Bare Plywood Subfloor - Treat?

[John61CT]

Glidden Gripper's pretty cheap, very very adhesive and good waterproofing.

 

[BinDerSmokDat]

One of the reasons to seal plywood is not for rotting, even with the worst condensation you won't get plywood to rot in the van.
But with CDX you might get delamination and if you have any leaks, you will get water staining.

I treat my van build like a boat build.
All 6 sides (yes 6, top, bottom, left, right, front and back) of every piece of wood is sealed with either clear polyurethane or Durabak brush-on bedliner. This includes wooden stringers and ply that are treated on all sides BEFORE assembly.

The fewer absorbent surfaces in any build that will hold moisture, the better off you are.
It's the same reason I don't use any batting type insulation (fiberglass, hollowfill, thinsulate).
While those things won't technical absorb water at the individual fiber level like cotton, the dense batting will trap moisture. Especially paperfaced insulation.

Eliminating absorbent surfaces in a build is important.
If things do get wet/dewy you can dry the interior quicker if water isn't absorbed by anything.
At the minimum, paint every wood surface to help seal it. Ideally oil-based.
One plus is if you paint the interiors of cabinets and bins, a light/bright color, it makes things easier to find.

 

[66788]

Hi everyone,

I just cut my subfloor for my van. I want to keep it floating, no insulation, no glue, bolts or screws. I figure the cabinets and other stuff will hold it down.

The van floor allows for natural airways for ventilation but should I worry about condensation under the floor? If so should I treat the underside of the plywood with something to protect it?

Thanks,
Blake

Definitely treat it with something, even if it's just an oil based rub.

Also, I secure all my plywood floors with elevator bolts prior to installing another surface or  accessories on top of it.  In a roll over accident, floating floors are no good.   When securing cabinets and beds to the floor, it's nice to have the floor secured to the vehicle.

Just a thought.

 

[craggers]

Definitely treat it with something, even if it's just an oil based rub.

Also, I secure all my plywood floors with elevator bolts prior to installing another surface or  accessories on top of it.  In a roll over accident, floating floors are no good.   When securing cabinets and beds to the floor, it's nice to have the floor secured to the vehicle.

Just a thought.

I'm building out a older 2002 Savana Cargo Van and when I removed the contractor shelving and Rubber floor covering with a fiber backing ;  the whole thing was Soaked with water and must have weighed 400 pounds !   There are No Leaks in the van roof or walls There was 2 small holes in the floor and alot of surface Rust.  I sanded the floor , repaired the holes with Epoxy, Primed the Galvanized floor with Bull's Eye 1 2 3 primer, Cold Galvanizeing spray, and painted it with Rustoleum.   I also installed a access panel above the Fuel Pump.   I've got some Great Ideas here on this Post Thanks.

 

[Jacksonricher]

You will want to treat all adges and both side, if you do just one side you run a chance of warping. Check with a good paint store or lumber yard. Maybe try Thompson Water Seal or the like.