? on glues for roof foam/ foil covered insulation

[ScouterMom]

Took the 73 starmaster out on it's maiden voyage last weekend.....  

towed like a dream, floor & beds were solid, mattresses not bad, no leaks, canvas is almost TOO tight (is it possible I shrunk it by scrubbing it? seriously, its as taut as a drum!) we were plenty warm with the Mr. Buddy heater, loads of room.

We made our deadline, got everything fixed in time for the trip, except to check out the propane system (furnace & stove).  didn't really expect to get that far anyway, so we didn't use any of that - used the lttle grill and backpacking stove for cooking and the Mr Buddy for heat.

One thing though - I had replaced a section of the moldy roof foam with new, foil backed insulation board.  I had heard that some glues dissolve the foam, so I made sure to get foamboard with the foil coating so the glue wouldn't eat the foam. I glued it with foamboard adhesive (construction-type in a tube for a caulk gun) and it had seemed to hold well during the past weeks of repairs and up and down in the garage and yard.  But when we got to our campsite after a two-hour drive, set up the camper on Fri and gone to bed, heard a weird noise, and one corner of the foam board had popped loose.  (you should have seen our dog, Fizzy's, face - she couldn't figure out where that wierd, slow, glue-popping sound came from! LOL!)

neither did we at first - but about 1/3 to 1/2 of the board was hanging by the end of the weekend.  

I had put some braces into the roof corners - mostly as something to hang the clamp lamp to - and the brace ended up holding up the corner of the foam so it's weight didn't pull the whole thing down.  (there's photos in my album of the trip - http://community.webshots.com/user/TLauraT7)

Problem is, why did it pull loose in the first place? I used a glue specifically made for foamboard.  perhaps the shifting of the camper during the drive broke the glue seal to the aluminum?? if so, what should I use that will 'shift' and flex without breaking loose?  We may eventually want to re-do the whole roof, so I need to address this problem first, before I start tearing off the rest.

I thought we used enough glue - we had lines all over the whole piece, about 4 - 5" apart all over. Maybe it just thinned out too much to hold well? how thick should it bee? there were no guidelines on the glue package. I have thought about using some kind of 'expanding' glue, or foam - like gorilla glue, or that 'great stuff' foam insulation filler to glue it on - but am afraid that would expand TOO much - plus, how do I clamp the whole thing together while it dries?

any ideas or suggestions would be appreciated.

thanks -

laura