Unlike typical paper backings that wear away when they're wet, YorkShield 106 PT flashing has a new polymer backing that effectively isolates galvanized joist hangers and fasteners from the decking - and the corrosive effects of ACQ and other treatments - so pressure treated decks look better and last longer. It's the state-of-the-art deck flashing that has it all - the protective qualities you want in copper flashing, plus a non-asphalt adhesive, so it won't stain concrete, vinyl or wood.