Frost crystals spreading across the inside of a cold window pane

Best Window Weatherstripping

There is no best weatherstripping. There is the product that fits the gap you have, and three different gaps around every window.

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Written by Ellen Barrow Exteriors editor

Published

Updated

Start with the answer

Find the window gap before the product

There is no best window weatherstripping, only the right product for the gap, and one question settles most of it: is the gap one that moves, one that does not, or the glass itself. Buying for the wrong gap is the usual reason a draught survives an afternoon of work and a bag of receipts.

Every window has three places air gets through, and they need three different things. The moving joint, where the sash slides or swings against the frame, needs weatherstripping that compresses and springs back thousands of times. The fixed joint, where the frame meets the wall, needs caulk, because nothing there is supposed to move. And the glass itself is not a gap at all: it is simply cold, and the answer there is another layer of still air in front of it.

Work out which of the three you have before you buy anything. A lit candle or an incense stick held near the frame on a windy day will find a moving-joint leak in seconds. A draught you feel only at the trim, with the sash locked, is the fixed joint. And a window that is not draughty but is cold to sit beside is a glass problem, which no amount of weatherstripping touches.

Every figure below is published by the manufacturer or the retailer, with the source and the date it was checked under each entry. There are no prices on this page: they move week to week, and a number we cannot stand behind is worse than a link that shows you the current one.

Side by side

What each weatherstripping type is for

The whole guide in one table: the gap it seals, the format it comes in, and the figure the manufacturer publishes. Read down the "best for" column first, then go to the entry that matches the gap you found.

Product Best for Type Published figure
Frost King V-Seal Weatherstrip Double-hung side channels Folded vinyl tension seal, self-adhesive Folded vinyl V-strip on a self-adhesive backing, cut to length with scissors.
M-D Building Products Silicone Bulb Weatherstrip Casement and awning windows Silicone bulb seal, self-adhesive Hollow silicone bulb on a self-adhesive flange.
Frost King EPDM Rubber Foam Tape Wide or uneven compression gaps Closed-cell EPDM foam tape, self-adhesive Closed-cell EPDM rubber foam tape on a self-adhesive backing.
GE Advanced Silicone 2 Window & Door The exterior frame joint 100% silicone sealant, cartridge 100% silicone, with no latex content.
DAP Alex Plus Acrylic Latex Caulk Plus Silicone Interior trim you will paint Acrylic latex with silicone, cartridge Acrylic latex with added silicone for flexibility.
Frost King Rope Caulk A seal you take off in spring Removable putty rope, no cure Pre-formed putty rope, separated into strands by hand.
3M Indoor Window Insulator Kit Single glazing and cold rooms Heat-shrink film kit, one winter Clear film plus double-sided tape, shrunk taut with a hairdryer.

Temperature ranges are the manufacturer’s stated application or service range, and every one of them assumes a clean, dry surface. Weatherstripping applied to a dusty or damp frame in the cold is the single most common reason an adhesive product is back off within a month.

The picks

Seven weatherstripping products, three window gaps

The moving joint

Weatherstripping where the sash meets the frame

Folded vinyl tension seal, self-adhesive

Best for a sash that slides Frost King V-Seal Weatherstrip

The default for a double-hung or slider, and the only common format that seals a joint the sash has to move through. It folds into a V and springs open against the channel, so the sash still runs while the gap is closed. Fitted inside the channel it is invisible once the window is shut, which is why it survives on windows people actually use.

Format
Folded vinyl V-strip on a self-adhesive backing, cut to length with scissors.
Gap range
Rated for gaps up to 3/16 inch.
Application
Applied above 20°F to a clean, dry surface.
Where it goes
Inside the sash channels and along the meeting rail of a double-hung.

What it does well

  • The sash still opens and closes normally, which foam tape cannot promise.
  • Invisible from the room once the window is shut.
  • Cuts to length with scissors and needs no tools at all.

What it does badly

  • Useless on a gap wider than about 3/16 inch; measure before buying.
  • The adhesive is the weak point, and it will not take on a dusty or freshly painted channel.
  • Fiddly to fit on a window with worn, uneven channels, which is exactly where you want it.
Check the price at The Home Depot

Figures from Frost King V-Seal product listing Checked August 12, 2026

Silicone bulb seal, self-adhesive

Best for a sash that closes against a stop M-D Building Products Silicone Bulb Weatherstrip

A hollow silicone tube that squashes flat when the sash closes onto it, which is what a casement, an awning or a hinged door needs. Silicone stays flexible at temperatures that make vinyl brittle and foam crumble, so this is the one to buy where the window faces real winter or gets hard sun.

Format
Hollow silicone bulb on a self-adhesive flange.
Service range
Stays flexible from around minus 40°F to 400°F.
Compression
Seals against a stop when the sash closes onto it; not for a sliding joint.
Where it goes
On the stop of a casement, awning or hopper window, and on hinged doors.

