One of the biggest utility costs for any homeowner is energy. Homeowners rely on power for everything from cooking to working to entertainment. Within energy usage, heating and cooling are undoubtedly one of the biggest contributors to the overall cost.

The last thing homeowners need is for the air they’re paying to heat or cool to fly right out of the house. Unfortunately, this is exactly what happens when a home isn’t sealed properly. A blower door test can help homeowners understand more about their home’s seal quality and energy efficiency.

What Is a Blower Door Test?

A blower door test is a test performed by an energy professional to test a home’s seal and determine how airtight it is.

A blower door is temporarily fitted to the frame of the front or back door. This device contains a powerful fan that sucks the air out of the house. The readings from this exercise determine how much air is leaking out.

Steps in Blower Door Testing

A blower door test can sound extreme to a homeowner who isn’t familiar with the process, but it’s actually a relatively simple and fast procedure when done by a qualified professional.


First, the contractor will arrive and perform a quick visual inspection of the home to determine the best place to install the blower door and scope out various inspection points. They’ll then install the blower door to an existing door frame.

Preparing the Home

All exterior doors and windows must be closed. Interior doors are opened to ensure that all rooms in the home are covered during the test. Any other openings to outdoor air, such as flues in wood-burning fireplaces and stoves, are also closed.

As a safety precaution, the contractor will also extinguish pilot lights from stoves and water heaters. Once the house is prepared, the next step is the pre-calculations. This is when the contractor calculates the total volume of airspace in the house, providing a baseline for comparison after the test.

Running the Test

Next, the contractor runs the fan for about 15 minutes. During this time, digital gauges monitor air pressure levels inside and outside the home.

At the same time, the contractor will walk through the house and hunt for drafts. They’ll check manually but may also use a fog generator to detect weaker drafts. Between the preparation, fan running, and cleanup, the entire process should take 45 minutes to an hour.

Blower Door Test Results

Once the test is complete, you’ll receive a report that lets you know how airtight your home is. You’ll know exactly where the drafts are and where air is leaking in or out of your home.

In addition to detecting drafts, you’ll get an overall ACH (Air Changes per Hour) reading, which tells you how many times the air in your home would be replaced in an hour if the door fan continued to run.

If you have a low number (anywhere around four), it means your home is pretty airtight. Readings between six and nine mean you have a moderately leaky house, and reading over nine means you have multiple leaks.

Schedule Your Blower Door Test

Blower door testing is one of the best ways to test your home’s energy efficiency and ensure that you’re not wasting energy and money. It can quickly tell you exactly where you need to make structural improvements to your home.

Depending on the results of your test, you can get in touch with builders, insulation contractors, or window specialists to tighten up your home’s seal and improve its overall function.