Window Caulking 101

Window Caulking 101
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3 months ago
Reviewed by Bryan Baeumler

As window installation experts, we know how to best caulk windows. It takes skill, patience, and the right tools, and it provides the perfect seal to your window when done right.

From what it is to do's and don'ts, our team is here to walk you through the process.

What is Window Caulking?

Window caulking is one of the last steps in window installation. Caulk can seal up panes, trim, and sills, and although it can be a messy job, it is necessary. A good caulk job will protect your windows from moisture, extreme temperatures, and even air leaks.

In a climate like Ottawa, caulk is essential for any window installation. We have cold winters and scorching hot summers, so creating an airtight seal that will limit energy transfer and temperature swings is an essential part of the job.

Window Caulking: The Dos and Don'ts

There are a few major do's and don'ts of the trade when it comes to caulking.


  • Choose the appropriate caulking for your windows. Ensure that it is an exterior window caulk when doing exterior windows, or, make sure that you are using a proper indoor caulk when you intend to caulk or use silicone around interior windows.
  • Pick a caulk gun with a thumb release. Yes, it will cost a little more, but the savings on caulk and clean-up will pay for themselves.
  • Use both hands when operating the gun. Control the bead and the gun and use two hands.
  • Smooth out small sections of the bead. Generally, professionals will smooth out six to eight inches at a time before cleaning and re-wetting their finger or tool.


  • Do not caulk over old caulk - remove it, clean the surface, and dry before breaking out the caulk gun. This will ensure that you have a clean bead that will seal.
  • Overcut the end of the caulk. You only need to cut enough for a point larger than a bead, and you will not have control over your line.
  • Caulk a continuous bead from top to bottom or along a single side. You want to caulk from one end to the middle, stop, and then start from the other end and meet in the middle. This will result in a uniform bead across the entire surface.
  • Use caulking as a filler for poorly trimmed windows. If you are trying to caulk a hole larger than a ¼ inch, you need to use a foam backer rod and then caulk it. Caulk is not a filler.

How to Caulk Your Windows

When it comes to how to caulk a basement window or any window in general, the prep is the first and possibly one of the most critical steps.

  1. Prep the area
    When you are getting ready to caulk, you want to caulk on a dry and clean surface. If you are caulking a window, you will want to remove any old caulking with a razor blade or putty knife. Once removed, you will want to remove all the paint, dirt, debris, grease, and even water. You want to thoroughly clean during this step, as it will help you in the long run. Next, you will wish to rub down the area with rubbing alcohol or disinfecting spray and wipe it down with water and a rag.
  2. Tape the area
    Tape is a great way to ensure you have clean lines and less of a mess to clean up; whether you are a seasoned hand or a newbie, tape is your friend. Generally, it is good to use painter's tape for this job.
  3. Cut the caulk
    This might seem like a simple job, but it will mean a world of difference in the overall job. You will want to trim enough off the nozzle so a large bead comes out. Some caulks include a guide, and you should always cut at a 45-degree angle.
  4. Apply the caulk
    Next, you will load the caulk in the caulk gun and adjust the rod to expand fully. Then, you will place the nozzle at a 45-degree angle and start caulking. Be slow, steady, and always hold the gun with two hands. Release the trigger when it reaches the handle, and continue doing it as far as you need. The goal is to have a single bead of caulk that is even throughout.
  5. Smooth the caulk
    With either a tool or your finger, you will want to run over the bead to smooth out the caulk. If you are using your finger, you will need a glass of water to dip your finger in periodically. Aim to have even pressure throughout and a smooth finish. Once you have smoothed out the caulk, remove the tape and let it dry.

We understand caulking may appear to be a simple process, but a professional will always have that extra touch to ensure everything is done right. It might be time to call the experts at Canadian Choice Windows and Doors to ensure you get the perfect finish every time.

Cost to install windows


What type of caulk do you use for windows?

It will depend on what you are doing. If you are looking to complete caulking around windows with vinyl siding, you will need an exterior caulk that will be waterproof. If you are looking to caulk inside, an interior caulk will do the trick.

Should you caulk the inside of a window?

Yes, you will want to caulk both the interior and exterior of the window. Caulk allows for a seal to develop that will not allow air or heat to escape through your window, so a proper caulk will go a long way. However, we should note that you will need to use an interior caulk on the inside of a window.

What is the best caulking to use to seal a window?

There are many great options when it comes to caulking. If you are unsure what the best caulking is, give our team a call, and we can certainly help out - or, if you prefer, head down to your local hardware store and ask one of the experts. We suggest using silicone caulk to better stand up to our climate than a latex-based caulk.

Julia Gurevich
Julia Gurevich

Julia Gurevich is a versatile content writer with a passion for delivering captivating narratives through a diverse and attentive approach. Her eye for detail helps her craft content that resonates with audiences across varied home improvement industries, capturing the perfect balance between information and entertainment. As a content coordinator, Julia takes pride in delivering content that leaves a lasting impact through her ability to navigate seamless content strategies and collaborative projects between teams. In her free time, she enjoys exploring Toronto’s cultural landscape, visiting local parks, and getting to know members of the community through events and activities.

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Reviewed by Bryan Baeumler

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