What you need to know before caulking your home exterior

July 28, 2015

Taking care of the exterior of your home is essential to protecting it. When repairs to your home exterior require caulking as part of the job, here's what you'll need to know:

What you need to know before caulking your home exterior

Caulk siding joints

  • Watertight caulk joints are key to keeping your wood siding and exterior trim in good shape for generations.
  • Each spring, check the caulk joints on the outside of your house.
  • If the caulk is brittle or cracked, dig it out and replace it. You'll cut down on drafts and save on your energy bills, too.

When to keep your caulk gun in its holster

  • Exterior caulk helps stop drafts and seals the end-grain of clapboards where they meet windows, doors, and corner boards.
  • But it's not necessary to seal the bottoms of boards where they lap the board beneath.
  • In fact, this actually could create a problem by trapping interior moisture in the boards, causing paint to peel.

Shapely caulk joints last longest

  • Your caulk joints will last longest if you give them an hourglass shape.
  • In other words, you want the caulk to be thick where it adheres to both sides of the joint but thinner in the middle.
  • The thicker sides adhere well, while the thinner middle lets the caulk stretch more easily, reducing the chance that the caulk will separate from the sides of the joint.
  • Flexible joints are most important when caulking outdoor wood, such as where siding meets window and door casing.
  • That's because outdoor wood expands and contracts a lot, and good caulk seals are important to long-lasting house exteriors.
  • So rather than just filling up these joints with caulk, fill most of the space with foam backer rod. Run your bead of caulk; then smooth the joint with a wet finger to create the outer concave shape.

Use the right caulking compound for the job

  • Different compounds will suit different needs, depending on where and how you're using it. Some are better for indoor jobs, and others for outdoor jobs.
  • Price may play a factor in your decision making, but make sure to weigh your options with the long term in mind.
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