Which of the following is an example of air barrier accessories?

Air barrier accessories play a crucial role in creating a continuous air barrier system, essential for energy efficiency and moisture control in buildings. The correct option includes flashing, sealants, and transitions, which are all critical components that ensure the integrity of the air barrier.

Flashing helps redirect water away from vulnerable areas, preventing moisture intrusion, which can compromise the air barrier's effectiveness. Sealants are used to fill joints and gaps in the building envelope, ensuring there are no unintended openings that could allow air leakage. Transitions refer to the connections between different building elements where air barriers must be carefully detailed to maintain continuity and performance.

These accessories work in concert to prevent air movement, thus promoting energy efficiency and enhancing the overall comfort of the interior environment. In contrast, the other options describe materials or elements that do not specifically serve the function of forming an air barrier. For example, insulation is primarily used to resist heat flow, while structural supports pertain to the building's stability. Similarly, walls and ceilings contribute to the overall structure but do not encompass the necessary components for effective air barrier systems, and foundation materials pertain to the base of the structure and are not classified as air barrier accessories.