Adhesive for Aluminum roof to plywood?

theoldwizard1 wrote:
ItsyRV used an urethane adhesive which DOES have more flexibility than most adhesives. I assume by "bead and roll", he meant that a bead of the adhesive was applied to the wood (like where the rafters would be) instead of the entire surface (like a contact cement), the aluminum is then laid down and rolled.

I am no expert, but I think I would add the screws over the line of the adhesive. "Belts and braces !"

The uncovered roof surface was metal framing along the sides, leading and trailing edges. Two additional metal ribs were placed at the air conditioner. Some of the bridging was also metal. The remainder of the ribs, bridging and attachment supports were wood. Between all this was the standard rock solid foam with a thin wood top surface.

The two part urethane adhesive was applied to the metal framing in a thick bead. The reminder of the surfaces had another type of thing lightly sprayed over it. I have no idea what that was. The aluminum was attached at leading edge with screws through the transition. As it was being laid down, a heavy floor roller was used to ensure contact and to make sure it was tight with no ripples, bulges or indentations. The edges of the roof (front, back, sides, and around the a/c opening, were screwed down through the transition and edge pieces. I did not get to see everything they used or did but was able to see enough.

Years later you can walk on the roof with no flexing at all. It's as if its one solid roof. There is no separation between the aluminum and the surface underneath. I belive they actually used three different adhesives; wood to wood, wood to metal, metal to metal. As a way of clarification, this was not done at an RV place but by those who service those emergency command type vehicles and trailers.