How to Seal Air Leaks Around Windows and Doors

Seal air leaks by applying weatherstripping to moving parts and caulk to stationary gaps, focusing on areas where you feel drafts or see daylight between frames.

1. Find Every Hidden Draft. Close all windows and doors, then walk around your home holding a lit candle or incense stick near the frames. Watch for flickering flames or smoke movement that indicates air flow. You can also feel for drafts with your hand or look for visible gaps where daylight shows through. Mark problem areas with painter's tape so you don't miss any spots during repairs.
2. Strip and Scrub Clean. Remove old caulk, dirt, and debris from all areas you'll be sealing. Use a putty knife or caulk removal tool to scrape away old material, then wipe down surfaces with a damp cloth. Let everything dry completely before proceeding. Clean surfaces ensure better adhesion for new weatherstripping and caulk.
3. Match Materials to Gaps. For doors, use door sweeps for the bottom gap and adhesive foam or V-strip weatherstripping for the sides and top. For windows, foam tape works well for casement windows, while V-strip is ideal for double-hung windows. Measure your gaps first - small gaps under 1/4 inch need thin foam tape, while larger gaps require thicker materials or door sweeps.
4. Seal Doors Bottom-Up. Start with the door sweep at the bottom. Measure the door width, cut the sweep to size, and attach it so it just touches the threshold when the door is closed. For the sides and top, apply adhesive-backed weatherstripping to the door stop where the door closes against it. Press firmly and ensure the door can still close properly without binding.
5. Wrap Windows Tight. Apply weatherstripping to the window sash where it meets the frame. For double-hung windows, install V-strip in the side channels and along the bottom of the upper sash. Press the weatherstripping firmly into place and test the window operation. The window should close snugly but still move smoothly.
6. Apply Caulk with Precision. Use exterior-grade caulk for outside gaps and paintable acrylic caulk for interior work. Cut the caulk tube tip at a 45-degree angle to create a bead slightly smaller than your gap. Apply steady pressure while moving the gun smoothly along the gap. Immediately smooth the bead with your finger or a caulk tool for a clean finish.
7. Confirm Seals Hold Fast. After installation, test all doors and windows to ensure they operate smoothly. Check your work by repeating the candle test or using a dollar bill - if you can pull a bill through a closed door or window easily, you need more weatherstripping. Make adjustments by adding material or repositioning existing strips.