People with older PCs who keep them outside exposed to the elements, are noticing fine fiberglass hairs sticking up on the roof sheathing. I imagine putting some kind of protectant, wax or otherwise on a disciplined basis, would prevent this breakdown of the sheathing. Which protection is best is surely up for discussion.
I personally do not use any type of protectant, yet not seen the roof hair on our 2007 PC. But our PC is always protected in our garage when at home, with temperatures maintained between 60 and 80 degrees throughout the year.