Plywood (100% waterproof) 

Advantages: 

A) 100% environmental product, 
B) 100% water proof, fungus resistant, vermin resistant, 
C) 100% free from cement for slab, 
D) 100% not require form oil for slab, 
E) 100% 1 year guarantee on skin does not peel off, 
F) 100% save cost- not to buy plywood for the next project.