Corrugated floor insulation foam board

If you are in Chicago you are only a shoty ride to Elkhart where they have all of that kind of stuff in the supply stores.

Hope your taking pictures. Would love to see it.

Thanks everyone for your input.

I checked with every RV builder, supplier and dealer around or online and nobody has that profiled floor anymore. So I ended up filling the "valleys" with 2" wide strips of 1/8" foam rubber tape (takes two layers to fill the 1/4" valley) then lay a flat 1/2" semi-rigid foam rubber pad on top. I got a flat, walkable, pretty well insulated surface, no plywood (first I don't want the weight, second I already have finished wall panels and I would have to cut them off if I add anything thicker than the old carpet my van had). The finished floor will be the dime patterned rubber they use for garage floors.

How about one outta the box idea. Spray foam like Great Stuff then trim it back level with a saw. I've seen this done on the studs of a garage.

I had a conversion van several years ago and the floor had the same thing on it and it came from a RV van conversion place, just google van conversion shop in your area or the closes one to you.

Foam boards are commonly sold at artist supply stores for using as poster boards. You still need to put down plywood screwed or bolted through to the metal floor ribs. The suggestion to use Dynamat or Hushmat is a good one, It is a black rubberized sheet of about 1/8" thick faced with aluminum foil. It adheres to the metal surface and you follow the ribs rather than bridge them. It makes for great sound deadening as well which what it is primarily for.

just use dynomat then put your wood ontop of that

gbopp, this was done by the conversion guys, it's not part of the standard Chevy passenger van (not a Chevy part). And it's a 2000 model with no visible brand marks so I have no idea who built it or whether they're still in business.

Check with a chevy dealer or, an auto body repair shop?