Seal Gaps with Caulk

Caulking fills stationary gaps and cracks around window and door frames where they meet the wall, siding, or trim. Unlike weather stripping, which seals moving parts, caulk is applied to joints that do not move. A single tube of caulk costs $3-8 and can seal several windows. Silicone caulk is more flexible and weather-resistant than latex, making it the better choice for exterior applications where temperature swings cause materials to expand and contract. Latex or acrylic latex caulk is easier to apply and paintable, making it preferable for interior use.

How to Caulk

1. Remove old, cracked, or peeling caulk with a putty knife or caulk removal tool.
2. Clean the surfaces with rubbing alcohol and allow them to dry completely.
3. Cut the caulk tube nozzle at a 45-degree angle to create an opening slightly smaller than the gap you are filling.
4. Apply steady pressure on the caulk gun while moving at a consistent pace along the gap. Fill the joint completely without leaving voids.
5. Smooth the bead immediately with a wet finger, a caulk finishing tool, or a damp cloth for a clean appearance.
6. Allow the caulk to cure according to the manufacturer's directions before painting or exposing to moisture.

Where to Caulk

• Where window or door frames meet exterior siding
• Where interior trim meets the wall around windows and doors
• Around exterior dryer vents, pipe penetrations, and conduit near windows
• Along the joint between a window sill and the frame

Tips

• Apply caulk when temperatures are above 45F for proper adhesion and curing
• Silicone caulk cannot be painted; use paintable silicone-latex hybrid if you need both flexibility and paintability
• Backer rod (foam rope) should be pressed into gaps wider than 1/4 inch before caulking to reduce the amount of caulk needed and improve the seal
• Inspect caulk annually and reapply where it has cracked or pulled away