There are several ways to go. You can go with Marine grade at about $90 a sheet, MDO plywood which runs about $40 a sheet, aluminum which I would guess would be on the pricey side, but not sure, or you could go with exterior grade plywood and just fiberglass the top, bottom and sides. All of these options will last 10 to 15+ years, except the aluminum which will outlast us all, just avoid the pressure treated. I have been recently informed that the chemicals in it are toxic, and you can not fiberglass it, because it will de-laminate over time. I plan on re-decking mine in the next few years and will most likely go with exterior grade ply and fiberglass it, and then run gelcoat across the top. This way I will also go with snap in carpet that can be removed for the winter season, and so my wife can change colors at her whim and if my wallet allows. This way I plan on doing it once, and barring any damage, it could be the last time it will ever need to be done.[/QUOTE
Looked at the MDO ply. That looks like it might be better than marine ply? Im trying to find a place to order some, anyone ever use MDO?