The answer to 'when to replace metal roof' is that metal roofs typically last 40-70 years, depending on the quality of the installation and maintenance. Metal roofs are a durable and long-lasting roofing option, but they will eventually need to be replaced as the metal corrodes and the roof system degrades over time. Signs that it's time to replace a metal roof include visible rust, leaks, and significant damage to the roof panels or fasteners.
Homeowners should inspect their metal roof regularly and have it professionally evaluated every 10-15 years to determine if replacement is needed. Proper maintenance, such as regular cleaning and resealing, can help extend the lifespan of a metal roof. However, even well-maintained metal roofs will eventually need to be replaced to ensure the home is properly protected from the elements.