The answer to 'why is my underlayment damaged' is that there are several common causes, including water leaks, excessive wear and tear, improper installation, and damage from high winds or falling debris. Symptoms of damaged underlayment can include buckling, curling, or cracking of the material, which can lead to leaks and further damage to your roof.
In many cases, damaged underlayment will need to be repaired or replaced by a professional roofing contractor. While some minor repairs may be possible for a homeowner with DIY experience, it's generally recommended to call in a professional to ensure the job is done correctly and to avoid any safety risks. A professional roofer can properly assess the extent of the damage, make necessary repairs, and ensure your roof is properly protected.