Unfortunately, some people don't realize the importance of the felt paper underlayment and just "reuse" what is there when they install a new roof.
Here are some horror stories:
"I didn't realize that I needed to remove the felt paper underlayment when I installed my new roof. A few months later, I started noticing water spots on the ceiling. It turns out that there was a leak on the side of the roof, and the water was seeping through the felt paper and into my house." - Jason Edwards.
"I had a sketchy roof installer who said that he could install my new roof without removing the felt paper. I should have known better, but I was just trying to save a few bucks. A few weeks after he installed the roof, it started to rain, and all of my vent pipes started leaking. I had to call him back out to fix it, and I ended up paying twice as much as I would have if I had just removed the felt paper in the first place." - Carol Smith.
"After Hurricane Ida, I let some out-of-towners replace my roof. They didn't remove the felt paper underlayment and just put a new roof on top of it. A few months later, my roof started leaking. I had to call Better Built Contractors to fix the problem, and I ended up paying a lot more than if I had just removed the felt paper myself.
Don't get me wrong, Gage and his team are the best contractors I've ever worked with, but it would have been a lot cheaper if the out-of-towners had just done it the right way." - Justin Marchand