Which of the following is not a common problem with built-up roofing systems?

Oil-canning is not typically classified as a common problem associated with built-up roofing systems. Instead, it is a term more commonly related to metal roofing, where the surface appears to bulge or ripple due to thermal expansion and contraction.

In contrast, blisters are a well-known issue in built-up roofing, resulting from trapped moisture or air under the layers of roofing material. Alligatoring refers to the surface cracking that resembles the skin of an alligator, often due to aging and UV exposure. Ridging, characterized by a raised portion of the roofing membrane, can occur due to inadequate application or substrate issues. Understanding the specific problems associated with built-up roofing systems helps in diagnosing and maintaining these types of roofs effectively.