What is an Air Barrier?

Photo Credit: Tyvek

Air barriers are one of the most essential components of a building’s envelope. The building envelope, which includes exterior cladding, insulation, and air barriers, plays a critical role in the thermal performance, energy efficiency, moisture control, and indoor air quality of a building. 

In this article, we will delve into the different aspects of air barriers, including how they work, types of materials used, installation techniques, testing methods, building codes, standards and their contribution to sustainable building design.

If you’re looking for quick answers to questions you may have regarding air barriers, check out our FAQ below.

Let’s get started.

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What is an Air Barrier?

An air barrier is a material or system designed to prevent air leakage into or out of a building.

What is air leakage, and why does it matter?

Understanding Air Leakage in Buildings

Air leakage is a significant problem in buildings, which can cause wasted energy, increased utility bills, and reduced indoor air quality. 

Buildings account for about 40% of all energy consumption in the United States, and air leakage is a major contributor to this wastage. 

Air leakage occurs when air enters or exits a building through gaps, cracks, and openings in the building envelope.

Commercial Air Barrier Wrap

Photo Credit: 3M

How Air Barriers Prevent Air Leakage

Air barriers are designed to prevent air leakage by reducing the airflow resistance. They are installed on the building’s exterior, interior, or within the wall assembly to create a continuous layer that restricts the movement of air in and out of the building. 

This reduces the amount of uncontrolled air movement in the building, which can help improve energy efficiency, thermal performance, and indoor air quality.

The Impact of Air Barriers on Energy Efficiency and Indoor Air Quality

Improving air sealing and insulation can reduce energy use by 18-38% in commercial buildings, according to a study by the National Renewable Energy Laboratory. 

Air barriers play a crucial role in reducing the amount of uncontrolled air movement, which can result in significant energy savings. 

Additionally, poor indoor air quality can lead to health problems, according to the Environmental Protection Agency. 

Properly installed air barriers can help prevent the infiltration of pollutants and improve indoor air quality.

Let’s talk about the different materials you can use for a successful air barrier.

Types of Air Barrier Materials

There are several types of materials used for air barriers, including sprayed polyurethane foam, self-adhered membranes, mechanically fastened membranes, fluid-applied membranes, and rigid foam insulation. 

Each material has its pros and cons, and several factors should be considered when choosing an air barrier material, such as cost, durability, vapor permeability, and compatibility with other building materials.

After you choose your barrier material, it’s time for installation.

tyvek Air Barrier

Photo Credit: Tyvek

Installation Techniques

Proper installation is critical to the performance of air barriers. The installation technique should be compatible with the building system and materials used, and all penetrations and transitions should be appropriately addressed. 

Understanding the interaction between air barriers and other building systems, such as the HVAC system and ventilation, is also crucial for optimal performance.

After installation, it’s important to test to make sure that your barrier works properly.


Testing air barriers is essential to ensure building performance and compliance with building codes and standards. 

There are several testing methods and standards available, such as the ASTM E2178 and E2357, which measure air leakage and airflow resistance. 

Air barrier testing can help identify areas of air leakage, which can be corrected to improve the quality of your barrier.

Testing also helps to ensure that you’re compliant with code.

Codes and Standards

The International Energy Conservation Code (IECC) requires the use of air barriers in all commercial and residential buildings in the United States.

Compliance with building codes and standards is essential to ensure that the air barrier system is designed and installed appropriately. 

Understanding the impact of codes and standards on air barrier design and installation is critical for optimal building performance.

Complying with code also means your building is much more sustainable.

Why Air Barriers are important

Photo Credit: ICC NTA


Air barriers play a vital role in sustainable building design by reducing energy consumption and improving indoor air quality. 

Using sustainable air barrier materials, such as recycled content and low volatile organic compound (VOC) products, can also contribute to overall building sustainability.


Air barriers are essential components of a building’s envelope that play a critical role in the thermal performance, energy efficiency, moisture control, and indoor air quality of a building. Proper air barrier design and installation are critical to optimizing

If you’re in need of an air barrier, or want to learn more, contact us.


Why are Air Barriers Important?

Air barriers are important because they can help improve energy efficiency, indoor air quality, and moisture control in buildings. They also help ensure compliance with building codes and standards.

How do Air Barriers Work?

Air barriers work by preventing the movement of air through building assemblies. They are typically installed on the exterior of the building envelope to create a continuous barrier.

What are the Most Common Materials used for Air Barriers?

Common materials used for air barriers include spray foam insulation, house wrap, sheathing, and self-adhesive membranes.

How are Air Barriers Installed?

Air barriers are typically installed during the construction phase of a building. They can be installed as part of the building envelope, or as a separate system on the interior or exterior of the building.

How do Air Barriers affect Indoor Air Quality?

Air barriers can help improve indoor air quality by reducing the infiltration of outdoor pollutants and allergens into the building. They can also help prevent the growth of mold and mildew by controlling moisture levels.

What is Air Barrier Testing?

Air barrier testing is a process used to measure the airtightness of a building envelope. It can help identify areas of air leakage and ensure that the air barrier system is functioning properly.

Are Air Barriers Required by Building Codes?

Yes, air barriers are required by building codes in most jurisdictions in the United States. The International Energy Conservation Code (IECC) requires the use of air barriers in all commercial and residential buildings.

Can Air Barriers help Reduce Energy Costs?

Yes, air barriers can help reduce energy costs by reducing the amount of energy needed to heat and cool a building. They can also help prevent moisture damage, which can lead to costly repairs.

Air there any Drawbacks to using Air Barriers?

One potential drawback to using air barriers is that they can limit the ability of a building to “breathe,” which may affect indoor air quality. However, this can be addressed by ensuring that the building has adequate ventilation.

Additional Resources

4 Best Practices for Commercial Construction Efficiency

How to Control Cost in Commercial Construction

How to Save Energy in your Commercial Building