BPI Multifamily Building Operator (MFBO) Practice Exam 2026 - Free BPI MFBO Practice Questions and Study Guide

A pressure barrier defines the boundary where indoor and outdoor air meet under a controlled pressure difference. By maintaining a higher or lower pressure inside relative to the outside, the building limits air exchange through openings, helping keep outdoor contaminants, odors, and humidity from infiltrating the indoor space or, in some cases, containing indoor contaminants from escaping. This concept is about directing airflow between the indoors and outdoors to protect indoor air quality and energy performance. It isn’t about separating water vapor or heat; those are addressed by humidity control and thermal management, respectively.