Exterior Preserver (very wet!)

[FirlandsFarmer]

I want to build a base for an inflatable jacuzzi. What would be the best preserver to put on the wood to protect it from an obviously wet environment and should I use something different for the underside that will be in contact with a layer of hard foam insulation panels placed on patio paving stones and get wet from the general mustiness of water travelling under when raining and not dry as quick because the sun and wind will not be able to get to it.

 

[screwpainting]

Build it in Medite Tricoya MDF. brilliant stuff, its water proof, rot proof and stable, google it.