What is the purpose of flashing behind stucco at windows and doors?

• A. To hold stucco in place
• B. To divert water away and prevent infiltration
• C. To improve insulation
• D. To provide fasteners

Answer: (D)

Flashing behind stucco at windows and doors is all about directing moisture out of the wall. When water gets behind the outer stucco, this flashing provides a channel that guides that water downward and away from the opening, helping it drain to the exterior rather than seeping into the framing. It protects the rough opening and the building interior from rot and mold by creating a continuous drainage path with the weather-resistive barrier and window/door flashing. This function is why flashing is placed behind the stucco at openings and tied into the surrounding moisture-control system. It’s not primarily meant to hold the stucco in place—that’s the job of the lath and base coat—nor is its main purpose insulation or providing fasteners.