I researched for weeks on what would be the best way to reseal around my fairly large chimney that has been capped off. While I coated the cap with Masterseal by BASF I kept hearing about this product from different friends and a couple of places online. One reviewer said he had spilled some on his driveway 10 years ago and it still shed water! So i sealed up the cap with the Masterseal and then I ordered a gallon of this to spray in a garden sprayer from the top up all the way around. I was worried that one gallon might not be enough but I had enough to do three coats and also a smaller chimney from my furnace. I did go around a use a steel brush to get ride of any moss before I started. The product seemed to penetrate well and if it holds up for 10 years will have been well worth the money! Time will tell.