What must be installed at the intersection of chimneys or other masonry construction with frame walls?

Flashing is critical at the intersection of chimneys or other masonry construction with frame walls because it serves as a waterproof barrier. Masonry and frame structures have different expansion and contraction rates, and moisture can easily penetrate the seams where they meet. Flashing redirects water away from these vulnerable areas, preventing water intrusion that could lead to mold, decay, or structural damage. Installing flashing ensures that any water that accumulates is channeled away, protecting both the masonry and the frame walls from water-related issues.

Insulation, sheathing, and joint compound do not provide the same protective functions against moisture at this intersection. Insulation is primarily used for energy efficiency, sheathing provides structural support and an additional layer of weather resistance, while joint compound is used for finishing drywall seams. Therefore, flashing is essential for maintaining the integrity and longevity of building structures at these junctions.