Metal base flashing is not recommended for use with which system?

Metal base flashing is not recommended for use with which system?

• A. Membrane roofing systems
• B. Built-up roofing systems
• C. Metal roofs
• D. Wood shingle roofs

Answer: (A)

Membrane roofing systems require edge details that stay flexible and seal tightly across temperature changes. A metal base flashing is rigid and usually needs fasteners or seams that can pierce or stress the membrane, preventing a continuous, watertight seal. That rigidity can pinch or tear the membrane and create leak paths at the edge, and the metal surface can also be incompatible with the membrane’s adhesives or seam seals. Because these factors undermine the membrane system’s integrity, metal base flashing is not recommended for membrane roofs. Other roof types—like metal, built‑up, or wood shingle roofs—use flashing methods that better match their materials and installation needs.

Membrane roofing systems require edge details that stay flexible and seal tightly across temperature changes. A metal base flashing is rigid and usually needs fasteners or seams that can pierce or stress the membrane, preventing a continuous, watertight seal. That rigidity can pinch or tear the membrane and create leak paths at the edge, and the metal surface can also be incompatible with the membrane’s adhesives or seam seals. Because these factors undermine the membrane system’s integrity, metal base flashing is not recommended for membrane roofs. Other roof types—like metal, built‑up, or wood shingle roofs—use flashing methods that better match their materials and installation needs.