Best Window Insulation Kits: Shrink Film for Drafty Windows (2026)

A window insulation kit is a temporary storm window you put up from inside. Double-sided tape goes around the window trim, clear plastic film goes on the tape, and a hair dryer shrinks the film tight. ENERGY STAR says the film reduces drafts, helps the house feel warmer in winter, and reduces moisture buildup from condensation on the window, and that when it extends over the woodwork it also stops the air leaks around the window. The trade-off: the window stays shut until you take the film down in spring.

This guide covers what the kits can and can't do, rolled film versus pre-cut sheets, which windows to leave alone, how to put the film up so it seals, and how to take it down. Then come four picks from Duck and Frost King, chosen from the makers' specifications and instructions. Film is one fix for a drafty window: our weatherstripping guide covers the seals for windows you still open, and one room colder than the rest covers the other reasons a room stays cold.

At a Glance

What a Window Kit Can and Can't Do

Film works like a storm window. Montana State University Extension calls trapped air one of the best insulators, and a storm window traps a layer of it against the glass. Taped to the trim, the film also covers the leaks around the window. The Department of Energy's Energy Savers booklet suggests exactly this for cold weather: tape clear plastic film to the inside of your window frames to reduce drafts. ENERGY STAR calls the kits easy, effective, and inexpensive.

Montana State rates plastic film about as effective as the other add-on storm windows, removable glass or rigid plastic panels and permanent combination storms, though it says the pricier types are more attractive, more convenient, and let you open the window for fresh air. Keep the scale in mind, too. ENERGY STAR says window projects may have less impact on energy use than attic and basement work, though windows are easier to reach and suit a do-it-yourself job. No official source we checked puts a number on what film saves, so we don't either.

Film won't fix a failing window. Frost King says fogging between the panes, rotting frames, or serious condensation may mean it's time for professional repair or replacement.

Rolled Film or Pre-Cut Sheets?

Rolled kits: nothing to measure

Duck's rolled kits come as one long roll of film plus tape. You tape the top of the window, roll the film across from right to left, and cut it off, then tape the sides and bottom and unfold the film onto them. Because you cut the film once it's on, Duck says there's no measuring. One roll covers several windows: up to five from the 62 x 210-inch roll, up to ten from the 62 x 420-inch roll.

Pre-cut kits: one sheet per window

Frost King's standard kits come as boxed sheets, each 42 x 62 inches, for standard windows, with larger sheets for extra-large windows and patio doors. Measure across the outside edges of the trim, where the tape goes, before you buy. ENERGY STAR says to buy a kit that fits the width of your window and to leave a few inches of film on either side, and Frost King's instructions call for at least an inch of overhang all around.

Standard or heavy-duty film

Frost King lists its standard film at 0.75 mil. Both makers sell a heavier grade: Duck says its Max Strength film is puncture-resistant and two times thicker than standard window kits, and Frost King's heavy-duty kits use 1.5-mil film it calls twice as strong as standard, with extra-wide tape. University of Maryland Extension notes that thicker films are easier to handle and more durable, and Duck pitches its heavier film for high-traffic and pet-friendly homes.

An indoor kit, on a surface the maker allows

Buy an indoor kit for inside the house. Duck says its outdoor kit tape stays soft indoors and may peel off paint and varnish or leave a very sticky residue. Then check your trim against the makers' lists. Frost King's instructions say to install only on metal, painted wood, or vinyl, and never on wallpaper, wallboard, plaster, or veneer. Duck lists painted or finished wood, aluminum, and vinyl, and says its kits aren't safe for plaster, drywall, wallboard, or unfinished wood. If the only place for the tape is drywall or plaster, as on a window with no trim, neither maker's kit is meant for it.

