I just a had a new house built with a covered porch (8'x 58'). My builder used T&G flooring (pressure treated and kiln dried - supposedly). It is over a crawl space with crawl space vents and a vapor barrier. He installed it the same day the wood was delivered, and then coated the tops and ends with a sealant. It didn't take long for the boards to cup and start separating. About 4 months later, the cupping did start to lessen, for whatever reason. He sanded the entire thing down and resealed with a minwax product (and he only brushed it on around the edges, rolling it on everywhere else - 3 coats done that way.

Question: I now know that he probably should have sealed all sides of each board PRIOR to installing them. What is the best way to extend the life of my porch floor, considering how it was installed? Should I go underneath and seal the bottom (no light under there)?