What it does well

  • Silicone does not harden in cold or perish in sun, unlike vinyl and foam.
  • The hollow bulb seals a wider and less even gap than a V-strip will.
  • Recovers its shape after years of being squashed shut.

What it does badly

  • The most expensive weatherstrip per foot on this page.
  • Wrong for a sliding sash: the bulb drags and tears.
  • Nothing paints onto silicone, so the colour you buy is the colour you keep.
Check the price at Amazon

Figures from M-D Building Products silicone weatherstrip listing Checked August 12, 2026

Closed-cell EPDM foam tape, self-adhesive

Best for a gap nothing else fits Frost King EPDM Rubber Foam Tape

The blunt instrument, and sometimes the right one. Closed-cell EPDM foam compresses further than a V-strip or a bulb, so it closes the wide, uneven gap you find at the bottom of a sash or under a window air conditioner. Use it where the joint compresses rather than slides, and accept that it is visible.

Format
Closed-cell EPDM rubber foam tape on a self-adhesive backing.
Compression
Suits gaps wider than a V-strip will close; compresses to a fraction of its thickness.
Water
Closed cell, so it does not soak up water the way open-cell foam does.
Where it goes
Sash bottoms, attic hatches, window air conditioner surrounds.

What it does well

  • Closes gaps too wide or too uneven for any tension seal.
  • Closed-cell EPDM outlasts the cheap open-cell foam sold beside it.
  • The easiest product on this page to fit correctly.

What it does badly

  • Visible on the window, which V-strip inside a channel is not.
  • Wrong for a sliding joint: it shears off.
  • Compresses permanently over a season or two and needs replacing more often than a bulb seal.
Check the price at The Home Depot

Figures from Frost King rubber foam tape listing Checked August 12, 2026

The fixed joint

Caulk where the window frame meets the wall

100% silicone sealant, cartridge

Best for sealing the outside, permanently GE Advanced Silicone 2 Window & Door

For the joint between the window frame and the wall on the outside, where the seal has to survive rain, UV and thirty years of the wall moving. Silicone stays flexible and does not shrink back the way acrylic latex does. The trade-off is permanent: silicone cannot be painted and nothing else will bond over it.

Chemistry
100% silicone, with no latex content.
Movement
Rated for permanent flexibility; does not shrink or crack as it ages.
Water
Rain-ready in around 30 minutes on the manufacturer’s stated conditions.
Paint
Cannot be painted. Buy the colour you intend to see.

What it does well

  • Outlasts acrylic latex on an exterior joint by a wide margin.
  • Stays flexible through the seasonal movement that cracks cheaper sealants.
  • Waterproof quickly enough to use on a day with rain coming.

What it does badly

  • Unpaintable, permanently, which rules it out on an interior joint you want to disappear.
  • Nothing bonds to cured silicone except more silicone, including future repairs.
  • Harder to tool to a clean line than latex; it is not forgiving of a slow hand.
Check the price at Lowe’s

Figures from GE Advanced Silicone 2 product page Checked August 12, 2026

Acrylic latex with silicone, cartridge

Best for the inside joint DAP Alex Plus Acrylic Latex Caulk Plus Silicone

The interior counterpart to the silicone above, and the difference that matters is paint. Alex Plus takes paint, tools to a clean line with a wet finger, and cleans up with water, so it disappears into painted trim. Do not use it outside on a joint that moves; that is what the silicone is for.

Chemistry
Acrylic latex with added silicone for flexibility.
Paint
Paintable, typically within about 30 minutes of application.
Cleanup
Water, while wet.
Where it goes
Interior trim, casing and the joint between frame and drywall.

What it does well

  • Paints over cleanly, which silicone never will.
  • Tools to a sharp line and cleans up with a damp cloth.
  • Forgiving to apply, which matters across twenty feet of trim.

What it does badly

  • Shrinks slightly as it cures, so a deep joint may need a second pass.
  • Not the right product for an exterior joint that moves with the seasons.
  • Less durable than silicone anywhere that gets direct weather.
Check the price at The Home Depot

Figures from DAP Alex Plus product page Checked August 12, 2026

Removable putty rope, no cure

Best for a window you seal shut for winter Frost King Rope Caulk

A rope of putty you press into a joint with your thumb and pull out again in April. It never cures, so it is the honest answer for a window you do not open in winter and do want to open in summer, and for renters who cannot caulk anything permanently.

Format
Pre-formed putty rope, separated into strands by hand.
Cure
None. It stays pliable and is removed by pulling it off.
Season
Intended as a seasonal seal, applied in fall and removed in spring.
Tools
None. Applied with thumb pressure.

What it does well

  • Completely removable, with no residue on a sound painted surface.
  • No cure time, no smell, and nothing to clean up.
  • The only product here a renter can use on a window without asking.

