Cap flashing is a protective metal or membrane flashing installed over walls or parapets to prevent water infiltration.

Cap flashing is a flashing component installed along the top of walls, parapets, or similar vertical surfaces to protect the building from water intrusion. It acts as a cap, shedding rainwater away from vulnerable edges and preventing moisture from penetrating wall assemblies below.

In construction, cap flashing is commonly fabricated from metal materials such as aluminum, steel, copper, or stainless steel, though membrane-based systems may also be used. It is often installed in conjunction with base flashing and counterflashing to form a continuous waterproofing system. Proper slopes, overlaps, and drip edges are critical to effective performance.

Correct installation of cap flashing helps prevent staining, freeze-thaw damage, corrosion, and deterioration of wall materials. Building codes and manufacturer guidelines typically define requirements for attachment, expansion joints, and sealants to ensure durability and long-term weather protection.

Well-designed cap flashing can extend the life of masonry and wall systems by decades by keeping water out of the most exposed areas.

• Aluminum Flashing
• Base Flashing
• Chimney Cap