Quote Originally Posted by zabooda View Post
It is some type of fiber board with a lot resin in it. Hard to imagine it rotting. Warping would be a good possibility.
It was absolutely warped in odd places. There was also some kind of filler like bondo over the deck surface that was about 1/4" thick in places that was cracked and was easy to pry up with a screw driver. We also found the holes in the deck for foam filling covered in this. My guess is it was cracked so badly from being in the sun that water seeped into this "fiber board." Whatever it is, it was completely saturated and soaking wet, so much that I could dig it out with my finger. Also all the foam under the deck was saturated.