The answer to 'why is my underlayment curling shingles' is that improper installation or low-quality underlayment can cause the underlayment to curl, leading to shingle damage. This typically happens when the underlayment is not properly secured, has not been allowed to fully acclimate to the environment, or is of a low-grade material that is not durable enough for the climate.
Curling underlayment can lead to shingles lifting, creasing, and eventually failing prematurely. This not only compromises the roof's appearance but also its ability to properly protect your home from the elements. In most cases, the solution is to remove and replace the damaged underlayment, ensuring it is properly installed and secured according to the manufacturer's instructions.