by Artificer » Sat Jul 09, 2011 10:52 am
Wind: Metal buildings are made to survive 80mph winds. You will have many more fasteners, probably, so it should be secure... just like bobhenry said. Typical post frame building construction has purlins (2x's between the trusses) no more than 24" on center. This is what the metal is screwed down to. I can see your roof having trusses/ribs 24" on center or so, and 2x2's every 6-12". If you still use the typical 9" spacing for screws, you'll still have 2-4 times as many screws holding the metal on. I would make sure that you didn't have more than an inch or two of unsupported metal, and none on the leading edge/front of the trailer.
Bending the metal: depending on the thickness, you shouldn't have a problem putting in the small bend. I agree that the roof will drain better with the corrugations running along the bend.
Metal: the sheets are either galvanized steel, or galvanized and painted. Corrugated metal typically only has a glavanized coating. If you try to aneal the metal, the coatings will be burnt off. The metal is mild steel, so it doesn't harden. Annealing will not do much anyway. There are other corrugated materials (fiberglass, polycarb, Onduro), but I think steel is the best thing to use.
Soffit on the front: If you really want a significant overhang on the front of the trailer, you will have to design in some strength. Extend the 2x2's (if you use that method) all the way to the end of where you want the sheetmetal. cover with a couple layers of 1/4" plywood thats glued together. You get your curved surface, and the plywood will add a lot of support to the metal. I wouldn't go more than 24" out on the front without more support or larger purlins.
Sealing the edge: I wouldn't use the foam material to fill up the corrugations. I've seen too many of those pieces on the ground after big wind storms. May not happen to the vardo, since they'll be on the sides, but why chance it. The wooden pieces with silicone caulk will make a very tight seal, and provide a sturdy backing on the end of the sheets where you need it.
Michael