Features VELUX flashings integrate with the roof covering to provide a weathertight finish around the window. They are compatible with virtually any type of roofing material, from standard covers such as slate and tiles through to corrugated sheeting or even thatch. Flashings are designed to sit under the roofing materials. The water from the roof is then collected in the built-in guttering system. The gutter overlaps a second section of the flashing to help the water flow smoothly down the side of the window.