The answer to 'metal roof sagging' is that the most common causes are improper installation, structural issues, or corrosion of the metal. Symptoms include visible sagging or bowing of the metal panels, gaps or cracks forming, and potential leaks. Solutions can range from reinforcing the roof structure to completely replacing the roofing system.
If the sagging is minor and you feel comfortable working on your roof, you may be able to fix it yourself by adding extra support beams or brackets underneath the sagging sections. However, for more significant sagging or structural problems, it's best to call in a professional roofing contractor to properly inspect and repair the issue.