How to find and seal drafts around windows and doors
A sheet of paper finds the leaks. Caulk the frames, weatherstrip what moves, and put plastic over the window you cannot fix this year.
Why sealing comes first
ENERGY STAR says sealing air leaks and adding insulation can save up to 10 percent on your annual energy bills, and names the simple fixes: weatherstripping on doors and caulking around windows. It is also the cheapest work on this site.
Find the leaks first
Two tests from ENERGY STAR's project pages, both free:
- The paper test. Close a window or door on a sheet of paper. If it slides back and forth easily, that joint could be tighter, usually with thicker weatherstripping.
- The smoke test. Hold a lit incense stick next to the seams and the sash. If the smoke is pushed one way, air is moving there.
Other signs: rattling windows, gaps you can see around the trim, dust or pests getting in, and peeling paint around a frame.
Caulk or weatherstrip
- Caulk fills gaps between parts that never move: around window and door frames, where trim meets the wall.
- Weatherstripping seals parts that open: window sashes, door edges. A sweep seals the bottom of a door.
The caulk and weatherstrip counter works out how many feet of each, and how many tubes.
The window you cannot fix this year
Shrink-to-fit plastic over the window. ENERGY STAR calls it easy, effective and inexpensive: tape around the frame, film on the tape, a hair dryer to pull it tight.
Behind the trim
Air that leaks around the window frame, behind the trim, is a bigger job. ENERGY STAR rates sealing behind trim a moderate to difficult project, best done when you are replacing a window anyway.
The steps for windows and doors
- Find the drafts with a sheet of paperClose a window or door on a sheet of paper. If it slides out easily, that joint needs thicker weatherstripping. A lit incense stick held at the seams shows moving air too.
- Caulk the trim, weatherstrip what movesCaulk fills gaps around window and door frames, which never move. Weatherstripping seals the parts that open: sashes and doors. The counter works out how much of each.
- Put plastic film over the drafty windowsShrink-to-fit plastic over a window is easy and inexpensive, and it stops a draft you cannot fix this year.
Sources
- ENERGY STAR: Seal and insulate with ENERGY STAR energystar.gov
- ENERGY STAR: Sealing behind window and door trim project energystar.gov
- ENERGY STAR: Applying plastic over windows project energystar.gov
Drafted on October 26, 2026 with a language model from the pages listed above, each opened that day, and sampled by the editor after publication. Every figure is computed by the same code the tools run, and a test fails the build if one stops matching.
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