Bare Plywood Subfloor - Treat?

[Bmotion]

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

 

[highdesertranger]

the bottom should be fine. I would be more worried about the top. bare plywood stains real easy. I would seal it with something. highdesertranger

 

[Bmotion]

the bottom should be fine.  I would be more worried about the top.  bare plywood stains real easy.  I would seal it with something.  highdesertranger

Thanks! I left out the fact that I'm going to put down vinyl flooring on top of the plywood.

 

[frater secessus]

Sounds really practical. Tough, easy to clean.

 

[Weight]

It would not hurt to coat all sides and edges of the fitted plywood. Wetness on the metal under the floor could effect the wood. Soo, the furniture holds the plywood down,. What holds the furniture in the never-to-happen collision?

 

[GypsySpirit]

I put my plywood floor in mine 5 years ago. It got wet due to a leak and it's gonna be a bear to replace because I have to unbolt all those things holding it down. I wish I had sealed it. The next one will be sealed, both sides.

 

[Bmotion]

It would not hurt to coat all sides and edges of the fitted plywood. Wetness on the metal under the floor could effect the wood. Soo, the furniture holds the plywood down,. What holds the furniture in the never-to-happen collision?

It would be bolted to the walls and the floors in certain areas. Just the floor would not be bolted. But the floor won’t move because if the fit

 

[Weight]

I found it easy to fasten the 3/4 plywood to a few well selected points on vans metal floor, then the furniture was fastened to the plywood with ease of correcting my "change orders" with a few wood screws. The furniture was fastened to the walls as well. Just under the windows.

 

[rm.w/aview]

I've always treated all bare wood on any project for either protection or appearance. In your case the treatment would provide a good surface for your vinyl to adhere to, (unless it's floating, then it's for protection). Bare wood of any kind is absorbent, so I'd definitely treat all sides before installation. I just like to be prepared for what could, or very likely will, happen in the future.

 

[Bmotion]

Thanks! Any suggestions on what to treat the ply with? I looked at eurothane but it's pricy per gallon. I don't need a beautiful finish, just smooth on top.

 

[rm.w/aview]

Your choices are many, given that it's an interior wood project. I've used KILZ primer/sealer often in preparation for a finish coat of paint (over kill in your case, though on it's own very complete for you), and though the cost may seem high, it goes a long way. Essentially, most paint will effectively seal the wood for an interior project, so you can price accordingly. Protecting/sealing the wood from absorbing and subsequent staining/warping/weakening is all you're after. A high gloss could provide a nice finish for adhesive tiles to stick to.

 

[Almost There]

I've never treated the undersides or edges plywood floors in any of my vans dating back 42 years now. None have ever had a problem with moisture or wood rot.

As long as the floor of the van was clean, dry and free of holes before the plywood went in, IMO you'll be fine. I do not screw the plywood to the van floor. I depend on the weight of all the cabinetry that is screwed to both the floor and the strapping I installed on the side walls to hold everything together. I also did the floor plywood layout so that all the seams were underneath the various components once they were installed.

I do edge the plywood along the cargo door side for both looks and to keep the edge of the flooring from chipping etc. I also edged the floor in this van along the front edge behind the driving compartment.

 

[Scout]

I dont want to put holes in my floor either by screwing the floor down. But im wondering if the seams will lift up or warp over time. Do you think it would be beneficial to use tongue and groove plywood if all the seams are not under something to hold it down?

 

[dj55]

Have you considered using marine grade plywood? Way,way,way more expensive than cdx but then you save the cost of the sealant and the hassle of painting.

 

[Almost There]

I dont want to put holes in my floor either by screwing the floor down. But im wondering if the seams will lift up or warp over time. Do you think it would be beneficial to use tongue and groove plywood if all the seams are not under something to hold it down?

The seams won't lift or warp  if there is furniture/cabinetry above them.

That's why the layout is the way it is in my van. The full sheet went down where the open space would be. The seams are all hidden under the kitchen cabinetry and the bed frame.

Nothing's going to lift, warp or move.

If you simply cannot do the layout so that the seams are hidden then maybe tongue and groove would be the way to go but try working with the layout first.

I did have one corner (the front passsenger corner) of the full sheet try to lift on me when I first put it in. Within weeks, long before I ever had the interior finished it had settled right down. I had planned on squeezing some adhesive in there and then putting heavy weights on it until the glue dried...didn't need to in the end.

 

[Almost There]

Have you considered using marine grade plywood? Way,way,way more expensive than cdx but then you save the cost of the sealant and the hassle of painting.

No need for any of that as long as you have no holes in the van floor to start with.

That's why prepping the floor of the van, getting rid of rust and existing holes is so important.

I've been laying floors in vans since 1975 and have never used anything except straight plywood. No rotten floors to date!

 

[Canine]

If you decide to paint or somehow seal the plywood, anything you use will make a huge difference in protection since it is an interior application. If it were exposed to the elements, then I would spend the extra cash and get the good stuff. The plywood you are attaching the flooring to could be painted on one side and the edges then leave the top unpainted. That would give a good surface for the adhesive to stick to. The adhesive with the flooring mated to it should provide its own protection. As long as you keep leaks from accumulating, untreated plywood will last the life of your vehicle on an interior application. Like has already been said, painting it won't hurt a bit. Slapping a few coats of paint on a few sheets of plywood isn't a big investment in time or money. Since the plywood will be covered up, you could get a mis-mix for much less money. Who cares what pukey shade of green/brown it is as long as it protects the wood?

 

[yemx]

Couldn't you just use an Exterior Grade plywood?  Not nearly as expensive as Marine grade, and only a few dollars more than standard plywood (Don't use OSB).  If you're still wary about coating the plywood, someone suggested Killz It...  They have anti-mold primers and paints.  I would check them out.  I would also see how well Killz It handles being glued to, since you mentioned you're laying down vinyl sheet.

I too am not a fan of the idea of screwing the plywood to the van's floor.  But for peace of mind, I'm going to glue some area's down with Liquid Nails "Fuze It".  Overkill?  Perhaps.  But I feel that good construction adhesive is a good compromise between a floating floor and one that is secured to the van floor via screws.

 

[RoadtripsAndCampfires]

I will be using Kilz on all sides of the boards on my cargo van except the underside of the floor because that is already coated by the manufacturer. If you've ever seen woodrot or dealt with it you would know why. Things happen. Leaks happen. Spills happen. Life happens.

 

[RoadtripsAndCampfires]

CORRECTION! Not Kilz. We use ...

Zinsser 1-2-3 Water-Base Interior & Exterior Primer for all surfaces. It's Mold and Mildew Resistant Film and Rust Inhibitive.

I am (5/23) painting the inside wall boards that will face the insulation. I was surprised I had to buy a second can of this stuff but the plywood walls are SOAKING IT UP. Just imagine if that were water, such as a leak or even frequent condensation from using a propane heater/stove.

If my boards soak in water for a long time they will be destroyed but they are protected from minor problems giving me some time to fix things. At least this is my thinking. I am doing the edges as well and will do a coating on the side that will face to the interior. Surfaces inside will be a variety of wall coverings over that (paint, tin, waterproof, etc.) I am not going for the cover of Good Housekeeping but rather.

I am sure big buck RVs aren't getting the wood protection my little cargo build is getting. I bet mine lasts longer.