"Existential Angst" wrote in message
...

Awl --

I'm looking to make a 4 ft x 6 ft base for some apparatus, out of 1/2"
plywood, for outdoor use.
It works well indoors, but I'm wondering if I can make it *truly* waterproof
for outdoor use, with enough coats of poly, epoxy, or some clear plastic
coating-type finishes I've seen.

Not that familiar with wood/coatings, beyond having done my floors with a
water-based poly+catalyst, with mixed results.

Also, I know there's HD 1/2 plywood, which you can break across your knee,
and there is real 1/2 ply, from a lumber yard. Are there even
harder/stiffer grades? I'm not necessarily looking for furniture-grade
plywood, but maybe that is indeed the stiffest. Cost, bang for the buck is
a factor.
Maybe other "engineered products"?

Appreciate all input.
--
EA

No plywood available at box stores including treated plywood is rated for
ground contact.
If you coated both sides and edges with fiberglass and epoxy with an
overcoating of epoxy (or polyester resins for both coats) you would have a
chance of lasting over two years.
Why use wood? Why not go with a few cross pieces and decking made up of the
plastic deck boards? It will last without change.

-- Jim in NC