A render stop bead is used in external rendering systems to form and protect the lower edges of rendered walls, typically installed above doors, windows, and at damp proof course (DPC) levels. Its unique profile creates a sloped or gently angled lip that forces water running down the render to drip off rather than running back toward the wall or substrate underneath the bead. This feature helps prevent moisture from penetrating the render, reduces damp issues, and avoids cracking caused by trapped water.