In proper chimney flashing installation, how far should the flashing extend over the shingle surface?

In a proper chimney flashing installation, the flashing should extend over the shingle surface by at least 4 inches. This is critical for ensuring adequate water drainage and preventing leakage around the chimney. Flashing is designed to channel water away from the joint between the chimney and the roof, and extending it sufficiently over the shingles helps to create a tight seal that reduces the possibility of water infiltration.

By adhering to the 4-inch guideline, the flashing is better positioned to manage water runoff from the roof, directing it away from the chimney base. This practice helps protect the roof structure from moisture intrusion that could lead to wood rot, mold growth, and other water-related damage. Proper installation also takes into account factors like the slope of the roof and the type of roofing material used, but the 4-inch standard provides a solid foundation for effective water management in chimney flashing applications.