Flashing grade adhesives are typically used to bond membrane flashings to which substrate?

• A. Vertical substrates
• B. Horizontal substrates
• C. Concrete surfaces
• D. Wood substrates

Answer: (A)

Flashing grade adhesives are used because they are built to bond membrane flashings to vertical surfaces where water runs down and wind or gravity can pull at the edge. The bond on a vertical plane must be strong, durable, and flexible enough to handle temperature changes and movement, so the flashing stays attached and watertight around wall transitions, parapets, and similar surfaces. While flashings can interact with other substrate orientations, the adhesive’s design emphasizes securing to vertical substrates, making that the best-fit choice.