Material for seat base that will not rot?
#12
The problem with PVC is that it has poor structural strength. If the seat base is supported well from underneath then it'll be fine, if not move on, it will also deform from gravity if left unsupported long enough. I have no idea what the specific structure is for the seat you're working on, maybe some more info would help. I work that that garbage all day sometimes if we're trimming out houses.