwed to the sidewalls (through 1/4" spacers.) After the outer plywood skin was glued to the hatch framing, I crawled through the bulkhead framing and remove the temporary screws to free the hatch.

[bobhenry]

The bulkheads are an important element in reinforcing the body. They are also a great place to hide all the electrical wires. You might concider looking at a method similar to a hollow core door a solid wood frame of 1 - 1 1/4 fir with a 1/4 plywood face on both sides. In fact a 1/2 depth carlon outlet box will easily fit in a 1" wall so you could incorporate switches and outlets in the wall. The whole 21 " x 60" panel faced both sides shouldn't weigh more than 16-17 pounds and will be hell for stout if glued up well.

[grantstew8]

I used a solid board. I'd not considered the wiring at the time, but all the wiring now runs behind the drawers and is tacked to the floor or the underside of the worktop.

[Lgboro]

Mine is cedar strip (less than 1/8" strips) glued to cedar ribs filled in with 1 1/2 inches of blue foam insulation with no wood on the storage side. The layers will be plenty strong no matter which way you go. Attachment method will have more to do with potential failure than which way you choose for the wall.