The answer to 'why is my metal roof curling shingles' is that metal roofs can sometimes cause the adjacent asphalt shingles to curl or buckle over time. This is typically due to the different thermal expansion rates between the metal and asphalt materials. As the metal roof heats up and expands in the sun, it can put stress on the shingles and cause them to curl upwards at the edges.
Other common causes of metal roof-induced shingle curling include poor installation, lack of proper ventilation, and the metal roof reflecting too much heat onto the shingles. Curling shingles can lead to leaks, reduced lifespan, and an unsightly appearance.