--- title: How Is A Blower Door Test Performed? description: When you get a blower door test, what number are you hoping for? Find out the factors that determine a good score for ACH testing. image: https://scsfoam.com/hubfs/Article%20Title%20Images/How%20Is%20A%20Blower%20Door%20Test%20Performed.jpg --- [Skip to main content](https://scsfoam.com/blog/how-blower-door-tests-are-performed#maincontent) [(717) 895-3498](tel:7178953498) [![South Central Services Insulation](https://scsfoam.com/hs-fs/hubfs/branding/Website%20Logo%20Classic.png?width=900&height=300&name=Website%20Logo%20Classic.png) ![South Central Services Insulation](https://scsfoam.com/hs-fs/hubfs/branding/Website%20Logo%20White.png?width=900&height=300&name=Website%20Logo%20White.png)](https://scsfoam.com/) [Our Service Areas](https://scsfoam.com/our-services-areas) Pricing - [Our Rates](https://scsfoam.com/our-rates) - [Calculators](https://scsfoam.com/pricing-calculators) - [Financing](https://scsfoam.com/financing-options/) - [Rebates](https://scsfoam.com/rebates) [Our Team](https://scsfoam.com/our-team) Services - Residential Insulation - [Attic Insulation](https://scsfoam.com/attic-insulation) - [Basement Insulation](https://scsfoam.com/basement-insulation) - [Crawl Space Repair](https://scsfoam.com/crawl-space-encapsulation) - [Commercial Spray Foam](https://scsfoam.com/commercial-spray-foam/) - [New Construction Insulation](https://scsfoam.com/new-home-construction-insulation/) - [Pole Building Insulation](https://scsfoam.com/pole-building-insulation) - [Air-Sealing](https://scsfoam.com/air-sealing) - [Blower Door Tests](https://scsfoam.com/blower-door-tests) [Our Products](https://scsfoam.com/our-products) Learning Center - [Learning Center](https://scsfoam.com/learning-center) - [Downloadable Resources](https://scsfoam.com/downloadable-resources) - [FAQ](https://scsfoam.com/faq/) Open Search [Get A Quote](https://scsfoam.com/contact/) Search for topics or resources Enter your search below and hit enter or click the search icon. 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March 28th, 2025 2 min read By [Kilian Agha](https://scsfoam.com/blog/author/kilian-agha) ![](https://scsfoam.com/hubfs/Article%20Title%20Images/How%20Is%20A%20Blower%20Door%20Test%20Performed.jpg) How does blower door testing work? What exactly happens when you sign up for a blower door test? South Central Services is certified to perform blower door tests. We administer these tests in and around Greencastle, Pennsylvania. By the end of this article, you’ll understand how blower door tests are performed. ## Blower Door Tests Are Administered By Certified Professionals. There is a unique certification process to perform blower door tests. A valid blower door test should only be performed by a qualified, certified professional. These professionals may work with organizations like the [Building Performance Institute (BPI)](https://www.bpi.org/) and the [Air Barrier Association of America (ABAA).](https://www.airbarrier.org/) ## The Test Begins By Collecting Data. Once you've made your appointment with a qualified technician, they will arrive with their equipment. Before anything else, the technician will collect data from the house and weather conditions at the time of testing. Using collected data, the technician will calculate the overall cubic feet of the house. > The cubic feet of the home includes anything within the [thermal envelope](https://scsfoam.com/blog/spray-foam-insulation-glossary#building-envelope-definition). This total is entered into the software. ## The Test Continues With Installing A Fan. Installing the blower door fan is the next step in a blower door test. Now that the technician knows the cubic feet of the home, they can test the house at a specific pressure. This will reveal how leaky the home is. Most commonly, the fan is installed in the main exterior door of the house. Other openings in the thermal envelope are kept the way they would be while you’re living there. This could include: - Other doors - Windows - Chimney ![A technician from South Central Services completing a blower door test on a new construction home.](https://scsfoam.com/hs-fs/hubfs/Article%20Graphics/Performing%20A%20Blower%20Door%20Test.jpg?width=533&height=400&name=Performing%20A%20Blower%20Door%20Test.jpg) ## That Fan Removes Or Adds Air To The Home. Once the fan is