How to Detect and Seal a Window Air Leak


Have you ever been surprised by your energy bill at the end of the month? Sometimes, colder or hotter weather can lead to spikes in our bills. Other times, your home may have areas where it’s losing efficiency, leading to higher energy costs. One possible culprit is window air leaks, where windows or doorways are not properly sealed against the outside. Not only can this have a negative effect on your home’s energy efficiency, it can also present an area for liquid and moisture to enter your home, leading to the possibility of mold, wood rot, and other adverse effects. Today, let’s look at how you can detect and seal a window air leak.

Inspect Windows 

The easiest way to identify a window air leak is to check for light and drafts. To check for light, darken the room during the daytime, and see if any additional light is coming in where you wouldn’t expect it to. Next, head outside and inspect the state of your windows from this perspective. Take note of any obvious crack, damaged wood, or gaps in the seal. Next, head back inside, and feel around each window. If there is a gap in your window, you should be able to feel the air entry.  If you can’t detect leaks simply by feel or looking proceed to the next step.

The Candle Test

First, ensure all airflow in the area you’re testing is off. Air conditioning, heat, fans, etc. Next, light a candle. Take the lit candle, and move it around the frame of each window in question. When a leak is present, the smoke from the candle will drift towards the gap. This simple test can help you identify leaks you otherwise may not have, and can help you address issues before they become more serious. 

Check the Locks

Windows that aren’t able to properly lock may be a sign that the window has an issue with sealing. Sometimes, locks can be inhibited by paint. Other times, your window may have swollen in the window frame, making it difficult for the window to properly seal. Other times, damage to the frame can cause the window to not be able to properly latch.

Inspect Doors

Next, take a look at your doors. Doors typically present more obvious signs of inefficiency and can usually be identified by visually. First, look for any noticeable cracks or other damage that may allow for air to enter. Next, inspect the weather stripping that seals the gaps all around the door. If it is flimsy, or coming off, it may be time to replace the weather stripping altogether. 

Identifying Other Problem Areas

The US Department of Energy identifies other areas that present the opportunity for air leaks into your home. They include:

  • Electrical outlets
  • Switch plates
  • Door and window frames
  • Electrical and gas service entrances
  • Baseboards
  • Weather stripping around doors
  • Fireplace dampers
  • Attic hatches
  • Wall- or window-mounted air conditioners.
  • Cable TV and phone lines
  • Where dryer vents pass through walls
  • Vents and fans.

Identifying problem areas throughout your house will allow you to more successfully diagnose and deal with air leak problems. 

The Risks of Air Leaks

Air leaks are typically felt in your energy bill, as they put a dent in your home’s inefficiency by lessening its ability to keep hot or cold air in. However, there are other problems they can pose. Exposure to moist air can damage the wooden window frame, compounding leak problems and leading it to need a replacement. Similarly, if a leak is large enough, water can find an entry point to your home, which can lead to additional rotting, as well as the formation of mold and mildew. Mold and mildew are harmful to the health of those living in your home, so you should take every possible step to prevent their formation. 


Air leaks can be resolved rather simply, or require more complicated solutions with professional help. Caulk can help temporarily resolve many leaks that your window frames are experiencing. Replacing window framing altogether may be the best option to secure your windows from air intrusion. However, if you’re unsure how best to proceed, it may be wise to enlist professional help. As a Maryland exterior remodeling company, Four Twelve Roofing has worked with numerous clients to address areas of moisture entry to their homes. We can tell you whether you’re in need of a simple patch job, or a full window replacement Baltimore base on the scale of the problem. With over 300+ reviews on Google averaging 4.8 stars, we’re proud to have earned the trust of our clients by providing professional, friendly service delivered by honest estimators and contractors. If you want to protect your home and energy bill, reach out to the team at Four Twelve today.

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