Questions re floor insulation

[songsparrow]

I've been reading some build instructions and looking at photos of builds and I have two questions about floor insulation. If I'm understanding correctly, after you've applied the tar to the bottom of the floor (the underside that will face the road), you should stick your insulation panels into the wet tar.

Questions:
1. Do you use anything else to hold the insulation panels in place, or is the tar an adequate glue?
2. Do you paint tar over the insulation or cover the insulation with any type of protective skin? If not, doesn't it get damaged by stones and such being kicked up from the road?

[alffink]

SongSparrow

That is basically how my floor is insulated.
1) painted all surfaces of the subfloor with the asphalt
2) Foam was cut to be pressed in place (tight fit).
3) used several deck screws with fender washers as a backup
4) used the asphalt over the foam

only have about 1,000 miles on my tear with about 50 miles on desert, sand/dirt roads, with no obvious damage to the foam at this point.

[Miriam C.]

What he said unless you are making a sandwich floor.

[Nobody]

I waited 'til the roofing asphalt was dry then cut the foam for a 'press' fit & used a small 'bead' of construction adhesive. After everything was in place, I used the air stapler (1 1/4" staples) to fasten scrap strips of wood to the frame as 'keepers' for the foam insulation. Left it 'raw' with no covering or paint on the foam. I've pulled it more than 6000mi since built, many of them over rough dirt/rock roads & the foam has sustained NO damage & still looks almost pristine except for being dusty. This is what underside of the floor looked like before installation on the trailer frame.



Here's a somewhat limited view taken less than a month ago when I was installing my A/C ductwork. As you can see, the insulation still looks good.