The Best Method for Caulking Windows

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Stop drafts and moisture around your windows with our caulking guide
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Caulking your windows helps seal gaps between the frame and your wall to make your home more energy-efficient. Moisture build-up and drafts can lead to costly bills or repairs, so putting fresh caulk around your windows is a really important but really easy DIY project. The caulk you use depends on where you apply it, but we’ll walk you through it all. Keep reading to learn what type of caulk is best for your repairs and how to get a smooth application.

Things You Should Know

  • Cut or scrape off old caulk and loose paint from around your window. Wipe the window with a damp cloth to remove any dirt and debris on the surface.
  • Run a bead of caulk along the window seam from the corner to the center. Then, run the caulk from the opposite corner until it meets in the middle.
  • Smooth out the caulk with your a caulk tool or a dampened finger. Let the caulk cure for 24 hours.
Part 1
Part 1 of 2:

Choosing the Right Caulk

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  1. Use siliconized latex for waterproofing window exteriors. Siliconized latex caulk contains silane, which makes it more weather-resistant and durable than other latex varieties. have better adhesive properties than acrylics. Siliconized latex products can easily be painted over so you can easily blend it in with your home’s exterior paint. [1]
  2. Choose silicone caulk for indoor and outdoor applications. Silicone is one of the most common and most durable types of caulk available. Silicone caulk is water-resistant and is durable through extreme temperatures, so it’s perfect for sealing your windows inside and out. [2]
    • Silicone caulk is a little tacky and may be more difficult to smooth out than other varieties. IT also does not take paint, so be sure to get a tinted variety if you want a specific color.
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  3. Work with polyurethane caulk for the most durability. Polyurethane isn’t affected by temperature changes and it’s water-resistant, so it holds up for the longest after you apply it. Polyurethane caulk works well indoors and outdoors, but it does break down with UV exposure from the sun, so be sure to paint over any exterior applications. [3]
    • Polyurethane caulk tends to be more expensive than other varieties, so it may not be the most budget-friendly option if you’re caulking a lot of windows in your home.
  4. Acrylic latex doesn’t flex or expand when the temperature changes, so it may not stay bonded to your window frame. It also isn’t as water-resistant, so it’s more prone to moisture damage. Because it can be painted over, acrylic latex is best used for sealing baseboards or securing loose tiles rather than around window frames. [4]
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Part 2
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Applying Caulk to Your Windows

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  1. Wait until a dry day with no rain and low humidity to apply the caulk so it adheres and sets properly on the surface. Make sure the window surface is completely dry before caulking your windows. [5]
    • If you apply caulk during humid or rainy weather, the moisture could cause swelling and make the caulk crack. It may also trap moisture and promote rot.
  2. Remove old caulk from around the window frames with a utility knife. Look for old lines of caulk around the outside of the frame and wherever you see a seam on the window. Slice along the edges of the old caulk lines around the window to loosen the pieces. Peel off the largest pieces of caulk by hand, and then use a putty knife to remove any remaining bits of the material. [6]
    • If you’re having trouble removing the caulk, apply a caulk softener to the seam and let it sit for 10–15 minutes before scraping it off.
    • Removing all of the old caulk ensures that you get the best seal around your windows.
  3. Wet a cloth and wring out any excess water so the window frame doesn’t absorb any moisture. Gently wipe all of the seams where you plan on applying caulk with your cloth to lift up any dirt, debris, and old paint. Let the surface dry completely before you start to get the best adhesion. [7]
    • If your windows have any rot or damage around the frames, then repair the wood or surface before applying caulk.
  4. Load a caulk gun . To put the tube of caulk into a caulk gun , pull the notched rod on the back straight out and hold it in place. Guide the tip of the caulk tube into the hole on the opposite end of the gun. Then, push the metal rod forward as far as you’re able to. Squeeze the handle lightly just enough to move the plunger securely against the end of the tube inside the cylinder. [8]
    • Use a caulk gun with a thumb release trigger on the handle you have to squeeze before you’re able to move the rod.
  5. Measure down about 1 ⁄ 4 inch (0.64 cm) from the tip and slice the plastic off with a utility knife. [9] Then, stick a long, slender nail into the tip’s opening to break the seal so the caulk can dispense properly. [10]
    • If you want a finer line of caulk, cut closer to the tip. If you need a wider line of caulk to fill a larger gap, then make your cut further down.
  6. Press the tip firmly against one corner of the window frame and lightly squeeze the trigger. Hold the caulk gun with both hands to keep it steady. Pull the caulk gun in a straight line along the seam between the frame and the wall and stop halfway along the seam. Release the trigger and slowly lift the tip of the caulk gun away. [11]
    • Stopping the caulk line halfway makes it easier to create a smooth line without having to reposition the caulk gun.
    • Drag the caulk gun against the smooth glass on the window rather than across the textured siding to get a clean, uniform line.
    • Only enough caulk to cover the gap. The more you use, the harder it is to make clean, smooth lines. [12]
    • Avoid putting caulk over any weep holes along the bottom of the window or where there are moveable parts since you could trap moisture.
  7. Place the tip of the caulk gun on the corner opposite of the one you started on. Slowly squeeze the trigger and make another bead of caulk until it meets the original line in the middle. Continue around all the sides of your window to completely seal the gaps. [13]
    • Avoid running a continuous bead of caulk from one side to the other because it may not have a uniform consistency or thickness.
    • If you’re caulking the interior side of your window, then seal around the outside of the frame and any seams along the bottom. When you’re applying caulk to the exterior, only apply it to the sides and bottom of the window. [14]
  8. Use a caulk tool to smooth over the sealant and remove excess caulk. Run the caulk tool down the bead of caulk about 6 inches (15 cm) and wipe off the excess. Then, continue working down the line in 6 in (15 cm) increments so excess caulk doesn’t build up.. [15] Keep smoothing out the caulk until it has an even finish. [16]
    • This process is also called "tooling" the caulk.
    • If you don’t have a caulk tool, wet a clean cloth and wrap it around your finger. Run your finger along the seam to smooth the caulk.
  9. Even though a "skin" will develop within a few hours, caulk still needs more time to completely harden and cure. Leave the caulk alone and avoid touching it until it completely dries. [17]
    • If there’s humid weather, the caulk may take longer to cure.
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Expert Q&A

