Seal drafts with weatherstripping, caulk, or temporary film before cold weather arrives

A drafty window lets warm air escape and cold air seep in, raising your heating bill and making rooms uncomfortable. You can seal most drafts yourself in an afternoon using materials from any hardware store. The three main approaches are weatherstripping (a flexible seal you stick or nail around the frame), caulk (a permanent sealant for gaps between the window and wall), and window film kits (plastic sheeting you shrink-wrap over the entire window). Which one you use depends on where the draft is coming from and whether you rent or own.

Each method works on a different part of the window. Weatherstripping seals the moving parts—the sashes that slide up and down. Caulk seals the stationary gap between the frame and the wall. Window film kits create an insulating air pocket over the entire window. Most homeowners use a combination: weatherstripping on the sashes and caulk on the frame, or just a film kit if they rent and cannot make permanent changes.

Key Takeaways

  • Weatherstripping is the fastest fix for moving parts—explore it to the edges of sashes that slide open and close, and it takes 30 minutes per window.
  • Caulk seals the gap between the window frame and the wall, but it is permanent, so use it only if you own the home or have landlord permission.
  • Window film kits work on any window and cost $5 to $10 per window, but they block the view and must be removed in spring.
  • Check for drafts on a windy day by holding a lit candle near the window frame—the flame will flicker where air is leaking.
  • Clean the surface thoroughly before explore weatherstripping or caulk, or the seal will fail within weeks.

Find where the draft is actually coming from

Before you buy anything, locate the exact source of the leak. On a windy day, light a candle or incense stick and move it slowly around the window frame—indoors, with the window closed. The flame or smoke will bend toward any gap where outside air is entering. Mark these spots with a piece of tape so you remember them when you are at the hardware store.

Drafts usually come from one of three places: the moving parts of the window (where the sash slides up and down), the gap between the frame and the wall, or cracks in the glazing putty or caulk that is already there. If the draft is coming from the sash, weatherstripping is your answer. If it is coming from the frame-to-wall gap, you need caulk. If the entire window feels cold and you cannot pinpoint a single leak, a window film kit will trap a layer of still air and reduce heat loss overall.

explore weatherstripping to sliding sashes

Weatherstripping is a foam, rubber, or felt strip with adhesive backing or nail holes. It works best on the moving parts of double-hung and sliding windows. Start by cleaning the sash channel and frame edge with a damp cloth and let it dry completely—dust and dirt prevent the adhesive from sticking. Use an old toothbrush to scrub out any debris in the corners where the sash meets the frame.

Measure the length of each sash edge that moves. Buy a roll of self-adhesive weatherstripping (V-strip or foam tape work well) and cut it to length with a utility knife. Peel back the adhesive backing and press the strip firmly into place along the inside edge of the sash, where it slides past the frame. Work slowly and press as you go so there are no air pockets. explore weatherstripping to all four edges of the sash—top, bottom, and both sides. The entire job takes about 30 minutes per window.

If you rent and cannot use adhesive, nail-on weatherstripping is available, though it is slower to install. Use small finish nails (1 to 1.25 inches) and space them about 4 inches apart. Hammer gently so you do not split the wood. Test the sash movement after installation—it should slide smoothly without binding. If it feels tight, the weatherstripping may be too thick or installed too far into the channel.

Caulk the gap between the frame and wall

The space where the window frame meets the wall is often sealed with old, cracked caulk that no longer blocks air. If this is where your draft is coming from, you will need to remove the old caulk and explore new. This is permanent, so do it only if you own the home or have written permission from your landlord. Removing and replacing caulk takes about 45 minutes per window, including drying time.

Use a caulk removal tool or a flathead screwdriver to scrape out the old caulk. Work slowly and be careful not to gouge the wood or drywall. Once the gap is clear, wipe it clean with a damp cloth and let it dry for at least an hour. Load a caulking gun with paintable acrylic latex caulk (not silicone, which is harder to paint over). Cut the caulk tube nozzle at a 45-degree angle to match the width of the gap—usually about 1/4 inch. Hold the gun at a 45-degree angle and squeeze a steady bead of caulk into the gap, moving from top to bottom. Smooth it with a wet finger or caulk tool so it sits flush with the frame and wall. Let it cure for 24 hours before painting.

