What Is Blower Door Testing – IECC Requirements

Date Published: April 7, 2023

When the 2015 International Energy Conservation Code (IECC) went into effect, blower door testing became a requirement on all new residential builds and remodels. Prior to this code update, blower door testing had been in use for many years. However, this was the first time that it had become mandatory for many new construction projects.

The International Code Council (ICC) saw it fit to address the issues that can occur with too much air leakage in homes. Therefore, this rule was established as a way to increase energy efficiency in new residential builds.

Counties that have adopted the 2015 IECC (or any later edition) require that any new build must have a blower door test performed by a licensed, third-party company. The results of the test must not exceed the region’s maximum leakage rate in order for the building to be deemed IECC-compliant. It is a crucial aspect of the modern building process in the majority of the nation. So what is blower door testing?

A technician conducting a blower door test.

One of our technicians conducting a blower door test.

What is blower door testing?

A blower door test is a procedure that involves using specialized equipment to measure the exact air tightness of a home. Depending on the region of the country, a maximum air leakage rate is defined, and each new home must meet this air tightness level.

This technique is the industry standard and is extremely accurate. Furthermore, it not only helps to determine the level of air leakage, it can actually help you to determine the exact sources causing the air leaks.

How does it work?

A blower door consists of a frame and flexible panel that fit into an exterior doorway. A powerful, variable-speed fan mounts into the frame.

All exterior openings – such as doors, windows, flues vents etc. – are closed off or sealed. The fan is then activated to blow air out of the house, lowering the inside air pressure. The higher outside air pressure then flows in through any unsealed cracks or openings.

Diagram of a blower door test

Image sourced from: https://outlierstudio.com.au

As the fan runs, an integrated pressure gauge measures the pressure differences between the inside and outside of the home, and an airflow manometer and hoses are utilized for measuring airflow.

The equipment used in the blower door test determines a home’s air infiltration rate, which is measured in air changes per hour (ACH). This is the number that is required by the IECC code. For most Colorado municipalities, the air leakage rate for new residential builds or remodels must not exceed 3.0 ACH.

As the blower door fan runs, the technician is able to walk the house, searching for sources of large leaks. Having conducted thousands of tests, our experts know where to look for primary problem areas. Furthermore, we utilize infrared scanning devices to help detect temperature differentials within the home –  a sign that could indicate air leakage.

A specialist can then help to pinpoint the issues, when present, and relay this info to the project contractor in a timely manner. Find out more about common leaks found during a blower door test here.

Do you need a blower door test performed on your project fast? We can help! Visit our blower door service page to learn more and schedule now.

When do you perform a blower door test?

According to the IECC, the test should “be performed any time after creation of all penetrations of the building envelope have been sealed.” Basically, the home should be as close to being complete as possible, with exterior penetrations sealed properly and all the drywall completely installed, before carrying out the a blower door test.

Any leaks caused by an incomplete building envelope could potentially affect the test results. That’s why the full building envelope needs to be sealed before an accurate test can be conducted.

Who can do the testing?

Here at Scott Energy Services, a division of Scott Home Services, LLC, we proudly offer blower door testing services to the Colorado Front Range. We also offer an extensive list of other energy services including duct leakage testing, insulation inspections, air barrier inspections, full energy audits, Manual J,S &D report preparation, as well as full energy rating services including RES-Check reports and HERS ratings. Check out a full list of our services here.

Blower door testing Air Leakage test

Is this required in the county you are building in?

Most of the counties along the Front Range of Colorado have moved to at least the 2015 IECC building code by this time. However, we encourage you contact your municipality in order to confirm which code guidelines your building project must adhere to.

Let our local team of Certified HERS Raters, Certified Rating Field Inspectors and Certified ASHI Home Inspectors work with you to help you meet the IECC energy code requirements in your area.

We can assist your team in determining the best options for the design and construction of your project. Our energy rating services are performed professionally with a focus on accuracy and responsive support.  Here at Scott Energy Services, we are your go-to one-stop-shop” offering Energy Rating Services for Architects, Builders, Contractors, HVAC Professionals, and Homeowners.

For more information visit the Blower Door and Air Leakage page on our website.

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About the Author: George Scott

George founded Scott Home Inspection in 2006, and has grown the business into a multi-inspector firm serving the Colorado Front Range, from Fort Collins down to Colorado Springs. As an ASHI Certified Home Inspector and Certified Energy Rater, George is an excellent resource to help with inspection and energy-related requirements.

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  1. brennerbuilders@outlook.com'
    Brian Brenner March 1, 2017 at 8:02 am

    Hi George, Can a home be too tight and need to have a system installed that mechanically brings in fresh conditioned air to the home.
    What are the passing and failing pressure ratings for new homes? Is it also based on square footage of the home?

    • George Scott March 1, 2017 at 8:18 am

      The IECC code establishes maximum air leakage rates in a home. In Colorado with the 2012 and 2015 IECC that level is 3 air changes per hour when depressurized to 50 pascals. So the blower door runs, depressurizes the home to 50 PA, then we calculate the air changes based upon the volume of the home. At 3 ACH, this is a very tight home, so you definitely then need to have a mechanical ventilation system to bring in fresh air exchanges. The 2012 and 2015 building code requires a mechanical ventilation system when the home is sealed to this air tightness, so plan on installing an HRV or ERV. When we do blower door testing, we help you to find leaks if the home doesn’t pass, we won’t just leave and not help. We’ll use an IR camera to help find the leakage areas so you know what to seal.

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