Glue or float aluminum roofing and sideing

[fm-usa]

Thanks for all the comments. I've got a call into Dibond Technical Support and will ask them the question. Hopefully I'll get a good answer that I can share.

By the way I did a search on this forum for "Aluminum Composite Material" and found a good thread. Although it doesn't definitively answer my questions.

Thanks again,

I believe I may have found an answer from a similar product user.
Center the panel and use one large dot of good quality silicone glue in the very center of the panel. Expansion will be divided in half. A large glue dot keeps the panel from racking.
If the panel is long, use 2 dots about 1 foot apart and centered.
Adjust glue placement for doors and windows.

HOPE THIS HELPS

[RunnerDuck]

Thanks for the suggestion Floyd but after talking with my neighbor, who's built two TD's with Dibond, I think I'll use his method of contact cement for the whole thing. I guess if it worked for him it should work for me.

Thanks again,

[fm-usa]

Thanks for the suggestion Floyd but after talking with my neighbor, who's built two TD's with Dibond, I think I'll use his method of contact cement for the whole thing. I guess if it worked for him it should work for me.

Thanks again,

I re-read this post, missed the 3/4" material which is a rather solid base to go over.
The info given was 5mm interior and exterior sealed all sides. 1/4" ply as a frame. With 3 outer layers PMF, the whole thickness worked out to 3/4". All layers were glued together for 9 layers (plus PMF and sealers) sturdiness.
For me that's rather heavy but he's pulling behind a car.
Good to know you've got it fig'd out.
.

[wingloader]

Has anyone ever used the 3M super 77 spray adhesive? That is some sticky stuff.

If I do use that (or some other kind of contact cement), will that cause issues? I'm just thinking that when the aluminum expands and contracts with sun exposure, where does that stress go? will it cause buckling?

I did read a comment about using a layer of foam between the aluminum and the "wood" in order to have some "give". I don't want to do that because it will be a LOT easier to dent the aluminum because of the foam.

Thanks!
Joe

[bobwhite215]

Thanks for the suggestion Floyd but after talking with my neighbor, who's built two TD's with Dibond, I think I'll use his method of contact cement for the whole thing. I guess if it worked for him it should work for me.

Thanks again,

How did the dibond construction work out? I am getting ready to start my build and plan on using it for the outer skin, adhering it directly to a 3/4" plywood skeleton.

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[RunnerDuck]

How did the dibond construction work out? I am getting ready to start my build and plan on using it for the outer skin, adhering it directly to a 3/4" plywood skeleton.

It went well. I certainly learned a few things. First and foremost is "Don't pre-trim the Dibond to perfectly fit the shape of the trailer." It would be much easier to attach it and then trim with a flush cut router after it's bonded to the wall.

Another thing I already knew but...

"Don't let the Dibond, after the contact cement has been applied, touch any part of the wall before you're ready to commit!" We screwed up and got a "premature touch" and it was a bitch getting it off without damaging the Dibond. We got lucky and got it loose but oh boy what an effort.

In hindsight I'd do it again but just not trim it first.

I hope this helps and good luck,

[fm-usa]

It went well.

Let the fun begin!
KennyB

[Camp4Life]

Has anyone just used a foam/rubber strip (like weather stripping) that has adhesive on only one side? So you either stick to the alum, or the trim, and then fasten down the trim all the way around the alum? This would be a literal floating sheet since it wouldn't be fastened at all, just held in place by the trim. I imagine as long as all 4 sides are held down and it has nowhere to slide to, it should stay in place no?

[fm-usa]

Somehow that reminds me of the 1920's FLAPPERS.

[RunnerDuck]

What I did on my galley hatch and plan on doing on the roof is Loctite PL all the way around and then staple to the sides.

Skinned Hatch.jpg (233.46 KiB) Viewed 3843 times

I know it's not a full "float" but it looks like it will work.

Before I do the roof do you see any real problems with this approach?

Thanks,

[fm-usa]

As you know part of the overall stiffness and strengths of laminates is the solidity of the layers.

[Andrew Herrick]

This is such a great topic. Lots of good info from other builders. I am going to put 1/16(.063) aluminum diamond plate on the front (modified Grumman II profile) as a stone guard over my two layers of 1/8 Baltic birch. A local sheet metal shop can roll form it to my template. That will save me the hassle of bending it myself.

I plan to put two coats of CPES on the BB, then attach the Al with screws through enlarged holes. I'll use SS washers under the screw heads and only snug them, which should allow the Al to expand/contract. I'll put silicone caulk under the edges of the plate. It should be flexible enough to allow for expansion. I will leave a few gaps in the caulk at the bottom to help drain away any water that does get in.

Comments?

I checked your profile credentials, Dr. Grumpus, and I see you're a retired aerospace engineer. I'm only a lowly college graduate in mechanical engineering, so I may be way off with this ... but ....

If you plan to float your aluminum skin, and you firmly fasten the perimeter of the aluminum, doesn't that allow the remainder of the sheet to expand/contract freely in the orthogonal direction? Basically, it can "oil can" when hot, and shrink back to flat when cold. Now, your idea was to only snug the fasteners and allow the aluminum to expand/contract in a planar direction, which would seem to convert all the force of thermal expansion into bearing stresses at the screw/aluminum interface. Since aluminum is so much softer, would this just deform the sheet metal and lead to possible water leaks?

Wait a minute ... you plan to attach the aluminum with enlarged holes. Ah ha! (I'll still post this comment in case anyone else had the same concern). So that takes care of the bearing stresses, and you're assuming that the washer is large enough to cover up the hole and prevent water intrusion. Good idea! Any reason why you're going with a stainless steel washer over a rubberized one, like on a roofing screw?