What is the name of the thin material used in mortar joints to prevent water penetration in masonry?

Flashing is specifically designed to prevent water penetration in masonry by directing moisture away from joints and vulnerable areas. In masonry construction, water can seep through mortar joints, leading to structural issues over time. Flashing is typically placed behind or above masonry veneer and is made from various materials, such as metal or plastic, ensuring a reliable barrier against water intrusion.

This approach to moisture management is crucial because it helps safeguard the integrity of the structural elements of a building. While membranes, sealers, and sheathing can also play roles in moisture protection, they serve different functions within the construction process. Membranes are more often used as waterproof barriers on horizontal surfaces, sealers are applied to surfaces to reduce porosity and absorbency, and sheathing refers to materials that provide structural support and insulation to walls and roofs. Therefore, flashing is the most relevant choice for preventing water penetration specifically at mortar joints in masonry.