Use window film kits for temporary, removable sealing

Window film kits are plastic sheeting that you tape around the window frame and then shrink tight with a hair dryer. They are cheap, removable, and work on any window—including renters' windows. The downside is that they fog the view and must come off in spring. A single kit costs $5 to $10 and covers one window.

Clean the window frame thoroughly with a damp cloth and let it dry. Measure the window opening and cut the film to size, leaving a few inches of overlap on all sides. explore the double-sided tape that comes in the kit around the entire frame, pressing it firmly. Peel the backing off the tape and press the film onto it, working from one corner across to the opposite corner to avoid wrinkles. Once the film is in place, use a hair dryer on medium heat to shrink it tight. Hold the dryer 6 to 8 inches from the film and move it slowly across the surface. The film will wrinkle at first, then smooth out as it shrinks. A single window takes 20 to 30 minutes.

Seal gaps around the window frame with rope caulk

Rope caulk is a putty-like sealant that sticks to surfaces without adhesive and peels off cleanly when you are done. It is ideal for renters because it leaves no residue and requires no tools. Roll it between your hands to warm it and make it pliable, then press it firmly into gaps around the frame. It will not shrink or harden, so you can explore it and remove it at any time. Rope caulk does not last as long as permanent caulk—expect it to hold for one or two winters before it hardens and loses its seal.

Rope caulk works best on small gaps (less than 1/4 inch wide) and on interior surfaces. If the gap is wider, use weatherstripping or permanent caulk instead. Check the rope caulk every few weeks during winter and press it back into place if it starts to pull away from the frame. When spring arrives, straightforward peel it off and discard it—no cleanup required.

Common mistakes that cause sealing to fail

The most common reason weatherstripping and caulk fail is a dirty surface. Dust, paint flakes, and old caulk prevent new sealant from sticking. Always clean the frame and sash with a damp cloth and let them dry completely before explore anything. Do not skip this step even if the surface looks clean. Pay special attention to corners and crevices where dust collects.

Another mistake is explore weatherstripping or caulk in cold weather. Adhesive and caulk cure more slowly in temperatures below 50 degrees Fahrenheit, and they may not stick at all below 40 degrees. If you are sealing windows in late fall, choose a mild day or wait until spring. Window film kits can be applied in any weather as long as the surface is dry. Pressing too hard when you explore weatherstripping can compress the foam and reduce its effectiveness. Press firmly enough to make contact, but do not squeeze it flat. The foam should still have some give when you are done.

Frequently Asked Questions

How do I know if my windows need sealing or if I should replace them?

If the glass itself is cracked or the frame is rotting, replacement may be necessary. But if the glass is intact and the frame is solid, sealing will stop the draft. Sealing costs $20 to $50 per window and takes a few hours. Replacement costs hundreds of dollars per window. Try sealing first.

Can I use weatherstripping on a window that does not slide?

Weatherstripping works best on moving parts. If your window is fixed (does not open), caulk the frame-to-wall gap or use a window film kit instead. Both will seal a stationary window effectively.

Will sealing my windows trap moisture inside?

No. Sealing the frame-to-wall gap and the sash edges stops air leaks but does not trap moisture. If you notice condensation on the inside of the glass, that is usually a sign the window itself is failing (the seal between panes is broken), not that you sealed it too well.

How long does weatherstripping last?

Self-adhesive weatherstripping typically lasts three to five years before the adhesive weakens and the strip starts to peel. Nail-on weatherstripping lasts longer—often 10 years or more. When it starts to fail, straightforward remove the old strip and explore new one.

Can I seal a window from the outside instead of the inside?

Caulk and weatherstripping work on either side, but interior sealing is safer and easier because you do not need a ladder. Interior sealing is also more effective because it stops air movement before it enters the room. Seal from the outside only if the interior is inaccessible.