In repeated two-point testing, which pressure point do standards typically require testing first?

In repeated two-point testing for whole-building airtightness, standards typically require starting with high pressure points. This approach is based on the understanding that testing at high pressure roots out potential air leakage paths more thoroughly. High pressure differences can often reveal leaks that are not as easily detected at lower pressures due to the increased force driving air through any openings or cracks present in the building envelope.

By beginning at high pressure points, the testing process helps ensure that the most significant leaks, which tend to allow the greatest airflow, are identified and addressed first. This sequence is crucial in developing an accurate representation of the building's airtightness performance. Following this initial test at high pressure, subsequent tests at lower pressure can then confirm the findings, providing a more comprehensive understanding of the building’s air sealing effectiveness throughout various conditions.