Information and solutions for a safe, healthy,
comfortable, durable and energy efficient home

Air Leakage and Air Sealing

All homes experience some uncontrolled air leaks through the building envelope (walls, ceilings, windows and doors). However, in excess, air leaks cause high energy bills as well as problems with comfort, indoor air quality and structural durability. In Minnesota’s cold climate there also may be frost in the attic and ice dams.


What is the Problem?

Air leaks occurs when conditioned air leaves the house through cracks and holes in the building envelope and is replaced by unconditioned outside air. The driving force is a pressure differential between inside and outside caused by temperature, wind, stack-effect or mechanical systems. Air going out always must equal air coming in, so the greater the pressure difference the more airflow. The house is over-ventilated on days that are extra windy, hot or cold, and under-ventilated when the weather is mild. Of course a healthy home needs ventilation – just not through costly, uncontrolled air leaks!

Solving the Problem

Your best option is to air seal the home and install some sort of mechanical ventilation. The first step is to determine if uncontrolled air leakage in your home is actually an issue. A Certified Energy Professional can conduct a blower door test to measure the total air leakage. He will also use an infrared camera and/or smoke to find invisible leaks around windows, doors, lights in the ceiling, plumbing and electrical penetrations in the attic, chimneys and attic hatches. Finally, he’ll determine if mechanical ventilation is needed after air sealing is done.

Next steps

  1. Learn more about energy audits and hiring certified energy professionals
  2. Find a certified energy professional
  3. Hire the appropriate professional(s) as recommended in the scope of workl
  4. Build your confidence by reviewing additional resources:

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