Some of the signs that indicate the decay of the roof and the need to replace it are as follows - Frequent leaks during rain; Curled or missing shingles; Mold on or inside the house; Water damage inside the house; Visible dents on the roof; Bald spots; Light filtering through the attic of the house due to holes; Visible stains as a sign of moss damage; Wear and tear due to age (20 years or more)