The answer to 'how do I know if my roof needs to be replaced' is that your roof likely needs replacement if it is over 20 years old, has missing or damaged shingles, or is showing signs of leaks or water damage. Regular inspections by a professional roofing contractor can help identify issues early and determine if a full roof replacement is necessary.
Some common signs that your roof needs to be replaced include curling, cracked, or missing shingles, excessive granule loss, visible damage to the roof deck or flashing, and leaks in the attic or ceilings. Older roofs may also simply be at the end of their lifespan and need to be replaced for optimal protection of your home.