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Should You Air Seal Baseboards

With all windows and doors shut tight and no fireplace in sight, the presence of a draft in a room is baffling at the very least. To many people, it’s downright infuriating. If you’re anything like me, then you have probably sleuthed around until finally pinpointing that tiny gap between your baseboards and the floor as the source of the dreaded draft.

Those gaps don’t look big enough to cause trouble, but, unfortunately, they don’t need to be any bigger to cause trouble. These gaps are compromising the air seal of your house, and a cold draft is not the only concern here; those little cracks are costly when it comes to energy usage in the home.

Air sealing baseboards is an important step in air sealing a house and preventing air leakages from interfering with the HVAC system. Baseboard gaps allow unconditioned air into a house and allow conditioned air out. This is costly for both energy and utility bills.

Drafts Pulled From Baseboard Gap

Baseboard gaps are a prime location for pulling cold air into a room, as well as letting conditioned air escape. Unfortunately, walls often curve, which can create significant space for cold air to enter the house.

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Conditioned spaces are supposed to have controlled airflow in order to manage heat loss/gain and the chimney effect.

The chimney effect, or stack effect, describes how hot air rises and sits near the ceiling. The displaced air creates a vacuum-like effect near the floor in this system, and a well-sealed house or room will cause the internal air to circulate fully.

stack chimney effect

However, this is not what happens when there is a gap in the baseboards. The gaps in your baseboards are affected by the vacuum, and the result is this: air will be pulled through the openings and prevent the recirculation of air.

If there is air being pulled into the space, this will impact how the room retains heat as it interrupts how the HVAC system is able to manage the temperature and airflow in the room or house.

Draft Affects HVAC and Utility Bills

These drafts interfere with your HVAC system by adding extraneous variables. Air enters your house and allows or forces the conditioned air to leave. In winter, baseboard gaps will allow cold air into your home, which is what creates drafts as well as cold spots.

In summer, the cool air you are trying to keep in is going to get vacuumed out through those same gaps that let winter air in, as the chimney effect is created on the other side of the wall.

These fluctuations affect the functioning of your HVAC system. It will have to work harder and longer to try and combat the air leaking in and out. The result? Your energy efficiency is sorely lacking, and you are paying for it, quite literally. This can reach extremes, to the point where some people might even be overpaying utilities by 30% because of air leaks.

So, drafty baseboards are an energy drain. The good news is you can save an extra 15% on utility bills if you patch up the gaps allowing air leakage and if you have good insulation. However, first check if the gap indicates a deeper-lying structural or poor design issue.

How to Air Seal a Baseboard

To air seal your baseboards, you will need to get yourself some caulk and possibly some foam sealant, such as Sashco Big Stretch Acrylic Latex Caulking Sealant (amazon link) and Great Stuff Foam Sealant (amazon link).

Air Sealing with Caulk

  • Run fresh caulking along the top and bottom of the baseboard.
    • If you have carpeting, pull back the carpet, expose the bottom of the baseboard and subfloor and apply the caulk. Wait until the caulk is dry before replacing the carpet.
    • When it comes to wood or tile floors, you will need to run painter’s tape, like ScotchBlue Painter’s Tape 1.41” x 45 yards (amazon link), along the floor side of the seam and get it to sit as flat and close to the gap as possible. This will prevent caulk from messing on your floor.
  • Next, apply the caulk with the nozzle flat on the baseboard; you need to apply enough that the tape won’t pull up the seal and leave gaps when removed.

Air Sealing with Foam Sealant

If there is a large gap creating a strong draft, you are going to need something a little more than caulking. This is where foam sealants come in handy; they are used to fill in more sizable gaps.

  • Start by removing the baseboard.
  • Spray foam sealant into the hole.
  • Replace the baseboard.
  • Caulk the baseboard, top and bottom, as previously described.

For more details on these methods as well as a third alternative option, you can read Seal Baseboards to Stop Draft: 3 Easy Ways.

Improve Effects of Air Sealing Baseboards

To maximize your efforts in sealing your baseboards to prevent air leakages, you can also take additional action.

While the large gaps can be a good place to start air sealing your baseboards, you should not stop there. Smaller cracks are still problematic and need sealing.

Additionally, ensure that the sealing is done along the entire length and width of the room; otherwise, you will only be partially dealing with the problem.

Look Beyond the Baseboards

Sealing your house is not limited to leaky baseboards.

You will need to seal up your walls and ceiling (especially around where wires or pipes run through) as well as any gaps or cracks around windows and doors.

The gaps and cracks on and around the walls, ceiling, windows, and doors of a room allow air to enter and leave. The ones near your ceiling enhance the loss of conditioned air and entrance of cold air from the baseboards by strengthening the chimney effect.

So, these gaps also interfere with your HVAC system, decrease energy efficiency, and increase your utility bills.

House repairing, skirting board; baseboards

Gaps around window frames can be sealed up with caulk and foam, or you may need to replace the weather-stripping. Caulking, foam sealing, and weather-stripping can also solve problems with a drafty external door.

The only additional advice I would like to offer is to ensure that proper sealing has not been overlooked (or become compromised) around your vents and in your attic and basement, as this can create a stack effect that affects the whole house.


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