Luan or Bendy Board

[Chilton82]

So as of yesterday the only thing that I could find was 3/16 luan. I tried getting it to bend to my interior 22 inch radius. To help shape it, overnight I strapped down with webbing on the exterior, hit it repidly with a spray bottle, tightening very slowly. In my 90 degree F garage, with the help of the webbing and over about six hours I got it to take the curve. However, when I came out this morning the front of the board had delaminated.

This morning I did some really random phone calling and did end up finding 1/8 luan as well as 1/8 and 1/4 bendy board. Obviously I should've looked harder first but I thought the 3/16 was going to make it. The luan is literally half as expensive as the bendy board, coming in at about $15, $31, and $33 respectively.

So my question is what should I go with? I'm skinning the exterior with aluminum so, can I get away with 1/8 inch of either material? Will the luan easily take the bend and is one layer enough? If not is one layer of 1/8 bendy board enough? If not will 1/4 inch bendy take the curve?

Obviously like everyone else, I'm trying to make this build as frugal as possible. And seeing how I just ruined a $25 board last night I'd like to not make the same mistakes.

[Jdw2717]

I found 1/8" 5' x 5' birch plywood at a wood supplier for cabinet shops and used one layer on the outside on the roof and one layer on the inside ceiling. No aluminum skin just paint. You don't want to push on it too hard where there is no stringer underneath but structurally it is very strong. I think it was about $20 a sheet but was worth it for the ease of use because you can turn it so the grain bends easier.

[Graniterich]

I use 1/8 Luan with. 040 aluminum, way strong enough for me! Not sure what the advantage to 1/4 or double 1/8 would be with the aluminum skin

[skinnedknuckles]

I also used 1/8" 5'x5' birch plywood from a local woodworking supply company and covered with .040" aluminum. It was very flexible and formed around my campers profile great.
Paul

[halfdome, Danny]

Not sure what the advantage to 1/4 or double 1/8 would be with the aluminum skin

Double 1/8" Baltic/Russian Birch glued together creates a very strong pre stressed roof under glued on .040 aluminum.
I can actually stand/kneel on the roof of the teardrops I've built.
Bender board is for interior radius work like store fixtures, reception desks and the like.
I've used it a lot for that interior application and wouldn't use it for anything else.
I've had sheets of 3/8" bender board that have broken under the stress.
Danny

[MarkusMasonis]

1/8" Baltic Birch. My regular birch would not be up to the task, but the BB was downright bendy in the right direction. Very strong. I just flopped it over the 14" radius, and felt like it could have done a lot tighter. No hint of delam or damage so far, and no need to wet or steam.

You'll be able to tell what will bend and what won't in the store. Play with a few different types.

I plan on fibreglass epoxy coating, priming, and painting with topside boat paint.

[MarkusMasonis]

Oh, should mention that the roof is several layers -- 1/8" BB, then 1-1/2" structural foam, then 1/8" BB, all laminated. I can literally do chin-ups on the cut-out for the skylight. With fibreglass, I think it should be strong enough. However, don't underestimate the cost or weight of the glue you'll need to laminate this much material!

[Chilton82]

I ended up getting the 1/8 BB as there weren't replies to the thread when I got to the lumber yard. It's about an hour away from me so swapping it out would be a bit of a pain. I messed around with the 1/4 BB in the yard but trying to make the 90 degree turn lead to A LOT of popping and creaking. I wasn't feeling too comfortable with it.

Anyway the headliner is done (talk about a female dog to get in) but the bender board doesn't feel like it would hold up too well. So, I ended up reinforcing the roof with quite a few extra cross beams and it feels pretty study above our heads where we would probably spend a lot of time leaning.

So now I have 1/8 BB left to skin the exterior after I insulate the roof. I also decided to drop down to 1" insulation on the roof because I think squeezing the 1-1/2" would end up pressing onto the BB and give me bulge spots especially on the curves. I ended up getting the better 1" insulation with an R6 rating to make up for it. I couldn't find 1-1/4" locally, maybe I'll look for 1/4 to place on top to take up more space. I've got some 1-1/2 remnants laying around so I'll play around with both and see what happens. Maybe just the 1" around the curves.

It's a learning experience.