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  • Question
    How much of the tip do you cut off on a fresh tube of caulk?
    Barry Zakar
    Handyman
    Barry Zakar is a professional handyman and the founder of Little Red Truck Home Services based in the San Francisco Bay Area. With over ten years of experience, Barry specializes in a variety of carpentry projects. He is skilled at constructing decks, railings, fences, gates, and various pieces of furniture. Barry also holds his MBA from John F. Kennedy University.
    Barry Zakar
    Handyman
    Expert Answer
    This is one of the most common mistakes people make. Just clip the smallest portion off that you possibly can. You don't need a giant bead of caulk in most cases and you can always go over a section twice if you want the caulk to be thicker.
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  • Question
    How do you get an even bead?
    Barry Zakar
    Handyman
    Barry Zakar is a professional handyman and the founder of Little Red Truck Home Services based in the San Francisco Bay Area. With over ten years of experience, Barry specializes in a variety of carpentry projects. He is skilled at constructing decks, railings, fences, gates, and various pieces of furniture. Barry also holds his MBA from John F. Kennedy University.
    Barry Zakar
    Handyman
    Expert Answer
    Just try to maintain an even amount of pressure while you're pulling the trigger on the gun. If you squeeze really hard, you have to move the gun quickly, so work slow instead of fast if you want a consistent thickness.
    Thanks! We're glad this was helpful.
    Thank you for your feedback.
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  • Question
    What's the easiest way to smooth the caulk down?
    Barry Zakar
    Handyman
    Barry Zakar is a professional handyman and the founder of Little Red Truck Home Services based in the San Francisco Bay Area. With over ten years of experience, Barry specializes in a variety of carpentry projects. He is skilled at constructing decks, railings, fences, gates, and various pieces of furniture. Barry also holds his MBA from John F. Kennedy University.
    Barry Zakar
    Handyman
    Expert Answer
    Stick your index finger under the sink, get it wet, and use your finger to smooth it down. This will give you a clean, even look.
    Thanks! We're glad this was helpful.
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      Tips

      • Window caulk usually lasts around 5–10 years, so replace it whenever you notice drafts or see visible damage.
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      • If your window frames are rotted or damaged, have gaps larger than 1 ⁄ 4  in (0.64 cm), or are older than 20 years, consider replacing them for ones that are more efficient.
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      References

      1. ↑ https://todayshomeowner.com/windows/guides/caulking-windows-for-winter/
      2. ↑ https://youtu.be/j_I0bhZ6jrc?t=257
      3. ↑ https://youtu.be/YKgstfN6d4U?t=92
      4. ↑ https://www.fcimag.com/articles/96843-how-to-choose-and-use-the-right-caulk-or-sealant
      5. ↑ https://www.energy.gov/energysaver/caulking
      6. ↑ http://state.ces.ncsu.edu/wp-content/uploads/2014/03/DIY-Caulking-Around-Doors-and-Windows.pdf
      7. ↑ https://www.energy.gov/energysaver/caulking
      8. ↑ http://www.bobvila.com/articles/how-to-use-a-caulking-gun/#.VFKvB_nF-So
      9. ↑ Barry Zakar. Handyman. Expert Interview. 16 July 2020.
      1. ↑ https://energync.org/wp-content/uploads/2017/03/Calking_Windows.pdf
      2. ↑ Kevin Turner. Commercial Handyman. Expert Interview. 15 July 2020.
      3. ↑ Kevin Turner. Commercial Handyman. Expert Interview. 15 July 2020.
      4. ↑ Barry Zakar. Handyman. Expert Interview. 16 July 2020.
      5. ↑ https://www.nrel.gov/docs/fy01osti/28039.pdf
      6. ↑ Kevin Turner. Commercial Handyman. Expert Interview. 15 July 2020.
      7. ↑ https://todayshomeowner.com/windows/guides/caulking-windows-for-winter/
      8. ↑ https://www.energy.gov/energysaver/do-it-yourself-savings-project-using-caulk-seal-air-leaks

      About This Article

      Article Summary X

      Before caulking your windows, start by removing the old caulk from the window frame with a putty knife and cleaning off any dirt, debris, and old paint. Afterwards, press the tip of your caulk gun against 1 corner of the window, and squeeze the trigger to apply the caulk in 1 continuous bead until you reach the other corner. Then, repeat the process for the other sides of the window. Finally, remove any excess caulk using a popsicle stick or a rag placed over your finger, and let it dry for at least 24 hours. For more advice, including how to choose the right type of caulk for your windows, keep reading.

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        Sep 28, 2017

        "The right kind of caulk. I have newer windows that were just put in 10 - 11 years ago and the caulk is separating ..." more
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