What does the term "fishmouth" refer to in roofing materials?

The term "fishmouth" specifically refers to a defect in roofing materials characterized by a seam that has become wrinkled, resulting in an opening. This defect typically occurs in applications such as roofing membranes, where improper installation or movement can cause the material to pucker or lift, resembling the shape of a fish's mouth. This issue can lead to significant problems, such as water infiltration, which can compromise the integrity of the roofing system and underlying structures.

Understanding this term is essential for roofing professionals, as it highlights the importance of proper installation techniques and ongoing maintenance to prevent such defects, ensuring the longevity and performance of the roofing materials used.