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Outdoor · Free DIY Guide

How to Caulk Exterior Window Trim

  • Time: 1–2 hours
  • Difficulty: Easy
  • Steps: 5

Cracked caulk around windows lets in water and air. Re-caulk in dry weather, ideally between 40°F and 80°F.

Tools & materials

  • Exterior polyurethane or siliconized sealant
  • Caulk gun
  • Putty knife or 5-in-1 tool
  • Stiff brush
  • Backer rod for wide gaps
  • Ladder

Step by step

  1. Step 1

    Scrape out loose and cracked caulk. Brush away dust and debris.

  2. Step 2

    Make sure the surface is completely dry.

  3. Step 3

    Push backer rod into gaps wider than 1/4 inch.

  4. Step 4

    Run a continuous bead along the joint between the trim and siding, and where trim meets the window.

  5. Step 5

    Tool the bead smooth with a wet finger or tool, and leave the bottom weep holes on windows open.

When to stop and call ProFix

If you see any of these, stop and call us:

  • The trim is soft or rotted
  • Water stains appear inside around the window
  • Windows are on a second story or higher

Not in the mood to DIY? A ProFix pro can handle it for you in Chicago Metro and Dallas–Fort Worth, with a written price before work starts.

Related guides

These guides are general information for simple repairs. You're responsible for your own safety and for following local codes and your lease or HOA rules. When in doubt, stop and call a licensed professional. All DIY guides

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