The answer to 'shingles sagging' is that sagging roof shingles are a common issue that can be caused by a variety of factors. Sagging shingles are typically a sign of an underlying structural problem, such as weak or damaged roof framing, improper installation, or moisture damage. Symptoms may include visible dips or depressions in the roof surface, as well as cracked, curled, or missing shingles.
In many cases, sagging shingles will require professional roof repair or replacement to address the root cause and restore the structural integrity of the roof. DIY repairs may be possible for minor sagging, but it's important to carefully inspect the roof and underlying structure to ensure the problem is not more severe. Homeowners should consider calling a licensed roofing contractor if the sagging is significant or accompanied by other signs of damage.