What is the primary purpose of roof flashing around penetrations?

• A. To provide decorative trim
• B. To insulate the attic
• C. To strengthen the roof deck
• D. To seal the gap around penetrations and direct water away from penetrations

Answer: (D)

The main idea is to seal gaps around penetrations and direct water away from them. Flashing creates a waterproof barrier where pipes, vents, chimneys, or other through-roof openings meet the roof surface, and it guides any moisture toward the outside rather than letting it seep into the roof deck. When installed properly, flashing integrates with the shingles to shed water off the roof and into the gutter system, preventing leaks at those openings. This is different from decorative trim, which doesn’t stop water intrusion, insulation which controls temperature, or structural strengthening of the roof deck, which is not the purpose of flashing.