Exterior Weather Barriers

What Is an Air Barrier?

An air barrier is a material or system intended to limit uncontrolled air movement through a building assembly.

Understanding Air Barriers

Air Barrier: An air barrier is a material or system intended to limit uncontrolled air movement through a building assembly.

Published: June 4, 2026 Reviewed: June 4, 2026 Updated: June 4, 2026 By Exterior Echelon

An air barrier is a material or system designed to limit uncontrolled air movement through a building assembly.

Why It Matters

Air movement can carry moisture, affect comfort, and reduce energy performance. Air control is part of a complete exterior wall or roof assembly.

Common Problems

Common problems include unsealed seams, gaps around windows, unsealed penetrations, and confusing air control with water or vapor control.

Building Codes & Industry Standards

Air barrier requirements depend on assembly type, product selection, and applicable building energy or residential code provisions.

Exterior Echelon Notes

Exterior Echelon explains air, water, and vapor control separately because each layer does a different job.

Air barrier concept in an exterior wall
An air barrier helps control uncontrolled air movement.

Related Terms

Continue learning with connected glossary definitions.

Vapor Barrier

Exterior Weather Barriers

A vapor barrier is a material intended to limit water vapor movement through a building assembly.

Water-Resistive Barrier (WRB)

Exterior Weather Barriers

A water-resistive barrier, or WRB, is a layer behind siding that helps resist water that gets past the exterior cladding.

House Wrap

Siding

House wrap is a weather-resistive barrier installed behind siding to help manage air and water that gets behind the exterior cladding.

Building Envelope

Exterior Construction

The building envelope is the collection of exterior systems that separate the inside of a home from outdoor weather.

Actual Cash Value (ACV)

Insurance & Claims

Actual Cash Value, or ACV, is an insurance valuation that generally reflects replacement cost minus depreciation.

Aluminum Siding

Siding Materials

Aluminum siding is a metal siding material that was commonly used on older homes and can still be found on many exteriors.

Glossary Note

This glossary is provided for general homeowner education. Actual roofing, siding, gutter, window, and exterior remodeling conditions should be evaluated by a qualified contractor before making repair, replacement, or insurance claim decisions.

Frequently Asked Questions

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