Spantex is an excellent coating system for plywood type decks, you want to make sure that you follow the instrutions to the tee to obtain warranty requirements. 1) Ensure that you have the plywood nailed or screwed down properly according to the spantex guidelines. 2) Proper caulking of the joints 3) plywood is at the correct moisture content to apply the basecoat then the finish coat. 4) apply proper thickness of spantex Generally you can get about 10 years out of this system, and yes the product is expensive, but it is a vulcanized rubber product and that is where you cost lies. An economical product similar to spantex is Benjamin Moores M55- Industrial Non skid coating, cost about 1/2 the price and is based on a latex 100% acrylic formulation, It is not as durable as spantex but offers a wider aray of colors and is easier to apply. Good luck on your project!