The answer to 'why is my flashing curling shingles' is that the flashing around your roof is likely not properly installed or has become damaged over time, causing the shingles to curl. Flashing is the thin metal or plastic material used to create a waterproof seal around roof penetrations, edges, and joints. If the flashing is not installed correctly or has deteriorated, it can allow water to seep in and cause the shingles to curl and lift up.
Common causes of curling shingles due to flashing issues include improper installation, exposure to the elements, and normal wear and tear over time. Symptoms include visible curling or lifting of the shingles, water stains, and potential leaks. To fix the problem, you'll need to inspect the flashing and either repair or replace it as needed. This is generally a job for a professional roofer, as improper flashing installation can lead to serious water damage if not done correctly.