Sealing the tub deck

So I've finished building the platform for a drop-in fiberglass roman tub, and I'm wondering what you guys would do next.

The Executive Design Committee said she wants the top and front to be finished with this dark wood lock-n-fold flooring she found on sale somewhere. So before I start putting that down, would y'all suggest something between the 3/4-inch plywood and the flooring that might help with the fact there will likely be water around?

I can't imagine typical wood floor underlayment has much in the way of water resistance... I'm thinking cement board, but can't help feeling that's overkill. My other thought is to just seal the heck out of the wood after it's snapped together.

Thoughts?

Recipe for disaster. Most, if not all, of that type of flooring has some particle board (maybe mdf, but that's not any better) in it which is essentially ground up wood with a binder pressed together. When it gets wet, it expands like a new sponge. There is nothing you can do to waterproof that well enough to last long term if water is left on it. It may last awhile if you are careful to wipe up any splashes.

The biggest vulnerability is probably the cut edges, but the quality of the joints on some is not that great, either.

To keep the plywood intact, you could use RedGard from www.custombuildingproducts.com. Home Depot carries it as do many tile stores. Another thing would be Ditra from www.schluter.com. Both of those are designed for use with tile. Ditra is waterproof, but you'd need to seal the joints with KerdiBand to make the whole installation waterproof.

I think you'd be better off either tiling the top surface or using a solid surface slab (corian silestone, etc.). The vertical surfaces could be wood but again, the edges are the most vulnerable.

If you decide on tiling, check out www.johnbridge.com

wood + water = NO