The Invisible Key to Building Integrity: Air Tightness
Western Built | Fall 2025
Mohammad Fakoor, PhD, P.Eng., CEA, CPHD, CEM, LEED® AP BD+C | Associate
Air tightness, once an overlooked detail, has become a pivotal factor in modern construction, influencing everything from energy efficiency to indoor air quality. With rising energy costs and increasingly ambitious climate goals, it’s more critical than ever for developers, builders, and property owners to address the impact of air barrier discontinuities, gaps, cracks, and poorly sealed joints in building envelopes. These seemingly minor flaws can lead to significant financial losses and create challenges over time.
At its core, air tightness refers to the control of air leakage through a building’s envelope, the boundary that separates the conditioned interior from unconditioned outdoors. It might sound simple, but the science and logistics behind achieving truly airtight construction are complex, involving both advanced materials and careful coordination during every phase of a building project. Left unchecked, leaks allow precious heated or cooled air to escape, forcing mechanical systems to work harder, driving up energy consumption and a building’s carbon footprint.
But there’s more at stake than utility bills and your conscience. Air leakage can introduce outdoor pollutants, allergens, and moisture, while cold drafts or unexpected heat gain degrade occupant comfort. Moisture, in particular, is a silent threat, capable of undermining insulation, weakening structural components, and even fostering mould. That’s why air tightness is critical for comfort, health, resilience, and sustainability.
The industry gold standard for airtightness
Air tightness testing is a meticulous, data-driven process designed to measure air leakage under controlled conditions. The industry gold standard is the blower door test, which evaluates airflow at a standardized pressure difference, typically 75 Pascals, across the entire building envelope. This isn’t as simple as setting up a fan and checking for drafts; it’s a sophisticated procedure that requires specialized equipment and expertise.
A standard test kit includes high-powered fans, rigid or fabric panels to seal door openings, and precision manometers to measure pressure differences.