What you should know about air barriers before you start your next project

Air barriers are an essential part of the building envelope, because they help control airflow into and out of a building. But along with controlling airflow, air barriers perform several other functions to help ensure long-term building performance and health, as well as improved energy efficiency. To help make designers aware of air barrier opportunities (and risks), here’s a look at how these systems work in the building envelope, plus some common pitfalls to avoid.

Air barrier basics

Air, vapor and water-/weather-resistive barriers play different roles in the building envelope and have specific definitions:

• Air barrier: A system that prevents uncontrolled airflow between conditioned and unconditioned spaces
• Vapor barrier: An element installed in an assembly to slow the migration of water vapor
• Water-/Weather-resistive barrier (WRB): A material installed on a substrate to prevent bulk water intrusion

In a building envelope system, an air barrier functions as something of a multi-tasker that can simultaneously:

• Manage bulk water
• Control air leakage
• Maximize thermal performance
• Manage condensation
• Limit deterioration

By performing these jobs, an air barrier will protect and serve the building and its occupants in many ways, maybe most notably in terms of reducing building energy use.

Air barriers help boost building energy efficiency

U.S. Department of Energy stats show how energy-intensive buildings can be – they account for 40% of all U.S. primary energy consumed. And 35% of all that energy goes to heating, ventilation, and air conditioning. Fortunately, according to the National Institute of Standards and Technology (NIST), air barriers can reduce building heating and cooling energy demands by 30% regardless of climate zones.

Air barriers protect structures and spaces

Air barriers also guard against threats to long-term building performance. That’s because over time, uncontrolled airflow can lead to scenarios that impact a building’s lifecycle and indoor air quality.

For example, uncontrolled airflow can cause condensation in the insulation and/or other building materials. Wet insulation and materials can freeze and thaw, decreasing the building’s thermal resistance and compromising its long-term integrity and durability. Plus, excess moisture that accumulates in the wall assembly can lead to mold growth, posing risks to indoor air quality and occupant health.

Proper design and installation matters!

When considering an air barrier for your project, you should consider specific architectural design elements, climate and (IBC/IECC) code requirements. Equally important, all system components must be chemically compatible and properly installed.

To help ensure both, it’s smart practice for designers to include a statement in the specification requiring all trades and manufacturers associated with the building envelope to attend a preinstallation meeting. All parties can cover concerns and details about transitions between different systems and the products involved.

Let Henry help before specification starts

Clearly, an air barrier is a key part of the building envelope and subject to several design- and climate-specific requirements. Put another way, there is no one-size-fits-all approach to air barriers. Before designing your next air barrier and building envelope system, don’t hesitate to talk to experienced advisors.

Consider consulting with the experts at Henry® Company – for 80+ years, our solutions have been helping manage the flow of water, air and vapor throughout the building envelope. Today, our Building Envelope Systems® spans a portfolio of compatible solutions designed to help you meet your challenges.