GPW wrote:Thanks for the Info Pat !!! I'm at that vent stage too ... Are you adding wood around the vent ... ??? I was thinking to skip the wood and just glue/foam the vent in place with some more canvas strips on top to seal it , or maybe just some Eternabond tape ..

Would be quick ... Don't think the vent will blow off the top .... nothing else has .... yet ...

I believe the vents without fans are certainly light enough to be put on the roof of a foamie with appropriate weather sealing and without additional structural supports. If one worries about fly-away vents, you can always put a thin supporting piece of metal inside the foamie glued to ceiling for bolting. I replaced one of these in my old popup with no additional support other than the thin aluminum roof. With appropriate silicone and butyl tape (I think that's the stuff that came with it), it never moved as I warp sped down the highway with it.
Any vents with motors like the "fantastic fan" are significantly heavier and have more weight with the addition of more gadgets in place. I would recommend some additional support for the 1 inch foamie roof, but doubt you'd need any more with the 2 inch roof. Again, the addition of some thin metal if you are worried about bolts compressing the foam, but that's it. Eagle has a perfect setup in that a wooden frame was built in and connected to her spar ribs that hold up the 1 inch foam.
Hugs,
Ratkity