What role do windows and doors play in air barrier systems?

Windows and doors are critical components in air barrier systems, and they must be sealed and flashed properly to maintain the integrity of the air barrier. Proper sealing prevents air leakage around these transitions, which can lead to energy loss and reduced comfort within a building. If windows and doors are not adequately integrated into the air barrier system, they can become weak points where air can infiltrate or escape, undermining the effectiveness of the entire system.

Flashing is particularly important because it directs water away from the building envelope and helps to seal potential gaps that could allow air movement. Therefore, ensuring that these elements are correctly installed and sealed is essential for optimizing energy efficiency and indoor air quality, while also contributing to the durability of the building structure. The other options do not accurately reflect the necessary role of windows and doors in maintaining an effective air barrier system.