Snowfall, “endless” snowball fights and trees covered with a white snowy blanket make up for a perfect winter season. However, this time of the year sees a rise in heating/air conditioning costs and not even a cup of hot cocoa can alleviate you from the cold temperatures. So it is important to eliminate drafts and air leaks form your windows. 

Weatherizing your home especially at one of its biggest weak links–the windows–is a cost-effective measure to counter the dreaded effects of the cold weather. To put it simply, your end goal is to minimize air leaks into and out of your home by sealing all possible air entry points.

Finding Window Air Leaks

Visual test

Drafts can come from the edges, damaged weather strips, gaps or cracks on your windows. Normal wearing out with time may cause the double-hung sashes in wood windows to shrink or the gaskets in aluminum or vinyl windows to wear out. Therefore, carrying out a thorough visual inspection is more than ideal in zeroing in on the problematic areas.

Smoke test

Alternatively, you can try the commonly practiced smoke test during a cool and windy day. The test involves the following:

  • Begin by turning off all cook stoves and appliances or anything that can affect air flow or pose a safety concern.
  • Then, close all points of entry such as doors, windows, furnaces and so on.
  • Cautiously, light a stick of incense and move it towards any potential point of air leakage in the window.

If there’s a draft (air leak), it will either blow the smoke stream inward or suck it out of the room. Also, don’t forget to check obvious air leakage points on the exterior side of the storm windows and frames.

Caulking and weather-stripping are the most effective means to seal off air leaks. Specifically, caulking is used for the stationary parts of the window while weatherstripping is for the movable parts. After which, extra insulation may be installed for optimal energy efficiency.

Sealing Air Leaks Using Weatherstripping

Weatherstripping for windows range from V-channel, felt to foam tape types. Although the choice of either will mostly depend on your preferences, do make sure to go for a variant that is long-lasting and can withstand friction, temperature variations, weather and so on.

For instance, rubber stripping may not be ideal if you live in areas that have high-temperature summers as the material will melt at such heat and may even seal the windows shut. So, to install a new weatherstripping you will require the following; non-expanding self-adhesive foam, weatherstripping, measuring tape, utility knife or scissors, soap and water, finishing nails and a hammer.

Instructions to Follow:

  1. Begin with cleaning the surfaces, bottom of sash and jamb, with soap and water and leave to dry before starting on the next step.
  2. Measure the window sides and cut the stripping and foam to the length while leaving some extra allowance on the former. Next, peel and stick the self-adhesive foam against the bottom of the sash.
  3. Then, peel and install the V-channel strip in between the jamb and sash stiles and secure it in place by hammering the finishing nails through it and into the jamb. So far, installing felt and foam weatherstripping will also follow the same steps and be just as easy.
  4. The last step is to test the closing/opening mechanism of the sashes to ensure they don’t catch the nails.

Repairing loose weather stripping is also an option, but it will depend on the intensity of damage. Start with a clean surface, applying the non-expanding foam and lastly using adhesive to hold the stripping back in place.

Applying Caulking to Prevent Air Leakage

Caulking come in water-based or solvent-based variants. It may come in malleable rope options or in squeezable containers for easy usage.

Usually, the best time of the year to apply caulk is during dry or warm weathers as it will set in more evenly. Before applying caulk always ensure that the surface is clean, dry and free from old paint or old caulk. Furthermore, always apply it on all the cracks and window frame joints. Also include the connection between the frame and wall.

Other minor upgrades like adding a solar control film, panels, coverings and even rejuvenating storm windows will go a long way in minimizing the effects of any air leaks you may have missed.


Heat gain and/or loss through windows accounts for about 25% to 30% of most home’s heating and cooling energy usage. Keeping that in mind, you can track the overall effectiveness of your weatherizing measures by carry out regular home energy assessments. Finally, if all the above measures don’t improve on your home’s energy efficiency then you may want to consider replacing your windows.

Video – How-To Caulk Your Window