What it does badly

  • Seals the window shut. That is the point, and it is a fire-egress consideration on a bedroom window.
  • Visible: it reads as a bead of grey or white putty on the frame.
  • Can leave a mark on bare or aged wood, so test a short length first.
Check the price at Amazon

Figures from Frost King rope caulk listing Checked August 12, 2026

The glass

When the window is not leaking air, only cold

Heat-shrink film kit, one winter

Best for a window that is cold rather than draughty 3M Indoor Window Insulator Kit

Not weatherstripping at all, and the right answer to a problem weatherstripping cannot solve. A film taped across the opening and shrunk tight with a hairdryer traps a layer of still air in front of the glass, which is exactly how a double-glazed unit works. On single glazing it changes how a room feels more than any seal on this page.

Format
Clear film plus double-sided tape, shrunk taut with a hairdryer.
Season
One heating season. Removed and discarded in spring.
How it works
Traps still air between film and glass, the same principle as a sealed glass unit.
Where it goes
Single-glazed windows, cold rooms, and any window that will not be opened until spring.

What it does well

  • The only product here that addresses cold glass rather than a gap.
  • Nearly invisible once shrunk taut, unlike the cheaper kits.
  • Cheapest meaningful improvement available on a single-glazed window.

What it does badly

  • The window cannot be opened all winter.
  • One season only: the film is not reusable.
  • The tape can lift paint on removal, particularly on older interior trim.
Check the price at Amazon

Figures from 3M indoor window insulator kit listing Checked August 12, 2026

How to choose

How to choose window weatherstripping

Work through these in order. The first two decide which of the three gaps you have, and the gap decides the product.

  • Lock the window and hold a lit incense stick near the frame on a windy day. If the smoke pulls at the sash, it is the moving joint. If it pulls at the trim, it is the fixed joint.
  • Is the joint one the sash has to move through, or one it closes onto? Sliding joints need a V-strip; compression joints take a bulb or foam.
  • Measure the gap before you buy a tension seal. A V-strip does nothing in a gap wider than about 3/16 inch, and that is the most common wasted purchase in this category.
  • Inside or outside, for caulk? Outside wants silicone and stays unpainted. Inside wants acrylic latex and disappears under paint. Using one where the other belongs is why so much caulk is cracked or peeling.
  • Do you need the window to open before spring? If yes, rope caulk and film are both off the table for that opening.
  • Is the window actually draughty, or just cold to sit beside? A cold window with no air movement is a glass problem, and no amount of weatherstripping will change it.

How we pick

How this weatherstripping guide is put together

Every figure on this page comes from a manufacturer data sheet or a retailer listing, and each entry names its source and the date it was checked. Where a number is not published, this guide says so rather than estimating it.

Nobody can pay to appear here, and no entry moves up for a better commission rate. The links can earn a commission when the affiliate programmes behind them are live, at no cost to you, and that arrangement is set out in full on our affiliate disclosure page.

  • Products are grouped by the gap they seal, not ranked. Seven entries, three different problems, because a single winner would be wrong for most readers.
  • No prices are published. They change weekly and a stale figure would make the whole page look untended.
  • Nothing here has been laboratory-tested by us. What this guide does is read the data sheets, match the product to the gap, and say plainly what each one is bad at.

Draught questions

What homeowners ask about sealing windows

How do I find where a window is leaking air?

Close and lock the window, then move a lit incense stick or a candle slowly around the frame on a windy day and watch the smoke. It will pull toward the leak. Do it on the sash line first, then the trim, because those two findings send you to completely different products.

Will weatherstripping save me money?

On a genuinely draughty window, yes, and it is one of the highest returns per dollar available in a house. On a sound modern window with no measurable air movement, no. Find the leak before you buy the fix, or you are sealing a joint that was already sealed.

Should I weatherstrip or replace the windows?

Weatherstrip first, always. It costs a rounding error against replacement, it takes an afternoon, and it tells you how much of the discomfort was air movement rather than cold glass. If the room is still cold with the draughts gone, that is a glass problem and a replacement conversation.

Why does my weatherstripping keep falling off?

Almost always the surface. Adhesive-backed strip needs a clean, dry, non-chalky surface above about 20°F, and window channels are dusty by definition. Wipe with rubbing alcohol, let it dry fully, and fit it in a warm room rather than on a January morning.

Can I caulk a window shut?

You can, with rope caulk, and it is a legitimate seasonal answer for a window you will not open. Do not do it to a bedroom window that serves as fire egress, and do not use a curing caulk anywhere you want to open again.

Is window film worth it?

On single glazing, more than anything else on this page. On an existing double-glazed window it adds very little, because the still-air layer it creates is the one the window already has. Judge it by what you are starting from.

Specifications on this page are the manufacturer’s or the retailer’s published figures, checked on the date shown under each product. Prices are deliberately not published here: they move week to week, and the link carries the current one. Nothing on this page has been laboratory-tested by Home Palais.

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