Roof options for folding camper

[Paintsalot]

I’m looking at a few options for how to build a roof of my folding wooden camper. There’s more information in the build forum.
Options: see sketches
1. pmf or vinyl roof over cork and plywood
2. Painted plywood roof with cork adhered from bottom.

I’m leaning towards option one because I don’t want the cork to fall down. It just makes more sense to me to put the cork on top of the plywood. It will be a whole lot easier.
Thoughts?

The entire roof will be lifted by hand when I set up the camper, so it needs to be ultralightweight.
I want to keep the roof under 60 pounds

[S. Heisley]

Why not Styrofoam instead of cork?

[Paintsalot]

Why not Styrofoam instead of cork?

Cork is a better sound insulator. It is also flexible for a curved roof. The other reason for me is that it’s completely renewable.


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[Wolfgang92025]

Paintsalot,

If you are concerned about the cork coming lose, do some testing. With it on the inside it, would be a lot easier to fix/repair.

Desert Moose built his trailer maybe 10 years ago using 1/4 (?) inexpensive plywood and covered it with PMF. The trailer spends most of it's life outside in Nevada and now Utah and still looks great.

[Paintsalot]

I plan to use cork for all the wall insulation. I’m just a little concerned that if I use it on the underside of ceiling/roof, it could delaminate over time from gravity. Good idea to test some samples.
From what I’ve learned so far, the best adhesive for cork is water-based contact cement. Wakol D 3540 is what the cork stores recommend.
I think I would rather have the look of the plywood ceiling, though, which I hadn’t really thought about before. On the walls I’m either going to leave the cork natural or I may cover them with fabric.

For the roofing I’ve been reading in some forums about making canvas canoes. Unlike PMF, they don’t always adhere the canvas to the wood- they let it float, no pun intended.

[OP827]

Painted plywood would not last. PMF is a better option to protect plywood roof from weather. PMF on top of cork needs testing, cork is not as strong base so it might separate and the finished surface may not be as smooth as with plywood.

[Paintsalot]

Painted plywood would not last. PMF is a better option to protect plywood roof from weather. PMF on top of cork needs testing, cork is not as strong base so it might separate and the finished surface may not be as smooth as with plywood.

Agree about painted plywood for roof since 1/8 Baltic is interior grade.
Maybe I can run a test of the pmf over cork over plywood.
Painted Dacron looks possible too. Like airplanes.
Another roof option: gessoed duck canvas with oil paint.

[S. Heisley]

According to this: https://www.amazon.com/Manton-Cork-Roll ... 9bb73&th=1

It reads like it would work really well. You can even get some that has self-adhesive backing. I can't find the weight to compare it to Styrofoam, though. Isn't it a bit heavier?

[Pmullen503]

Painted plywood would not last. PMF is a better option to protect plywood roof from weather. PMF on top of cork needs testing, cork is not as strong base so it might separate and the finished surface may not be as smooth as with plywood.

Agree about painted plywood for roof since 1/8 Baltic is interior grade.
Maybe I can run a test of the pmf over cork over plywood.
Painted Dacron looks possible too. Like airplanes.
Another roof option: gessoed duck canvas with oil paint.

I would use oil paint over wood. Latex is great over foam but oil paint is more waterproof.

I have a bathroom floor covered in cork and sealed with water based poly. Still looks great after 20 years. Do a test piece of cork over plywood, covered with canvas and paint. Depending on how time the cork grain is, I'd be surprised if you can see any difference compared to plywood.

[pchast]

If all you are looking for is weight support to protect the roof bond, why not use a base of 1/8 ply(door skins)

[Paintsalot]

. Depending on how time the cork grain is, I'd be surprised if you can see any difference compared to plywood.

Thanks Pmullen -I bought some 1/4” cork underlayment. Its fairly smooth- so texture probably not noticeable through cotton duck.

[Paintsalot]

If all you are looking for is weight support to protect the roof bond, why not use a base of 1/8 ply(door skins)

Yes, that’s the direction I’m going, I already have some 1/8 Baltic

[Paintsalot]

Hi Sharon, the cork adds about 40 pounds if I insulate the walls and roof of camper with it. It’s 1/4” thick. I used foam in floor.

[S. Heisley]

Hi Sharon, the cork adds about 40 pounds if I insulate the walls and roof of camper with it. It’s 1/4” thick. I used foam in floor.

40 lbs. is a lot, when you're lifting a roof. If you could get it down to less, it would be a good idea.

My roof is 70 lbs., completed, but I'm only lifting one end, so I'm only lifting 35 lbs. That roof is only 4x8'.
I could lift the 70 lb. roof from the floor, using my leg muscles as well as my arms, but not over my head as that would be using only my arms, plus the roof length wobbled when I tried. Recognize also that I used minimal wood for the roof. If I remember correctly, 1/8" Plywood, top and bottom, and 1x1" spars across, and foam in between and the overlapping roof side pieces that keep the rain from entering are 1/8" ply outside with very slight bracing and no inside foam or ply.

I think you said you would be using pullies, so that might help, but I'm not certain.... If you could lift one end and brace it, then lift the other, it might be okay. You could make a small model and see how that works. The sides or end walls might scrape a bit or stop the lifting action altogether. A small cardboard model could help you to discover what needs to be done before the time and effort of building the life-sized one.

I think you plan something bigger so yours would weigh more than mine. Please plan carefully. I want to see you succeed.

[Paintsalot]

Hi Sharon, the cork adds about 40 pounds if I insulate the walls and roof of camper with it. It’s 1/4” thick. I used foam in floor.

40 lbs. is a lot, when you're lifting a roof. If you could get it down to less, it would be a good idea.

My roof is 70 lbs., completed, but I'm only lifting one end, so I'm only lifting 35 lbs. That roof is only 4x8'.
I could lift the 70 lb. roof from the floor, using my leg muscles as well as my arms, but not over my head as that would be using only my arms, plus the roof length wobbled when I tried. Recognize also that I used minimal wood for the roof. If I remember correctly, 1/8" Plywood, top and bottom, and 1x1" spars across, and foam in between and the overlapping roof side pieces that keep the rain from entering are 1/8" ply outside with very slight bracing and no inside foam or ply.

I think you said you would be using pullies, so that might help, but I'm not certain.... If you could lift one end and brace it, then lift the other, it might be okay. You could make a small model and see how that works. The sides or end walls might scrape a bit or stop the lifting action altogether. A small cardboard model could help you to discover what needs to be done before the time and effort of building the life-sized one.

I think you plan something bigger so yours would weigh more than mine. Please plan carefully. I want to see you succeed.

Thanks Sharon for wishing me success on this project! That’s encouraging.
I’ve been Sailing all day, so more of this later.
I’ve been calculating the roof weight.