Proper flashing around chimneys, vents, and walls is essential to divert water

https://ericknecb126.tearosediner.net/how-to-tell-when-it-s-time-to-replace-your-roofwarping-or-curling-roof-shingles

Proper flashing around chimneys, vents, and walls is essential to divert water, preventing seepage at high-risk transitions and penetrations.