Which Windows to Leave Alone

• Escape windows. A filmed window can't be opened until the film comes down. NFPA's escape planning calls for two ways out of every room where possible and says to make sure doors and windows can be opened easily, and the U.S. Fire Administration says to make sure doors and windows aren't blocked. Don't film a bedroom window someone may need to climb out of.
• Doors you'd escape through. A patio-door kit seals the door shut for the winter, too. NFPA warns that items blocking doors and windows could keep you from escaping a fire, so film a door only if nobody would need to get out through it.
• Window air conditioners. The kits are made for windows. Frigidaire's winter advice is to take a window unit out, following the installation instructions for your model, and store it. If one has to stay in, Duck and Frost King each sell an indoor cover made to fit around it, and NFPA says a room with a window air conditioner still needs a second way out.

How to Put Up a Window Kit

1. Check that the trim is at least 40°F. Duck says its tape needs a surface that warm to stick. On a colder one, Duck says to warm it with a hair dryer first, press the tape on firmly before removing the liner, and then warm the tape to soften the adhesive.
2. Clean the trim. Frost King says the surface must be clean, dry, and grease-free. ENERGY STAR lists cotton balls and rubbing alcohol among the tools, and Duck suggests a general-purpose or alcohol-based cleaner.
3. Unhook any mini-blind wands. Film over a window can keep you from working the blinds. ENERGY STAR's fix: lift the wand off its hook before you film; afterward, put four overlapping strips of cellophane tape on the film around the hook, cut out the center with a new utility blade (a dull blade will rip the film), and rehang the wand.
4. Tape all the way around the trim. Frost King says to press the tape firmly around the window frame and along the bottom sill. Keep it on the trim so the film covers the whole window: ENERGY STAR says film stops leaks around the window when it extends over the woodwork.
5. Put the film on. For a pre-cut sheet, Frost King says to apply it slightly taut, first across the top, then the bottom and both sides, leaving at least an inch of overhang. For a roll, Duck says to tape the top, roll the film across from right to left, cut it, tape the sides and bottom, and unfold the film onto the tape. Put the roll's loose edge on the top tape, not the folded edge.
6. Shrink it with a hair dryer. Frost King says to use the highest setting, hold the dryer 4 to 6 inches from the film, and never touch the plastic with the hot dryer. Duck warns not to over-shrink: the extra pull on the tape can make it come away from the window. Trim the excess film when you're done.
7. Check the seal. Duck's last step is making sure the film fits tightly all the way around. A gap lets humid room air reach the cold glass behind the film, where it can condense.

Condensation Behind the Film

Film normally cuts condensation, because the room side of the window gets a warmer surface. The Building America Solution Center, a Department of Energy program, says that's what an interior storm does, but only if it's as airtight as possible: if humid room air gets past it, moisture can condense on the glass behind. It adds that this is most common in fall and spring, when it's cool outside but the air still holds plenty of moisture.

If you see moisture behind the film, the Solution Center's first fix is a better seal. If condensation keeps coming back, it suggests cutting indoor humidity: run bath fans when showering or cooking (timers or humidity sensors help), dry clothes outdoors or in a dryer vented outside, and run a dehumidifier if needed. Our window condensation guide covers indoor humidity in detail.

Taking It Down in Spring

ENERGY STAR says to take the plastic down when winter is over. Duck and Frost King both say to warm the tape with a hair dryer first to soften the adhesive, then pull off the film. Frost King says the adhesive should come off with the film, and that stubborn bits loosen with more heat and then warm soapy water or a household cleaner; Duck recommends its adhesive remover for residue. If the film is still in good shape, Frost King says you can store it for next winter, away from direct sunlight and heat.

Picks Worth Buying

1. Best overall — tougher film on a roll

This is the kit our weatherstripping guide picks for windows that can stay shut until spring. Duck says the Max Strength film is puncture-resistant and two times thicker than standard window kits, and pitches it for high-traffic and pet-friendly homes. Because it's a roll, there's nothing to measure: tape, roll, cut, and shrink. One roll covers up to five windows, and the only tools are scissors and a hair dryer. Duck lists painted or finished wood, aluminum, and vinyl as suitable surfaces, says the kit isn't safe for plaster, drywall, wallboard, or unfinished wood, and calls its removal clean enough for renters.

