yet another insulation question........

hey guys,
im about to get ready to start on the step van projects interior walls.....

i have read everything i can find here, and other places about does and donts with insulation and steel bodies.......but cant find anything definitive on aluminum bodied applications.....

i have watched several youtube videos of guys using the hard foam sheets on flat wall areas and just gluing them on with some sort of liquid nails type stuff

right now my idea is to use reflectix on the outer skin, then glue the board foam to back of that to build out to the level of the wall studs, then a combination of screw and glue for 1/8" luan board to the studs and foam board, and then finally to cover that with white FRP from home depot, or lows, depending on price.....

for the floor, im planing on 1/4" plywood just to smooth out the lumps and bumps, maybe using spray foam to fill in any large dips that may be in floor (its aluminum also).....

if i go through and fill in all of the nooks and crannys with spray foam so as to basically make a solid composite wall, am i right in thinking i wont have to worry about condensation and the such?

the van is a 78 p20 all aluminum step van

1/4" plywood sounds a little thin to me. I always use 3/4" on the floor. Aluminum doesn't rust so that won't be a concern. I live in a very hot( up to 118 degrees) dry climate so I have never had to worry much about condensation or rust. I was stationed at Fort Bragg in N. Carolina so I know about the humidity there.

well, the idea behind the 1/4 inch is it will be resting directly on the aluminum floor, so im expecting the aluminum to be the structural aspect, the 1/4 ply is just to give me a smooth clean base to add a flooring product to.....

the p20 is only a 3/4 ton van, so i am trying to come up with reasonable ideas to keep the weight at a minimum..... right now i am estimating about 1500 pounds in equipment and materials will be going in, and thats not counting stock and supplies, so im really going to be pushing the limits

and yes, no one will ever die of dehydration in these parts......the humidity levels around here in july and august are insane, you can actually feel the air

of course, if i laid down a thin sheet of hard foam under the 1/4 ply, that would help "fill in" dimples and low spots, and soften, and insulate the floor i would think.....

if thats a viable option, maybe my 43 y/o dawgs wont be barking so hard at the end of the day!

I would use a fiberglass resin from Napa to fill in the dips since it will not hold moisture. I live in N.C. so I know all about mold and dew points. What I am doing is the fat mat on the outer shell for noise and some heat transfer.Then I am installing the reflective bubble insulation "loose" in the walls. The key is air gap of some sort to allow any moisture to dry. That foam board may become a sponge in the late summer down here IMO.

how well does the resin take flexing ?
as far as the foam board becoming a sponge, thats the reason for completely filling in behind the ply, if there is no space for air, then there cant be condensation correct ?

Correct- assuming you have a closed cell foam product,and flexing would be no different than bondo on a door panel.

cool cool.....
well, i will be getting started soon..... we will see how it goes