Understanding Blower Door Testing

Back in 2012, the International Residential Code (IRC) put forth a revised set of requirements and building code standards as they do every year. 2012 marked a new era in building codes when the airtightness of home came under scrutiny.

What is the airtightness of a home? How is it measured?

Essentially, airtightness is measured to determine how well the house was built to minimize risk of moisture intrusion and provide enhanced stability for energy efficiency. The airtightness of a home is measured by how drafty the home is—how much air is able to escape through seams, seals, and entryways. It is measured through a special pressurization device hooked up to a machine called a blower door. This test measures the difference between the outside air pressure and air pressure found indoors. The difference is the measurement of airtightness in the home.

How does a blower door test work?

A blower door test is conducted with a unique looking machine that is installed in the entryway of a home, usually the front door. It has a powerful fan that, once turned on, pulls air from inside the home and pushes it outside, essentially creating a vacuum. Scientifically speaking, nature will attempt to fill a vacuum, and it does this in a depressurized home by pushing air through any cracks in the home’s structure. As the fan runs the air to the outside, an attached device, called a manometer gauges the air pressure inside and out of the home. A comparison of the air pressure and how much the fan has to work to maintain the pressure between the two tells the inspector how well constructed the home is. The pressure is measured in a unit called CMF50. Understanding the numbers on a manometer can be difficult to explain but the result should be equal to or less than the square footage of a home. Less than is preferable. So, a home that is 2,000 square feet should have a 2,000 CMF50 or less.

When should a blower door test be done?

The most common times for a blower door test to be conducted is during the building phase of a new home or building. This allows time for builders to reassess their construction and correct any flaws before the completion of the home.  A blower door test may be conducted by a building or home inspector when the building is very old, and renovations are being considered. Acusystem Inspections now offers blower door testing to residential and commercial clients for both new construction and already built structures. Contact us today to learn more about the blower door process or to schedule your inspection and testing.

Why Would My House Need Blower Door Testing?

To fully address this question, we’ll first discuss what a blower door test is and then why your home may need one done. Blower door testing is essentially a test that determines how airtight your home is. Seems pretty self-explanatory, but why would your home need blower door testing? Why does it matter how airtight your home is? For starters, no one has ever liked a drafty house. It usually means there are potential other issues such as water intrusion, mold, and decay of building materials. How so? Well, the air is full of moisture—and in Florida, with higher humidity than many other places, even more so. So, if air is getting into your home, that means the moisture it is bringing in with it is settling on your walls, on your floors, in your HVAC system, on your ceiling, your attic…you get the picture. Over time, mildew and bold begin to grow, usually beginning in hard to notice areas. When mold is able to grow unchecked, it slowly eats away at the building materials, causing them to decay. As an added downside, drafty homes also consume extra energy just to maintain the correct temperature and because air is constantly leaking, its not very comfortable temperature-wise. So, blower door testing is just for old, drafty houses? Only in part; blower door testing is also recommended on new construction homes. Builders have certain codes and requirements they have to construct homes to, but to ensure things were done correctly to ensure an airtight home, more than a visual inspection is needed. A blower door test can put to rest any doubts a buyer has about their new home. We are often called out by both homebuyers as well as home builders.

AcuSystem Inspections provides Blower Door Testing to all of our primary and secondary locations. If you are purchasing a new construction home or even an older home, consider having a blower door test conducted alongside your home inspection. If you have any questions regarding this service or any of our others, please feel free to contact us!

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