Door Draft Stoppers and Window Insulation Kits: What They Save and Which to Buy
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They are among the cheapest winter fixes. The Department of Energy says caulking and weatherstripping often pay for themselves in a year or less. For doors, a stick-on door sweep such as the Holikme or Vellure seals the gap at the bottom, and weatherstripping seals the frame. For old single-pane windows, a shrink film kit (the 3M Indoor Window Insulator or Duck MAX) adds an air space that brings the window close to a clear double-pane one. By PNNL’s window figures, that saves about $12 a window each winter with gas heat in Ohio and about $38 with electric heat, before counting the drafts it also stops. The picker below works it out for your state and heating.
- Shrink film kit
- 5 windows
- Shrink film kit
- 10 windows
Most guides to draft stoppers and window kits stop at “they help.” This one puts a number on the window side with the Pacific Northwest National Laboratory’s window measurements and NOAA’s heating degree days for your state, and sorts the door and window fixes by what each actually does, from the Department of Energy’s air-sealing advice and the Efficient Window Coverings program.
Where the cold gets in
Air leaks in through gaps where parts of the house meet and through the parts that move. The Department of Energy’s air-sealing advice uses caulk for gaps between parts that don’t move, such as around door and window frames, and weatherstripping for parts that do, such as doors and windows that open. Its checklist also includes:
- replacing exterior door bottoms and thresholds with ones that have pliable sealing gaskets;
- sealing where pipes, ducts and wiring pass through walls, floors and ceilings;
- foam gaskets behind outlet and switch plates on outside walls;
- keeping the fireplace damper closed when it is not in use.
Windows lose heat two ways: through the glass, and through leaks around the sash and frame. PNNL’s Building America guidance gives a typical old single-pane wood window a U-factor of 0.84 and air leakage of 1 to 4 cubic feet a minute per square foot, against 0.1 to 0.3 for a new double-pane window.
Door draft stoppers and weatherstripping
- Stick-on door sweeps are silicone strips that stick to the bottom of the door and close the gap to the floor. The Holikme fills gaps up to 1 inch, by its listing. They suit interior and exterior doors and take minutes to fit; clean and dry the door first; on a cold day Holikme suggests warming its sweep with a hair dryer before fitting.
- Weatherstripping around the frame seals the sides and top of a door, or the sash of a window that opens. Self-stick foam or rubber tape suits most frames. Many exterior doors have a groove (a kerf) in the frame for a press-in seal; when the old one is flattened or torn, replace it with a kerf seal that fits the groove.
- Fabric draft snakes that lie against the bottom of an interior door block drafts too, but must be moved every time the door opens.
A simple check: on a windy day, hold a strip of tissue near the edges of the closed door. Where it flutters, air is getting through.
Window insulation kits: how they work
A window insulation kit is a sheet of clear plastic film that you tape to the inside of the window frame and shrink tight with a hair dryer. It does two things: it stops drafts leaking around the sash, and it traps a still layer of air between the film and the glass, which slows the heat escaping. The Efficient Window Coverings program says interior window panels, which work on the same principle, bring a window close to the performance of a clear double-pane window when properly installed.
PNNL’s figures show how big that step is:
| Window | U-factor | Heating and cooling savings vs single-pane |
|---|---|---|
| Single-pane wood window | 0.84 | — |
| With a clear storm panel | 0.50 | 5 to 20% |
| With a low-e storm panel | 0.36 | 12 to 33% |
| Clear double-pane window, no coating | 0.50 | — |
| Clear double-pane with a low-e storm panel | 0.27 | — |
We count a well-fitted film kit like a clear storm panel. That is the basis of the picker above; the film is thinner than a rigid panel and only lasts a season, so treat the figure as an estimate. Kits matter most on single-pane windows; for clear double-pane windows, PNNL’s figures only cover adding a low-e panel.
Fitting tips: apply the tape to a clean, dry frame, then shrink the film tight with a hair dryer, as Duck’s listing describes. Kits are made for one season; Frost King’s listing advises re-applying every year and taking the film off if you want to open the window in warm weather.
Every window fix compared
| Fix | What it does | What the evidence says |
|---|---|---|
| Weatherstripping and caulk | Stops drafts around the sash and frame | DOE: quick returns, often one year or less |
| Shrink film kit | Stops drafts and adds an insulating air layer, for one season | Close to a clear double-pane window, like an interior panel (Efficient Window Coverings) |
| Thermal curtains and drapes | A fabric layer that traps air when closed | The tighter they fit to the sill or floor, the more heat loss they stop; in summer, window coverings cut solar heat gain by 20 to 60% (Efficient Window Coverings) |
| Cellular shades | Honeycomb fabric with air pockets | Insulated cellular shades add about R-1 to R-2 to a window, or about R-4 with side tracks (Efficient Window Coverings) |
| Low-e storm or interior panels | A rigid extra layer with a heat-reflecting coating, left up year-round | Single-pane U-factor 0.84 to 0.36; 12 to 33% heating and cooling savings (PNNL) |
| Replacement windows | New ENERGY STAR windows | See what they save in your climate with our window replacement calculator |
Curtains and shades only help while they are closed, so close them at night and on cloudy days and open them to let winter sun in. For heat lost through the roof rather than the windows, see the attic insulation calculator.