2. Best for a whole house — ten windows from one roll

When most of the house is drafty, one roll can cover it. Duck's standard rolled kit goes up the same way as the Max version: a roll of crystal-clear film plus tape, no measuring, and the film cut to size once it's applied. It has the same surface list and the same clean-removal claim. The difference is the film: Duck says its Max film is two times thicker than standard kits like this one, so choose Max for windows that pets or a busy hallway might test.

3. Best pre-cut kit — one sheet per standard window

If you'd rather work with one sheet per window, Frost King's boxed kits make it simple. Each 42 x 62-inch sheet is meant for a standard window, so measure the trim first and allow at least an inch of overhang all around. Frost King's instructions are short: install only on metal, painted wood, or vinyl, never on wallpaper, wallboard, plaster, or veneer; apply the film slightly taut, top first; and shrink it with a hair dryer on its highest setting, held 4 to 6 inches away. The same sheet comes in 1-sheet (V73H) and 9-sheet (V73/9H) boxes, and Frost King makes a 1.5-mil heavy-duty version (V83M).

4. Best for big windows — one large sheet

A standard sheet won't cover a wide window or a glass door. Frost King's V76H is a single 84 x 110-inch sheet of 0.75-mil film for patio doors or large windows, and it goes up the same way as the standard kit. Before you film a door, remember that it stays shut until spring: use it only on a door nobody would need to escape through. For tougher film at this size, Frost King makes a heavy-duty 84 x 120-inch, 1.5-mil version (V86M).

How We Chose

We compare the category first — what a first-time homeowner actually needs from a window insulation kit — then weigh manufacturer specifications, verified buyer feedback, and how the product type is used in real homes. We don't accept free products or payment for placement, and every pick names its compromise. 3M also makes indoor window insulator kits; they're not picked here because we couldn't confirm their current specifications from 3M. How we research and review.

Frequently Asked Questions

Do window insulation kits really work?

For drafts, yes. ENERGY STAR says the film reduces drafts and condensation, helps the house feel warmer in winter, adds a layer of insulating air, and stops leaks around the window when it extends over the trim. It also says window projects may have less impact on energy use than attic and basement work, and no official source we checked puts a number on what film saves.

Can I open the window with the film on?

No. The film is taped around the whole window, so it stays shut until you take the film down. Leave a bedroom's escape window unfilmed: NFPA says every room should have two ways out where possible, and doors and windows should open easily.

Can I use a heat gun instead of a hair dryer?

Use a hair dryer: it's what Duck, Frost King, and ENERGY STAR all call for. Frost King says to use the highest setting, hold the dryer 4 to 6 inches from the film, and never touch the plastic with it, and Duck warns that over-shrinking the film can pull the tape away from the window.

Will the tape peel paint off my trim?

Use it only on surfaces the maker lists. Frost King says metal, painted wood, or vinyl, never wallpaper, wallboard, plaster, or veneer; Duck says painted or finished wood, aluminum, or vinyl, not plaster, drywall, wallboard, or unfinished wood. Buy an indoor kit, since Duck says its outdoor kit tape may peel off paint and varnish indoors, and warm the tape with a hair dryer before you pull it off.

Can I reuse window film next winter?

If it's still in good shape, Frost King says you can store it for next winter, away from direct sunlight and heat.

Why is there condensation behind my window film?

Humid room air is probably getting past it. The Building America Solution Center says an interior storm has to be as airtight as possible, or moisture can condense on the cold glass behind it. Reseal any gaps first, then cut indoor humidity; our window condensation guide explains how.

The Bottom Line

For most drafty windows, the Duck Max Strength roll is the one to buy: tougher film, nothing to measure, and enough for five windows. Get Duck's 10-window roll to do the whole house, Frost King's V73/3H if you'd rather have one pre-cut sheet per window, and the V76H for a big window. Tape it to clean trim the maker allows, at 40°F or warmer, shrink it with a hair dryer, and leave every escape window and exit door free.

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