How To Detect and Seal Air Leaks at Home

Is hiring a qualified professional to do the job for you really necessary? Within this article you will find instructions on how you can detect air leaks in your house, seal them, and by doing so significantly lower your consumption of energy.


Why Sealing Air Leaks is Important

Statistics show that somewhere between 10% and 30% of energy costs are due to air leaks that could’ve been sealed.  Detecting and sealing air leaks by simple energy conservation techniques such as weatherstripping and caulking will save you money in the long run. Other air leaks might require more complex techniques, but sealing them is most likely well worth it as well! Costs of air sealing are usually paid back within a few years.

In addition to this, weatherstripping and caulking will also at least partially protect your home from noise, insects, pests, dusts and moisture.

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Professional Energy Audits

If you don’t properly seal of those leaks, you will be waste energy and drive up your costs. This is why many people hire professional technicians when it comes to detecting and sealing air leaks.

Professional energy audits usually include a blower door test, an excellent method to detect leaks. Complete assessments will also be able to determine if you should upgrade insulation.

A professional energy audit is a wise thing to do, however, if you are somewhat of a technical guy yourself, you should be able to save some money by doing the job yourself.


How to Test for Air Leaks

Depressurizing your home

The first thing you have to do is to depressurize your home. When this is done, you can perform tests to identify air leaks. Don’t worry, this sounds a lot more complicated than what it actually is. There are three simple steps involved:

  1. Close all windows and doors. This is a critical step, so make sure you don ‘t miss anything!
  2. Next up is turning off any furnace or air-conditioner you have.
  3. Lastly, turn on exhaust fans and dryer. Alternatively, use a large fan in a window that you keep open to move air out of the building.

I should also mention that assessing air leaks on your own is best done on a windy day in cold weather.


Look for air leaks with one of the following methods:

Now the fun part starts. You can detect air leaks by using either one of the following methods:

  1. The incense stick method is usually the most effective way. Light an incense stick and keep it close to any areas where you suspect an air leak (look at the typical places for air leaks below). The smoke will be sucked in at the places where there is in fact leakage.
  2. With the next method is only for door sand windows. You need a sheet of paper. Open and close all windows and doors with this paper in-between. If you are able to slide it in or out without the paper ripping, chances are you have a leak.
  3. The last method we will cover does not require the depressurizing of your house that is mentioned above. It is best done in dark. All you need is a flashlight and a volunteer. What you do is walk around your house and shining your flashlight on places that are likely to have air leaks. Make sure that this is well coordinated with the person on the inside who detects the leakage by seeing the light.


Where are the biggest air leaks typically found?

Typical air leaks

Source: United States Environmental Protection Agency

Below is a list over common places where you can find air leaks. In addition to the places on this list, go around both on the inside and outside of your house and add any susceptible places to the list:

  • Around windows and doors (moldings)
  • Anywhere wood and brick meet
  • Holes used for wiring
  • Recessed lights
  • Behind kneewalls (the short walls that you can find in your attic)
  • Attic access door or hatch
  • Where plumbing and chimney penetrates ceilings, floors and walls
  • Where the basement foundation meets the wood framing (sill plates and rims)
  • Where gas piping enters your house

Typical air leaks chart

The general recommendation is to start sealing air leaks in the basement and the attic. These are often the places where the biggest holes can be found and by properly sealing them will yield big benefits straight away.

As you can see, there are many things you can do to find and seal air leaks in your own house. However, a professional energy audit is often a good place to start and will ensure that know your priorities on where energy efficiency needs to be improved in your own house. Read more about this in What is a Home Energy Audit? and Energy Audit – Blower Door, Thermographic or PFT Testing?

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