How to Caulk Windows

By Gene and Katie Hamilton

Tools Required
  • Hammer
  • Nailset
  • Chisel
  • paint brush
  • Caulk gun
  • Utility knife
Materials Required
  • Caulk

Before You Begin

Check the condition of the siding and framing to see if it needs to be repaired or replaced. If necessary, do the work before applying new caulk. Tighten loose nails with a hammer and nailset.

Prepare surface for caulk

Inspect the caulk around the frame and if it has become brittle or pulled away from the joint, use a chisel to remove it. Clean out the joint carefully and use an old paintbrush to dust out the joint so it's perfectly empty.

It takes a steady hand and concentration so practice first. Before starting your project, run a trial bead on some scrap material to get accustomed to the sealant application rate.

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  • Step 1 : Load the caulk gun with cartridge

    Load the caulk gun with cartridge

    Cut off the tip of the caulk tube at an angle and load it into the gun. To operate the gun compress the handle so it is comfortable working with the mechanism released, then apply the caulk with a shorter handle movement.

  • Step 2 : Apply the caulk

    Apply caulk

    Seal the joints between trim pieces of a window by holding the gun steady as you carefully release the caulk in the joint.

  • Step 3 : Apply caulk to siding

    Apply caulk to siding

    Carefully direct the caulk into the joint between the siding and window or door framing to seal the space and prevent leaks.

  • Step 4 : Seal the window framing

    Use caulk to seal the gap around the outside of a window frame where it meets the siding. Apply gentle pressure, don't force it.

  • Step 5 : Seal deep gaps with foam

    Seal with foam

    If there is a gap wider or deeper than 1/2-inch, use a foam insulation first to fill the gap, then cut away the excess after it has hardened. Finish the joint with caulk.

  • Step 6 : Caulk inside

    Caulk interior of windows and wallboard

    To fill gaps inside the house where wallboard meets doors and windows, run a bead of caulk down the joint and then immediately wet your finger (slightly) and smooth the bead to give it a neat finish.