Conquer the Leaks: Blower Door Basics

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Is your house feeling drafty?

In many homes, unwanted wind makes its way through cracks and holes in the building. Luckily, this leaking air can by stopped by a process called air sealing.

You may think that air sealing simply involves patching up the leaks under doors and near windows, but there are many techniques that professionals use to locate exactly where sealing will benefit your home the most.

The best method to pinpoint where to seal is the blower door test. The blower door can predict how much energy you will save from air sealing by finding exactly where you need to seal. By creating a big pressure difference between the inside and outside of your home, the blower door accurately finds all of the areas where your home leaks air.

Using a blower door is not a complicated or time consuming process. Professionals fit a temporary frame and a flexible panel in a doorway leading outside. A fan is used to change the pressure between both sides of the door, which then creates faster airflow. This faster flow makes it easy to find where your home leaks the most.

The blower door technique saves you time and money because it quickly finds the most important leaks to seal, so you do not waste anything on sealing any minor leaks.

Another important outcome of using a blower door is finding a Minimum Ventilation Guideline (MVG). The MVG of a home allows us to effectively air seal without over-tightening buildings that do not have a ventilation system. By finding the major problem areas and sealing them off, a home without a ventilation system will have enough airflow for ventilation balanced with air sealing. By sealing off the main leaks, you will save money and energy.

The blower door technique can be compared to drinking out of a broken straw. An unbroken straw does not require as much effort to drink out of; your drink easily flows up the straw and into your mouth. On the other hand, a straw with holes up the side needs a bigger pulling force put into it in order to maintain a steady pressure and bring the drink to your mouth.

Like your mouth on the straw, a blower door pulls air out of your home in order to depressurize the building. Depressurizing acts as a vacuum to pull air through the cracks, so we can find where air is escaping the fastest, like the biggest holes in a broken straw.

The total surface area of the holes along with the pressure difference between the inside and the outside of the home determine how much air volume the blower door blows to effectively depolarize your home. The blower door needs to pull air out of your home at a faster rate than any of the internal leaks. This makes every leak visible and helps us evaluate which leaks will benefit most from being sealed.

A blower door evaluation is a simple process that can help you save. Whether you want to conserve energy to help the environment, help your wallet, or both; the blower door is the best way to start air sealing and saving energy in your home.