What is the primary function of flashing in relation to a chimney?

The primary function of flashing in relation to a chimney is to seal roof cutouts from water entry. Flashing is the material, typically metal, that is installed at the junction where the chimney meets the roof. It serves to direct water away from this vulnerable area and prevents moisture from infiltrating the building envelope, which can lead to leaks, rot, and damage over time.

Properly installed flashing creates a watertight seal around the chimney, ensuring that any rainwater or melted snow is channeled away from the roof cutout and down onto the roofing materials. This critical function is essential in maintaining the integrity of the roof and the chimney structure itself, ultimately providing long-term protection against water intrusion and the resulting issues that could affect a building’s safety and comfort.