How to Replace Window Caulk

Old, cracked window caulk lets in water, air, and insects. Replacing it is one of the highest-return home maintenance tasks you can do — it takes about an hour per window and can prevent thousands of dollars in water damage. Here's how to do it right.

Why Does Window Caulk Fail?

• Age — most caulk lasts 5–10 years before cracking
• UV exposure degrades the caulk material
• Thermal expansion and contraction cycles cause cracking
• Moisture infiltration behind the caulk causes it to separate
• Wrong caulk type used originally (latex caulk on exterior joints fails quickly)

What You'll Need

• Silicone caulk (exterior grade)
• Caulk gun
• Caulk removal tool
• Utility knife
• Rubbing alcohol and cloth
• Painter's tape

• GE Advanced Silicone Caulk Window & Door Clear — 100% waterproof, freeze and sun proof, 5x stronger adhesion; the right product for exterior window caulking
• Bates Caulking Gun 10:1 No Drip — 10:1 thrust ratio for smooth, controlled bead; no-drip mechanism prevents mess
• Caulking Tool 5-in-1 Silicone Removal Kit — grout scraper, silicone pads, and adhesive scraper; removes old caulk cleanly without damaging the frame

Step 1: Remove All Old Caulk

This is the most important step. New caulk applied over old caulk won't bond properly and will fail quickly. Use a caulk removal tool or utility knife to cut and scrape out all old caulk from the joint. Work carefully to avoid scratching the window frame or siding.

Step 2: Clean the Joint

Wipe the joint with rubbing alcohol to remove all dust, oil, and adhesive residue. Let dry completely — at least 30 minutes. Silicone caulk won't adhere to a damp or dirty surface.

Step 3: Apply Painter's Tape

Apply painter's tape on both sides of the joint, leaving the gap exposed. This gives you clean, straight caulk lines and protects the frame and siding from smears.

Step 4: Cut the Caulk Tube Nozzle

Cut the nozzle at a 45-degree angle. Start with a small opening — about 3/16". You can always cut more off, but you can't put it back. A smaller opening gives you more control.

Step 5: Apply the Caulk

Hold the gun at a 45-degree angle to the joint. Apply steady, even pressure on the trigger while moving at a consistent speed. Fill the joint completely in one continuous pass — don't stop and start, as this creates weak spots.

Step 6: Smooth the Bead

Immediately after applying, smooth the bead with a wet finger or caulk finishing tool. Press firmly to push the caulk into the joint and create a concave surface that sheds water.

Step 7: Remove the Tape

Pull the painter's tape off while the caulk is still wet, pulling at a 45-degree angle away from the joint. If you wait until the caulk is dry, the tape will tear the caulk edge.

Step 8: Let Cure

Silicone caulk is typically tack-free in 30–60 minutes and fully cured in 24 hours. Avoid rain or water contact during curing.

How Often to Recaulk Windows?

Inspect exterior window caulk every year. Recaulk when you see cracks, gaps, or areas where the caulk has pulled away from the frame. Most exterior windows need recaulking every 5–7 years.