We moved into a place needing some work. There is a garage addition behind the house that was partially completed left for years and the plywood rotted. So I have two options the way I see it.
Option 1: replace what needs replacing, and put that line-x style deck coating down.
Option 2: replace the plywood, and finish install decking to match the deck it is attached to, the usual 2x6 boards and such.
Here is my problem, Option 2, what do I put on top of the plywood for waterproofing before I install the decking? I was looking at the roof underlayment, but they all say not to leave exposed for more than 6 months or so. I could put that coating down but it seems pricey to put it down just to cover it up.