The Blower Door Test

All buildings leak air through cracks or openings in the structure.

This is called infiltration.

Some houses leak too much and some don't leak enough.

Either way, you can have a problem.

Those that leak too much (high infiltration rate) can bring in unwanted air such as humidity or dry air (depending on the climate), dust, mold and carbon monoxide)

Houses that don't leak enough (Low infiltration rate) can cause other problems.

Some of the problems can be unhealthy, elevated carbon dioxide levels, excess humidity that can lead to other issues, like mold and dust mites .

Low infiltration rates can also cause combustion appliances to produce dangerous carbon monoxide levels and/or inadequate venting of the combustion by-products, causing them to enter your living area.

How do you know if you have a problem?

The only way to know is to test!

The blower door test can measure the infiltration rate and uncover other problems (for example air duct leakage)

A skilled professional will measure the volume of your home, ask how many occupants live in the house and count the bedrooms because infiltration rates are based on the volume of the house as well as occupancy.

They will then calculate the target infiltration rate and perform the blower door test.

The blower door is a large fan that is placed in the doorway of the building.

The blower door is accompanied by guages that measure the amount of air produced by the fan, enabling the tester to determine the infiltration rate.

With the fan running, most leaks can be located.

Please note, I said most leaks!

Some leaks are hidden within the framing and cavities of the house.

These leaks are often found using pressure diagnostics (measuring pressure difference between the various parts of the house).

Once the infiltration rate is determined, the person who performed the test can prescribe the proper measures.

If the house is too leaky, the recommendation would most likely be air sealing and/or insulation.

Too tight would mean you would have to install some means of mechanical ventilation to bring in the right amount of fresh air.

In either case, the test will have to be repeated to ensure the measures do not cause unsafe conditions.

Click here to find a blower door test contractor in your state.