in place, the technician will turn on the fan. Depending on how the fan was set up, it will either blow air into the home or pull air from the home. If the fan blows into the house, it increases the air pressure inside. If air is pulled from the home, the house is depressurized. As the air pressure changes, any air leaks in the home allow air to enter or exit. This portion takes approximately 20 minutes to complete. ## Air Changes Are Measured With Specialized Equipment. The technician measures the exact air exchange while air passes through any cracks and crevices in the thermal envelope. This exchange is measured as air changes per hour (ACH). The technician also tracks the amount of air moving through the fan (CFM). These tests are incredibly precise and require carefully calibrated equipment. If the instruments are not properly cared for, the results could be inaccurate. ## Results Are Shared Through An Official Report. Once your blower door test is concluded, the technician will share the results with you. At South Central Services, we will provide you with an official report and discuss the score with you. > In our service area, under the current building code, [any score at or below 3 ACH is considered passing](https://scsfoam.com/blog/how-to-pass-blower-door-testing). A score higher than 3 ACH is considered a fail. You shouldn't have any additional concerns as long as your home passes the blower door test. You'll have the necessary documentation to prove the air changes per hour (ACH) are at or below the threshold. ![A spray foam insulation crew member installing professional can foam as an air-sealing product.](https://scsfoam.com/hs-fs/hubfs/Article%20Title%20Images/Best%20Air%20Sealing%20Products.jpg?width=533&height=400&name=Best%20Air%20Sealing%20Products.jpg) If your home does not pass the blower door test, you'll need to seal up problematic air leakage. After the air leakage has been addressed, you can schedule another blower door test. In our experience, houses that fail usually have air leakage throughout the thermal envelope, rather than just one problem area. ## The Bottom Line About How Blower Door Tests Are Administered Certified technicians perform blower door tests. A blower door test can be completed within an afternoon. The technician will install a fan and run that fan, measuring the air it moves and the air changes in the home. Specialized instruments ensure accurate results. Now that you understand how blower door tests are performed, your next step is to: - [Learn how much blower door testing costs](https://scsfoam.com/blog/blower-door-test-cost) - [Discover the best air-sealing products](https://scsfoam.com/blog/best-air-sealing-products) - [Request a blower door test from South Central Services](https://scsfoam.com/blower-door-tests) [![SCHEDULE MY TEST](https://no-cache.hubspot.com/cta/default/39735758/interactive-183818988804.png)](https://scsfoam.com/hs/cta/wi/redirect?encryptedPayload=AVxigLKxUJQ8p2RIfUUdwD8n79tQBRbqhufPxXtdG5SYXzGyUG3hY63yWAOjVTY6AvXKgpxGgD%2FLfaGrHyl8jWq7o%2FB%2FCioHrHFFYjKklnyCHl%2FbI37u9hMv9joipkXZJ2o%2BnGmAFFg5txzH2Hnzoru7NrSiS8nMLuoL88kHfWSu1cPxbsdCUgg7dAK9QJQcM3E5Vw%3D%3D&webInteractiveContentId=183818988804&portalId=39735758) *Disclaimer: While we strive to publish information accurate to building science, local building codes and standards supersede our recommendations.* [Kilian Agha](https://scsfoam.com/blog/author/kilian-agha) Kilian has co-owned and operated South Central Services for 8 years. He is passionate about community involvement. In his spare time, he enjoys being with his family, playing ice hockey, and going fishing with friends. Topics: [ACH Testing](https://scsfoam.com/blog/topic/ach-testing) Don't forget to share this post: ## Related Articles ### [What Is A Blower Door Test Used For? May 16th, 2025|2 min read](https://scsfoam.com/blog/what-are-blower-door-tests-used-for) ### [How To Pass A Blower Door Test April 18th, 2025|3 min read](https://scsfoam.com/blog/how-to-pass-blower-door-testing) ### [Are Blower Door Tests Required? December 20th, 2024|2 min read](https://scsfoam.com/blog/are-blower-door-tests-required) ### [What Does A Blower Door Test Do? December 2nd, 2024|2 min read](https://scsfoam.com/blog/what-does-a-blower-door-test-do) ### [How Much Does A Blower Door Test Cost? 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