I was doing my tear off of my roof, and I noticed a lot of the sheathing and truss ends are rotten. It seems like it only happens where gutters are. It ruins about 6 inches of the sheathing. I bought some certainteed “sand” granulated ice and water. The intsructions say to run it over the drip edge. I’m not sure this would resolve me problem though. Should I go against the instructions and cover the entire fascia and then throw the drip edge on top? It does mention something about running over the fascia (alternative install). Is this what is meant. I’m not even sure that it is the gutters that are the problem. What usually causes rot to occur on the eves?