The same cold spots can freeze pipes. Our guide to heat tape for pipes covers the Red Cross’s frozen-pipe steps, CPSC’s heat tape safety rules and which insulation to use.
Before you seal: ventilation and escape routes
- Ventilation: the Department of Energy advises checking your ventilation needs before air sealing. Homes need some fresh air, and gas or oil furnaces, water heaters and fireplaces need air to burn safely. If you seal a lot of gaps, have an energy assessor check the house, and make sure you have working carbon monoxide alarms.
- Escape routes: fixed interior panels can block a window you would need to climb out of, as the Efficient Window Coverings program notes. Leave bedroom windows you would use to escape a fire openable, or use a kit you can tear away quickly.
- Fireplaces: seal around chimneys and flues only with fire-resistant materials, as DOE advises, never with foam or plastic.
Our picks
Sizes and features below are from each product’s own Amazon listing, checked on 7 October 2026.
| Best for | Pick | Key spec | Amazon |
|---|---|---|---|
| Window kit, 5 windows | 3M Indoor Window Insulator Kit, 5 windows | Shrink film kit | Check price |
| Thicker film, 10 windows | Duck MAX Strength Window Insulation Kit, 10 windows | Shrink film kit | Check price |
| Most windows | Frost King indoor shrink window kit, 9-pack | Shrink film kit | Check price |
| Patio doors and large windows | Frost King shrink window kit, 84 x 110 in | Shrink film kit | Check price |
| Door sweep | Holikme door draft stopper, 41 in | Door sweep | Check price |
| Door sweep | Vellure door draft stopper | Door sweep | Check price |
| Two doors | Grotheory door draft stopper, 2-pack | Door sweep | Check price |
| Door and window frames | Frost King D-section rubber weatherseal | Weatherstripping | Check price |
| Replacing an exterior door seal | Litaibai kerf weather stripping, 40 ft | Kerf seal | Check price |
- Shrink film kit
- 5 windows
- Shrink film kit
- Up to 10 windows
- Shrink film kit
- 9 windows
- Shrink film kit
- 1 large opening
- Door sweep
- 41 in
- Door sweep
- 39 in
- Door sweep
- 2 x 39 in
- Weatherstripping
- 17 ft
- Kerf seal
- 40 ft
How these were chosen
We picked widely sold kits and seals from established brands whose Amazon listings state their size and what they fit, and that were in stock on 7 October 2026. The window savings in the picker multiply the drop in U-factor from PNNL’s Building America guidance on low-e storm windows (single-pane wood 0.84, with a clear storm panel 0.50, with a low-e panel 0.36) by the window area, your state’s 1991 to 2020 heating degree days from NOAA and 24 hours, then price the heat at your state’s residential fuel or electricity price from the EIA. A gas, propane or oil furnace is taken as 80% efficient, our assumption for an older furnace; a heat pump uses the average rated efficiency of ducted heat pumps installed through Mass Save in 2024. Counting a film kit like a clear storm panel is our assumption, based on the Efficient Window Coverings program’s description of interior panels. Air-sealing advice: Department of Energy, Energy Saver.
Sources
- Pacific Northwest National Laboratory for DOE Building America, Low-E Storm Windows brochure (PDF)
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991 to 2020
- Efficient Window Coverings (DOE-supported program)
- U.S. Department of Energy, Energy Saver: Air Sealing Your Home (archived copy)
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A: average residential electricity price by state
- U.S. Energy Information Administration, natural gas prices: average residential price by state
- U.S. Energy Information Administration, residential heating oil and propane prices
How we pick products for every buying guide: our buying guide standards.
Frequently asked questions
Yes, especially on single-pane windows. The film stops drafts around the sash and traps an insulating layer of air. Interior panels that work the same way bring a window close to a clear double-pane one, according to the Efficient Window Coverings program; PNNL gives that step as a U-factor of 0.84 down to 0.50.
On a 3 x 5 ft single-pane window in Ohio, about $12 a winter with gas heat and about $38 with electric heat, from PNNL’s window U-factors, NOAA heating degree days and EIA prices. Colder states and pricier fuels save more, and stopping drafts adds to it. The picker on this page works it out for your state.
Yes, if they close the gap. The Department of Energy recommends weatherstripping doors and replacing worn door bottoms and thresholds with ones that have pliable seals, and says caulking and weatherstripping often pay for themselves in a year or less. A stick-on sweep suits most doors; replace a worn kerf seal around an exterior door frame too.
It depends on the frame. If the frame has a groove (a kerf), a press-in kerf seal that matches the groove width is the most durable. Without one, self-stick rubber or foam tape works; pick a thickness that closes the gap without stopping the door from latching. Seal the bottom of the door with a sweep.
They help when closed and fitted closely. The Efficient Window Coverings program says the tighter curtains fit to the sill or floor, the more they reduce heat loss, by trapping a layer of still air. In summer, closed window coverings cut solar heat gain by 20 to 60%.