Cap flashing, also known as cover flashing or copings, is a protective element used in roofing and construction to prevent water infiltration at the intersections of walls and roofs or other horizontal surfaces. It is typically made of metal, such as aluminum or galvanized steel, and is installed over the top of a wall or parapet to create a waterproof barrier.
The main purpose of cap flashing is to redirect water away from vulnerable areas where two surfaces meet, such as the joint between a roof and a wall. By covering the joint and creating a slope, cap flashing helps to channel water off the roof and prevent it from seeping into the building.
Cap flashing is typically shaped like an inverted "L" and is installed in a layered fashion, overlapping lower layers to ensure proper water drainage. It is commonly used in roofing systems, particularly in flat or low-slope roofs, as well as around chimneys, vents, skylights, and other roof penetrations.
Proper installation of cap flashing is crucial to ensure its effectiveness in preventing water intrusion. It should be securely fastened to the wall and integrated with other roofing components, such as the membrane or shingles, to create a seamless and watertight barrier.
Regular inspection and maintenance of cap flashing are essential to identify any signs of damage or deterioration, such as rust, corrosion, or gaps. Prompt repairs or replacement of damaged cap flashing can help maintain the integrity of the roofing system and prevent water damage to the building.