Where should flashing be installed to prevent water penetration in chimneys?

Flashing should be installed where the chimney stack meets the roof because this is a critical junction that often exposes the structure to water infiltration risks. Proper flashing at this point creates a protective barrier that directs water away from the chimney and onto the roof surface, preventing it from seeping into the interior of the home. It is essential for the flashing to be integrated with the roofing materials to ensure continuous waterproofing at this vulnerable intersection.

If the flashing were installed at the base of the chimney, at the interior, or in the attic space, it would not effectively address the primary area where water runoff from the roof can flow into the chimney structure, leading to potential leaks and water damage within the home. This highlights the importance of placing flashing at the correct location to ensure proper drainage and protection against water intrusion.