plywood floor

[rayshound]

Is there any disavantage to using 3/4" pressure treated plywood on the floor besides the higher cost? Any trouble painting it to be seen in the cargo bay?  Thanks Ray

[Nick Badame Refrig/ACC]

Hi Ray,

You may want to reconcider using Preasure Treated lumber within closed quarters,

The chemicals are pretty strong that are used to treat it. I belive some are toxic too.

Nick-

[FloridaCliff]

Hi Ray,

What Nick said and the new chemicals used in pressure treating are very corrosive, or so I am told.

Note the new specially coated screws they have you use.

I replaced several pieces of my floor and the worst were over the rear wheel wells.

I just painted them with two heavy coats(bottom and sides) after I cut to fit and they look nice.

I also used a layer of tar paper(over metal pieces in well) as a backup for any wicking that might occur.

YMMV

Cliff

[prevost82]

I used 3/4 PT plywood over wheel area and used Standard 3/4 plywood on the rest of it.... with no issues. When I ripped the old floor out it was real rotten over the wheel area, it was all painted both sides from the factory.
Ron

[Hartley]

Unless they have changed the formula, Pressure treated may contain high levels of arsenic or other poisons. It is usually
also water-logged in most versions. Gloves and Respirator are recommended on the labels....

If you need to protect plywood, Use something like coppertox which uses copper sulfate and paint with an epoxy paint.
the only other reason would be to keep carpenter ants from taking up residence...

I doubt that a bad termite problem would exist in a bus that would warrant pressure treated.

Use Marine grade if you are worried about lasting a long time. Pay more to get more....

[rayshound]

Thanks Guys, good info. Don't need toxic fumes! I was just looking to put down my floor & the bus is under tarps which leak & I didn't want puddles on my new floor to delaminate. maybe I can paint the topside and later when the bus is sealed I could sand with a belt sander so the oak boards will stick?? Thanks Ray

[Cary and Don]

If water is the concern,  why not use exterior grade plywood, like they sheet roofs with.  It isn't pressure treated and doesn't send off toxic fumes.  Cary

[DrivingMissLazy]

The treatment was changed last year and is, to the best of my knowledge no longer toxic. The treatment is no longer green either.
Richard

[Jeremy]

If water is the concern,  why not use exterior grade plywood, like they sheet roofs with.  It isn't pressure treated and doesn't send off toxic fumes.  Cary

I recently bought a sheet of 3/4" roofing / flooring grade plywood (with all the correct stamps on it), and was really disappointed by how poor quality it was. My first choice for plywood would always be multi-lam Russian birch - a very very good product and good value for money, but not available in 8' x 4' sheets unfortunately. True marine-spec ply (BS1088 - not sure if there's an American equivalent) is hellishly expensive and there is no way I could justify using it in the bus.

For those who have mentioned rotting floors above the wheelwells, one possibility would be to use bitumen-coated ply with the coated face downwards. I've never used it myself, and I suspect the basic wood isn't very special, but I presume that it is very waterproof.

Jeremy

[John Z]

The last step i would do after all my painting etc, would be to spray a good heavy layer of a rubberized undercoating on the bottom of the wood. This stuff stays fexible and should not only help waterproof but could help with sound proofing as well. I have used 3M and it is a great product and have also heard good things about NAPA's version.

[rayshound]

Thanks again for the ideas. On the floor rotting over the wheels I have already done something I hope will help. I had purchased two 5 gallon part (A) & part (B) pour foam and dumped it over all 4 wheel covers. It had fiberglass insulation in the floor that held moisture and rusted the metal skins over the fiberglass wheel wells. I had repaired the metal, painted the entire w/well area with por-15, and poured pour foam in it then cut the foam down to the floor surface and is now waiting for plywood. The foam was for marine floatation in the bilge for boats, I bought from e-bay. I recently bought another 10 gallons from the same person to pour in places before I get a sprayfoam job on the walls and overhead.
                                                                                        Ray

[buddydawg]

AC (grade) Ply is a good option it has one side that is smooth which makes a nice underlayment for flooring etc..  If any of the C side is exposed to the underside elements you could coat that with an epoxy or similar coating.  OSB is another good option as it does not delaminate like ply.

[kyle4501]

RE: OSB is another good option as it does not delaminate like ply. It may not delaminate, but it swells & looses strength when moisture gets in. It is not stable enough to lay hard wood or tile over it (- according to the manufacturers).

As for coating the new wood, the wooden boat restorers use a 'Clear Penetrating Epoxy Sealer' to enhance the life of the wood. I read about this stuff in Don Danenberg's 'How to Restore Your Wooden Runabout'. It has been out since 1972 & has a proven history of almost doubling the life of the paint job when it is used.

If it's good enough for boats that are worth more than a new bus .  .   .    .

The top coat of rubberized undercoating is a GREAT idea!

[Paul]

Hi Ray and All
I Looked into pour foam but the cost was to great in 1/2 gallon kits. Could you tell me the cost in the 5 gallon cans. I also need the Name, address and phone number of the person that you got it from. What bus are you filling with the pour foam and how much will it take.

I have cut the 3/4 plywood the same size as it came from the factory. To do this I had to go to a Riemeier lumber Co. here in the City to find 4 x 10ft AB plywood. The lumber has been painted with three coats, cut to size an set in place. The 4 x 8 ft BC plywood came from the big box store, painted the same way. The 4 x 8 will not lay flat on the floor, the 4 x 10 will. I just have it sitting there till we insulate under it.  You get what you pay for.

Paul
www.incredibus.com

[buddydawg]

OSB can absolutely be used as a subfloor for hardwood and tile.  OSB or Ply exposed to moisture will cause problems.  If you are going to use OSB they make a grade for exterior use.

www.osbguide.com/pdfs/SSflr.pdf