Air sealing your home increases energy efficiency and decreases energy bills. Finding and fixing the air leakage points is the key to maintaining a more efficient home.

Air sealing your home has multiple benefits including increased energy efficiency and decreased energy bills. It also stabilizes the temperature in your home to improve comfort year-round. Finding and fixing the air leakage points is the key to maintaining a more efficient home.

All homes have air leaks. Luckily, there are consistent areas where air leakage is most likely to occur. These areas include windows, doors, vents, and chimneys. There can also be cracks and holes within your home. While there are several tests that can be done by you or a professional to determine air leakage, a DIY visual inspection of common leaky areas is a great first step to saving money by air sealing your home.

Background

Air sealing is a process that works to eliminate unwanted airflow in a home. This may be felt as a draft. However, extra airflow can happen in attics and ducts, and through doors and windows. This extra airflow is called air leakage. It decreases the efficiency of a home and can increase energy bills. Additionally, air leakage can cause one floor of a home to be significantly warmer or cooler, making it uncomfortable.   Here’s a full breakdown of what air sealing is.

So what are the common leaky areas in a home? We’ve listed them below, with some details on each.

Windows

Windows are one of the biggest causes of air leaks in a home. There are several places on a window that can cause air leakage, including the seal that is created when a window is locked, cracks between the frame and the window, and any other small holes or cracks anywhere within the window, frame, or panes.

A picture of an old single pane window being removed from the house opening, showing a big gap in the house. This window is being removed to replace it with an Energy Star energy efficient window, which will help with air sealing the house.
Our old/original single pane windows were so bad on the net-zero renovation we did, that we had to swap them out. We used double panel hurricane impact Energy Star windows and it helped seal the house right up.

Older windows tend to be leakier than newer windows. General wear and tear on a window over time can cause seals not to be as tight or small cracks to form. If you live in an older home or have older windows, it is very likely that they are causing a decent amount of leakage. At the same time, even with newer windows, it is important to lock them when they are closed to make sure the seal is as tight as possible.

Luckily, sealing windows is one of the easiest and most effective ways of air sealing a home.

There are some permanent fixes for sealing windows, including caulking around the exterior of the window and filling in any visible gaps or holes. This can be done as a fairly low-cost DIY project. Before caulking, it can help to do a visual inspection on the exterior of the windows to determine if there are any cracks or gaps.

While you don’t need to check your windows all that often, every few years it is a good idea to do a quick visual inspection. This will ensure that the caulk is still doing its job and confirm that no additional air leakage points have developed.

Doors

Exterior doors can be a big contributor to air leakage. Because they need to open and close, it can be tough to get a full seal and prevent air from flowing into and out of your home. Doors are sometimes forgotten when discussing leaky areas because they open and obviously allow air in. However, when they are closed they are part of the home’s air sealing equation.

Sometimes you can even feel the air leakage from doors, most commonly at the top or bottom, but from the sides as well. There are several options for reducing the air leakage of doors. If you have a sliding door such as a patio door, make sure that it locks and seals, like a window. If there is noticeable air leakage, you may be able to seal it with caulk.

Picture of half of an old green door closed against a tan wall.
Gaps between the door and the door frame and other areas can be leaking air day and night, making all your mechanical/HVAC sysstems work overtime.

For areas of a sliding door that cannot be caulked, and for any other doors, weatherstripping is a simple fix that is low-cost, easy to install, and highly effective. It comes in different materials and colors and can be attached to the bottom or top of a door. It helps create a better seal without impeding the functionality of the door itself.

Another more temporary fix for air sealing the bottom of doors is to get a cloth or weighted door draft stopper. These are placed along the bottom of a door and are movable. These are not as effective as weather stripping, but they still reduce air leakage.

Attics

Attics (and basements if you have one) can have an impact on air leakage and airflow within a home. If there is insufficient insulation anywhere within the structure, specifically the attic, the airflow of the home can be significantly compromised.

view of an attic space with lots of insulation for added air sealing
Don’t overlook the attic just because you’re under it! The attic of our First Attainable Home has lots of insulation. (even though it’s messy from the previous owner’s DIY)

Insulation is key no matter where you live. Most people think insulation is more important in cold weather climates; however, it is essential in warmer areas as well. Without proper insulation, air can blow through the house from top to bottom and side to side.

It is very hard to DIY insulate a house, so this aspect of air sealing will likely have to be done by a professional. Luckily, having good insulation in your home should have an immediate effect on your energy bill and the overall efficiency of the home.

Chimneys

The chimney is another main culprit for air leakage. If not properly sealed, it is basically an open outlet for the air in the home to escape. Most modern chimneys have an airtight cover that will act as a good air seal to prevent leakage; however, if you have an older chimney, it could be contributing significantly to the efficiency, or lack of efficiency, of your home.

