Growing Ivy

You are right to be concerned. Ivy can damage walls and get under fascia boards. It is so strong once it gets going that it could lift tiles. Can you get to the main stem? If so, cut through it twice - taking a slice out so that it can't re-join. Then the whole plant will start to die and eventually the leaves will fall. If it's a very large plant, it takes a LONG time to die off! This is from personal experience! it is much easier to pull dead ivy off a wall than living strands.

For a few years I allowed ivy to grow up my house wall and just kept cutting out all new growth above a certain height but I got sick of trying to keep on top of it. I also had a berberis in front of it so it was getting to be a (literal) pain to attend to it. When I decided it had to go, I found it easy enough to take live ivy off my house wall, stripping it top down, but I hadn't let it quite get past reachable height in the first place so do what you feel is safest. I wouldn't let it get up into your roof - bad idea.