Which key requirement ensures air penetration is limited on all sides of the building?

The requirement that the system must be continuous is essential for ensuring that air penetration is limited on all sides of the building. A continuous air barrier creates an unbroken seal around the building envelope, effectively minimizing the potential for air leakage. This continuity helps to protect the interior environment from outdoor air infiltration and exfiltration, which can lead to energy loss, increased heating and cooling costs, and potential moisture problems.

While other aspects such as airtightness are also important, the emphasis on continuity underscores the need for a properly integrated design where seams, joints, and transitions in materials do not create any gaps that could compromise the barrier's effectiveness. A continuous system ensures that even if there are fluctuations in air pressure, the integrity of the air barrier remains intact, significantly enhancing the overall performance of the building envelope.

In contrast, criteria such as UV resistance and aesthetic qualities, although relevant in their own contexts, do not directly address the crucial function of limiting air penetration. Thus, understanding the importance of a continuous air barrier is fundamental for successful air barrier installation and performance.