There are several areas of the chimney that can cause air leakage. The obvious one is the top of the chimney. Chimneys should all have some form of cover or seal that is open when the chimney is in use and closed when it is not. These covers, however, do not always have the quality of seal you may desire. Wind, critters, or debris could compromise the seal. There is also human error, when you forget to close the cover after using the fireplace.

Chimney covers can be expensive but are very effective. It’s worth it to hire a professional to install one correctly.

view of a white house with a red brick chimney
Don’t let your energy bills go up in smoke–or air. Photo by Emma Frances Logan on Unsplash

A cheaper option is a chimney balloon. It is critically important to remember to remove the balloon before starting any fires. This can be a great option for people who do not use their fireplace very often, though.

The second key location where you can improve the air sealing of your chimney is the doors between the fireplace and your home. There are a lot of material, design, and color, options for chimney doors. If you realize that your fireplace doors are leaky, you might be able to tighten them up with a screwdriver or other appropriate tool. If not, you might want to replace them altogether.

Cracks or Holes

There is natural wear and tear to the exterior of a house, even if no major events or accidents happen to cause damage. Cracks and holes can form from critters, wind, or just age. Identifying and fixing them can take a bit of time. However, it is not very costly or labor-intensive.  Fixing cracks and holes is an easy DIY option for homeowners.

The first step to fixing cracks or holes is to do a thorough inspection of the exterior of your home. Even the smallest cracks and holes cause air leakage. While having one crack or hole will not change the efficiency of your home much, the more there are, the more the impact of their air leakage adds up. Similarly, the more holes or cracks you identify and fix, the more of a positive impact the air sealing will have on the efficiency and energy savings within your home.

Once the cracks or holes are identified, exterior caulk or filler can be used to fill any holes, gaps, or cracks on the exterior of the house. It is most important to check any locations where there is access from the outside to the inside of the house such as windows, doors, vents, or utility lines. If you have shutters or anything else attached to the exterior of your home, you can look behind those pieces to ensure no critters have made a home there or are using it as an access point to your home.

Caulk and filler are easy to use, do not require a lot of tools, and come in a wide variety of colors. They even have a clear option as well so if there are no colors that match the exterior of your home, you can still use caulk without it being noticeable.

For bigger holes or cracks, typically larger than ¼”, foam filler or expanding foam is a better option than caulk. It expands to fill an area and completely seal it. This is a bit more labor-intensive because the foam may need to be sanded or cut if it expands too far. It also may need to be painted depending on the color.

Even small holes or cracks can cause air leakage into the home so be diligent as you work your way around your home with the caulk. It doesn’t hurt to do a visual air sealing check on the exterior of your home every few years.

A Real Air Gap Example

One our first net-zero home renovation, the master bedroom had a big problem. There was this soffit/shelf type of area high up near the ceiling. When I was first going around the house to look for air gaps, I found that this entire area was open to the attic. The crazy thing is with these gaps in your drywall is that when you add up the actual opening, it can equal the size of a small window being left open. In the hot Florida climates where the attic gets to 130-140+ degrees Fahrenheit, your HVAC systems just have no chance to keep up with the air infiltration.

A picture of an old light sitting on a ledge in the master bedroom soffit, covered in cobwebs and showing a huge air gap into the attic.

So a big part of the air sealing part of the project was to remove these old lights and seal up the drywall completely in this area. The HVAC system was also on the other side of the house, meaning that it’s now having to push cold air about 70ft across the house, into a master bedroom that has this kind of air leakage. This makes for a hotter room (or colder in the winter) with an unbalanced temperature dispersion through the house. Doesn’t feel good!

So we sealed it up –

Our drywall contractor is standing on a 6ft ladder with a neon green shirt, drywalling the air gaps in our master bedroom.
A picture of a soffit or shelf towards the ceiling in our master bedroom. It shows drywall plaster and a sponge, and the shelf being totally air-sealed for energy efficiency.

Conclusion

Unfortunately, air leakage is simply a part of owning a home. It is impossible and even unsafe to try to eliminate all air leakage, but it is important to minimize it as much as you can. Remember, even if you work to seal every area you can, there will still be some natural areas within the home that have some leakage. This is both safe and healthy.

The six common leaky areas of a home include windows, doors, attics, exterior cracks/holes, chimneys, and floors. Each of these has its own fixes and best practices for maintenance and upkeep. There is some overlap for the materials used for fixes such as caulk or weatherstripping. It can be very beneficial to do a full inspection of your home before buying materials to ensure you purchase the correct amount.

Older homes naturally have more leakage than newer ones. By having a well-sealed home, you will save money on energy bills and your house will be more comfortable. You may find that the temperature between floors stabilizes and that you can’t feel the change in weather as significantly as before the air sealing was completed.

Many of the above options can be done by a professional or as a DIY project. Some fixes may be more complex than others depending on your experience and comfort level with materials or tools. A professional may cost more but will likely find more air leakage points. And, if purchasing tools is necessary, the professional may end up being cheaper and more effective in the long run.


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