Air Barrier

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Air Barrier

What is Air Barrier?

Air Barrier: A continuous system of materials designed to control airflow through the building envelope.

Description

Air Barrier is a commonly used term in the construction industry. An air barrier is a system of materials—membranes, coatings, sealants, and tapes—installed to form a continuous plane that restricts uncontrolled airflow through walls, roofs, and foundations. It reduces energy loss, prevents moisture‑laden air from condensing within assemblies, and improves indoor air quality. Types include fully adhered sheet membranes, fluid‑applied coatings, and spray‑foam systems. Successful air barriers require continuity at transitions, penetrations, and joints, verified by blower-door testing, to meet airtightness targets (e.g., ≤ 0.4 CFM/ft² at 75 Pa).

FAQs

  • Why install an air barrier?

    To cut heating/cooling loads and prevent hidden condensation.

  • How is air barrier performance verified?

    Blower-door tests measure air changes per hour (ACH50).

  • Are air barriers vapor barriers?

    Not necessarily—vapor permeability varies by product.

  • What materials act as air barriers?

    Self-adhered membranes, fluid-applied coatings, spray foam, or rigid sheathing.

  • Where are air barrier transitions critical?

    At window openings, roof-wall junctions, and slab edges.

  • Does the code require air barriers?

    Yes—IECC and ASHRAE 90.1 mandate them in most climate zones.

  • Who installs air barriers?

    Specialty envelope contractors or trained installers.

Fun Fact

Fun Fact: Canadian researchers pioneered modern air‑barrier science in the 1970s, influencing today’s North American codes.

CSI Code

07 27 00

NAHB Code

720