How to Put Plastic on Windows Outside: 12 Steps

Shrink-film window insulation is one of the cheapest ways to cut winter drafts, reduce condensation, and lower heating bills. This guide covers the full outside application: measuring, cleaning, cutting, and heat-shrinking the film so it stays tight all season. You’ll need a few basic supplies and about 30 minutes per window.

What You’ll Need

• Exterior-grade shrink film kit (includes double-sided tape and film)
• Hair dryer or heat gun on low setting
• Utility knife or sharp scissors
• Spray bottle with water and a drop of dish soap (for cleaning)
• Clean, lint-free cloth or paper towels
• Measuring tape
• Step ladder (if windows are above ground level)
• Putty knife or flat scraper (to press tape into corners)

Step-by-Step

1. Measure each window frame. Use a tape measure to get the width and height of the glass area plus the frame. Add 5 cm (2 inches) to each dimension so the film overlaps the frame by about 2.5 cm (1 inch) on all sides. Write down the numbers for each window.
2. Clean the window frame thoroughly. Dirt, dust, and old adhesive prevent the tape from sticking. Spray the frame with soapy water, wipe off grime, then dry completely with a lint-free cloth. Pay extra attention to the top and bottom edges where tape will go.
3. Choose a dry, mild day. Apply the film when the temperature is above 10°C (50°F) and there’s no rain in the forecast. Cold makes the tape brittle and the film less pliable.
4. Apply the double-sided tape around the frame. Peel the backing off one side and press the tape onto the frame, about 1 cm (0.5 in) from the outer edge. Run it continuously around the entire frame, pressing firmly. For long runs, press every 30 cm (12 in) first, then go back and press the middle sections.
5. Cut the film to size. Using your measurements, cut a piece of film from the roll. It’s better to cut slightly larger than too small—you can trim later.
6. Peel the backing off the tape. Do this right before you’re ready to apply the film, so the tape doesn’t pick up dust.
7. Attach the film to the top edge first. Start at one corner, press the film onto the tape, then work across the top. Keep the film slightly taut—don’t stretch it yet, just hold it in place.
8. Press the film onto the sides and bottom. Work from the top down, pressing the film onto the tape with your fingers. Pull the film gently outward as you go to remove wrinkles, but don’t pull hard enough to tear it. Use a putty knife to press the film into corners and along the tape edge.
9. Trim excess film. Use a sharp utility knife to cut off the film that extends beyond the tape. Cut about 1 cm (0.5 in) from the tape edge, so the film doesn’t peel up. Be careful not to cut the tape itself.
10. Heat the film to shrink it. Turn on a hair dryer on high heat (or a heat gun on low) and hold it about 10–15 cm (4–6 in) from the film. Move it in a slow, circular motion, starting from the center and working outward. The film will tighten as it warms. Watch for wrinkles—they should disappear as the film contracts.
11. Reheat any remaining wrinkles. If a wrinkle persists, apply heat directly to it for a few seconds, then smooth it with your hand while still warm. Be careful not to overheat—the film can melt or tear if you hold the dryer too close for too long.
12. Let the film cool and inspect. Once the film is tight and clear, let it cool for a few minutes. Check all edges for any loose spots or gaps. Press them down again if needed.

Common Mistakes

• Applying film in cold weather. Below 10°C (50°F), the tape won’t stick well and the film becomes stiff, making it prone to tearing.
• Not cleaning the frame. Even a thin layer of dust or grease will cause the tape to fail within days.
• Cutting the film too small. If it doesn’t overlap the frame by at least 2 cm (0.75 in), it won’t seal properly and will pull loose.
• Stretching the film before heating. If you pull the film tight while applying, it will shrink too much when heated and may tear or pull the tape off.
• Using too much heat. Holding the dryer too close or in one spot for too long can melt the film, leaving holes or a distorted look.
• Ignoring the bottom edge. The bottom is where drafts enter most, so make sure the tape is pressed firmly all the way across.

Tips

• Use a helper for large windows. One person holds the film while the other presses it onto the tape—this prevents sagging and wrinkles.
• Work from the center out when heating. This pushes air bubbles to the edges instead of trapping them in the middle.
• For very drafty windows, use two layers. Apply one layer, heat-shrink it, then apply a second layer over it for extra insulation.
• Keep the film off the glass. The air gap between the film and glass is what provides insulation. If the film touches the glass, it won’t work as well.
• Store leftover film. Keep the roll in a cool, dry place. It can be used next year for repairs or other windows.
• Remove the film in spring. Leaving it up year-round can cause the tape to bond permanently to the frame, making removal difficult.

Troubleshooting

The film won’t stick to the frame. This usually means the frame is dirty or damp. Wipe the frame with rubbing alcohol, let it dry completely, and reapply the tape. If the tape still doesn’t stick, try a stronger exterior-grade tape.

The film tears while applying. Stop, cut out the torn section, and apply a patch of film over it with a small piece of double-sided tape. Or, remove the film and start over with a fresh piece—it’s easier than patching.

Wrinkles won’t disappear after heating. Heat the wrinkled area for a few seconds, then gently smooth it with your hand while still warm. If it’s still wrinkled, the film may be too loose—reheat the entire window and pull the edges tighter.

The film sags after a few days. This can happen if the tape wasn’t pressed firmly or if the film wasn’t shrunk enough. Reheat the film with a hair dryer—it should tighten again. If it still sags, the tape may have failed; remove the film and reapply.

Condensation forms between the film and glass. This is normal and actually means the film is working—it’s trapping moisture that would otherwise condense on the glass. If it’s excessive, check that the film is sealed tightly at all edges.

The film is cloudy or hazy. This is usually caused by moisture trapped under the film. Make sure the frame is completely dry before applying. If it’s already cloudy, you may need to remove and reapply on a dry day.

Frequently Asked Questions

Can I use regular plastic wrap instead of shrink film?

No. Regular plastic wrap won’t shrink with heat and isn’t durable enough for outdoor conditions. Use a kit labeled for exterior window insulation—it’s UV-resistant and designed to shrink.

How long does exterior window film last?

Typically one season (about 4–6 months). Some high-quality films can last longer, but it’s best to remove it in spring to avoid adhesive residue.

Will the film damage my window frame?

If applied correctly and removed within a year, it shouldn’t. Double-sided tape can leave a sticky residue, but it’s easily removed with rubbing alcohol or a mild adhesive remover.

Can I apply the film over existing paint that’s peeling?

No. The tape needs a smooth, stable surface. If paint is peeling, scrape off loose paint and clean the area first. Otherwise, the tape will pull the paint off when removed.

Does exterior film work on all window types?

It works best on flat frames with a smooth surface—wood, vinyl, aluminum, and painted metal. It’s not suitable for windows with curved frames or those that open outward, as the film may interfere with operation.

Can I open the window after applying the film?

No. The film seals the window shut for the season. If you need to open the window, you’ll have to remove the film first.

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