What does the concept of 'air barrier transition' refer to?

The concept of 'air barrier transition' refers specifically to areas where different materials join. This is crucial for maintaining an effective air barrier system because these transition points are often the most vulnerable areas for air leakage. When materials change, such as where a wall meets a different construction element, it can create gaps or inconsistencies that allow air to flow through. Properly sealing these transitions is essential to prevent air infiltration and exfiltration, thereby ensuring the thermal and moisture performance of the building envelope is upheld. Addressing these critical junctions helps to maintain the integrity of the air barrier, ensuring that it functions effectively throughout the structure.

The other options do not capture the broader concept of air barrier transitions in a way that emphasizes their importance in maintaining the overall air barrier effectiveness. For instance, sealing joints between windows and frames is a specific application but doesn’t encompass the broader range of material transitions, while gaps between the exterior and interior walls, as well as between the roofline and top plate, might refer to particular scenarios that occur at transitions but don’t fully define the concept itself.