The answer to 'when to replace roof installation' is that most roofs typically last between 20-30 years, depending on the roofing material and local climate conditions. As a roof ages, it becomes more susceptible to leaks, damage, and inefficiency, so it's important to monitor its condition and replace it when necessary.
Signs that it may be time to replace your roof include visible wear and tear, curling or cracked shingles, missing granules, and frequent leaks or water damage. If your roof is approaching 20 years old or is showing significant signs of aging, it's a good idea to have a professional roofing contractor inspect it and provide recommendations on whether a replacement is needed.