A waterproof barrier installed beneath building materials to collect and redirect water away from vulnerable areas and prevent moisture damage.

Pan flashing is a waterproof barrier installed beneath building materials to collect and redirect water away from vulnerable areas, preventing moisture infiltration and water damage to building structures. This critical component of building envelope systems creates a continuous, sloped surface that channels water to designated drainage points, typically at the base of walls, around windows and doors, or beneath roofing materials. Pan flashing is essential for protecting buildings from water damage by providing a secondary line of defense when primary weather barriers fail or when water penetrates through joints, cracks, or other openings in the building envelope.

Pan flashing is installed in various building applications including window and door installations where it collects water that may penetrate behind the primary sealants and redirects it to the exterior, wall systems particularly at the base of masonry veneer or stucco walls where it prevents water from reaching the structural framing, roofing applications such as beneath roof membranes at parapets, penetrations, and low-slope areas, deck and balcony construction where it protects the structure beneath from water infiltration, and specialty applications such as behind exterior cladding systems, around mechanical penetrations, and at building expansion joints. Each application requires specific design and installation techniques to ensure effective water management.

The materials and construction of pan flashing include various waterproof materials such as sheet metal including copper, aluminum, stainless steel, and galvanized steel that provide durable, long-lasting protection, synthetic membranes such as EPDM rubber, TPO, and modified bitumen that offer flexibility and ease of installation, self-adhering membranes that provide excellent adhesion and conformability to irregular surfaces, and liquid-applied membranes that can be applied in place to create seamless waterproof barriers. Material selection depends on the application, environmental conditions, compatibility with adjacent materials, and expected service life.

Fun Fact: The concept of pan flashing dates back to ancient Roman architecture, where lead sheets were used to create waterproof barriers beneath roof tiles and around building openings, establishing principles still used in modern flashing systems today.

• Aluminum Flashing
• Base Flashing
• Cap Flashing