How do you "float" a roof skin?

[WarPony]

I'm getting to the point of putting on the roof skin and don't want to use a bunch of screws to hold it down because I am wanting to minimize the water holes. The roof vent will have to have screws to hold it in but the rest of it I want to look smooth and pretty.

[madjack]

...when you float the aluminum, you are stictly using the edge trim to hold it in place...in other words, you properly locate the skin and then apply the edge trim to secure it
madjack

[WarPony]

What I am afraid of is the skin "oil canning" when it gets hot out. In my thinking, I should do it in the heat of the Sun so it will be stretched tight when it cools. Will it pull the fasteners out during the winter months? I'm going to use white, epoxy coated aluminum in .032" thickness.

[doug hodder]

Hey Jeff....and old sign trick to keep faces in during expansion and contraction is to drill the hole larger than the screw, like a bunch larger. You then shoot the screws through your top cap and it will allow the material to expand and contract without tearing out....I didn't do that on mine....I just glued it all down...It was nearly 100 here today and I had 1/2 of the roof shaded and the other 1/2 in the sun....Sun side was 145 degrees and no oil canning, or pulling....Just my opinion, but I think that on a piece of material this size, you probably won't get a lot of expansion..I'm a big fan of glueing it down however...It minimizes any movement when driving...for grins, lay the material down on your driveway or on something that will allow it to really absorb the sun, measure it in the morning, maybe run the hose on it and really cool it off and then at the hottest point of the day..see just how much expansion you're going to have to deal with, besides it would be good info. for anyone else...I used .040 mill finish..just my thoughts on it....Doug Hodder

[WarPony]

AH HA!!! I knew Hodder would come through for me! Now, the question comes up again, what to use to hold it down? I would love to slather the top with hi-temp red silicone and lay down the skin. That stuff will never break down.

The other concern I have with floating the skin on is the bowing in the middle. I had a horrible time with the interior roof panel bowing so much that it made the roof spars pooch out and lended a whole new set of problems that I wasn't prepared for.

I got one shot at this and if it doesn't work out I'll use Madjack's theory of "problem/high explosives" then go straight to the teh-killya'!!!!!

[doug hodder]

Jeff I don't know if I am going to be of much help on this...I really do think you ought to do a test like I mentioned...the info would really be valuable to anyone else building and you'll know whether or not it's necessary....If it turns out that it doesn't change much you might want to just glue-r-up...The screws can be easily sealed under the cap trim on the edges...If you choose to glue, I would recommend using outdoor carpet adhesieve, like around pools...It gives you some working time for it and isn't a 1 shot thing like contact cement...I know you'll figure it out....I'm doing a tenderloin on the grill tonight, you got me hooked after Minden....Doug Hodder

[DestinDave]

Nothing to do with the thread but we just finished a salmon slab and shrimp kabobs on the grill. Hard to beat que'ing...