Extends you outside deck structure by years using Deck Flask! And it's easy and cheaper than other protective treatments.
product is easy to use and perfect for my outside deck and the stringers. My previous deck (around a pool) barely lasted 12 years because I did not use this Flash Barrier. I've had the under-structure of my decks last over 20 years when using Deck Flash...so lesson learned. Deck Flash does extend your deck structure by years, especially when it's a free-floating deck around a pool.
Use alcohol or the like and be sure the surface is prepped and clean as possible, otherwise it doesn't stick to the surface and just causes another gap for trapping moisture.