To replace old window weatherstripping, identify your window type, remove the worn material and any leftover adhesive, clean and dry the surface, then install new weatherstripping designed for that window’s moving parts. Measure carefully and choose a product that seals when the window is closed but still lets it open and close smoothly. Most windows take 30 to 60 minutes each.
Weatherstripping is the flexible material installed around the moving parts of windows and doors to reduce drafts and help keep conditioned air inside your home. When it flattens, cracks, or falls off, you’ll often feel it before you see it.
Quick Answer
- Confirm the leak is at the moving parts of the window, not around the fixed frame.
- Identify the window type and existing weatherstripping style.
- Measure each section and add about 10% extra.
- Remove old weatherstripping and scrape off adhesive.
- Clean with mild soap and water, then let it dry completely.
- Install the new weatherstripping, pressing firmly or fastening as directed.
- Open and close the window to test fit and seal.
Signs Your Window Weatherstripping Needs Replacing
- You feel a draft near the window on a windy or cold day.
- You can see daylight around the sash when the window is closed.
- The window rattles in the wind.
- The weatherstripping is cracked, brittle, flattened, or peeling off.
- A strip of paper slides out easily when closed in the window gap.
Weatherstripping or Caulk: Which Do You Need?
This distinction saves a lot of frustration. According to the U.S. Department of Energy, caulk is generally used for cracks and gaps between stationary components, such as where the window frame meets the wall, while weatherstripping seals components that move, like the sash of an operable window. If the draft comes from around the trim, you probably need caulk rather than weatherstripping.
Common Types of Window Weatherstripping
| Type | Where It Works Best | Notes |
|---|---|---|
| V-strip (tension seal) | Side channels of double-hung and sliding windows | Folded vinyl or metal that springs open to seal; durable and hidden when installed |
| Foam tape | Top and bottom of sashes, irregular gaps | Easy to install; closed-cell foam generally holds up better than open-cell foam |
| Rubber (EPDM) tape or profiles | Casement windows and sash contact points | Flexible and weather-resistant; available in D, P, and E shapes for different gap sizes |
| Tubular gasket | Bottom of sashes and larger gaps | Seals well but can be more visible |
| Pile (brush) weatherstripping | Sliding windows and tracks | Fits into grooves on many sliding windows; buy by pile height and backing width |
| Felt | Low-friction, low-cost temporary fixes | Inexpensive but generally less durable and less effective |
The DOE’s weatherstripping guide recommends choosing a type that can handle the friction, weather, temperature changes, and wear of its specific location.
What You Need
- Replacement weatherstripping suited to your window type
- Tape measure
- Scissors or tin snips
- Putty knife or plastic scraper
- Mild soap, water, and a clean rag
- Rubbing alcohol (helps adhesive-backed products bond, if the manufacturer recommends it)
- Small nails or staples and a hammer, for some V-strip products
- Work gloves and safety glasses
Step-by-Step Guide
Step 1: Find Exactly Where Air Is Leaking
On a windy day, move your hand slowly around the closed window. You can also hold a lit incense stick near the edges and watch the smoke; if it wavers or gets pulled, air is moving. Keep flames away from curtains and blinds. Note whether leaks are at the sides, bottom, top, or meeting rail, which is where the two sashes of a double-hung window meet.
Step 2: Identify the Window Type
- Double-hung or single-hung: sashes slide up and down. Leaks often appear in the side channels, at the bottom, and at the meeting rail.
- Sliding windows: sashes move sideways, usually sealed with pile weatherstripping in a groove.
- Casement windows: crank outward and seal by pressing against a gasket around the frame.
If your windows are newer vinyl or aluminum units with factory weatherstripping in grooves, look for the manufacturer’s name on the frame or glass. Replacement parts are often available by model.
Step 3: Measure
Measure each section where you’ll install weatherstripping. The DOE suggests adding the perimeters of windows you plan to weatherstrip and adding about 10% for waste. Also note the gap size, since weatherstripping that’s too thick can keep the window from closing and too thin won’t seal.
Step 4: Remove the Old Weatherstripping
Peel off adhesive strips and pry out tacked strips gently with a putty knife. Scrape off leftover adhesive and foam residue. For grooved pile weatherstripping, you can often pull the old strip out from one end.
If your home was built before 1978, window sills and sashes are friction surfaces where lead-based paint can wear into dust. Avoid dry scraping or sanding painted surfaces, and clean up with damp methods.
Step 5: Clean and Dry the Surface
Wash the area with mild soap and water, rinse, and let it dry completely. Adhesive-backed products bond poorly to dust, grease, and moisture. Many adhesives also work best when installed in mild, dry weather, so check the product’s temperature guidance.
Step 6: Install the New Weatherstripping
For V-strip in double-hung channels: open the sash fully, cut strips to length, and slide them into the side channels with the open side of the “V” facing outdoors so wind presses it more tightly closed. Fasten according to the product instructions, using adhesive backing or small nails.
For foam or rubber tape at the bottom sash: apply to the underside of the lower sash so it compresses when the window closes. Press firmly along the whole length.
For the meeting rail: a thin V-strip or foam tape on the upper sash’s bottom rail can help seal where the two sashes meet.
For casement windows: apply rubber gaskets to the frame where the sash presses when closed.
For sliding windows: slide new pile weatherstripping into the groove and trim to length.
Step 7: Test the Window
Open and close the window several times. It should close fully and lock without excessive force. Repeat the draft test. If the window now binds, the weatherstripping may be too thick.
Common Mistakes to Avoid
- Using weatherstripping where caulk is needed. Stationary gaps need caulk.
- Stretching foam tape while applying. It shrinks back and leaves gaps.
- Installing on a dirty or damp surface. Adhesive fails quickly.
- Choosing material that’s too thick. The window may not latch, which makes the draft worse.
- Blocking weep holes. Many windows have small drainage openings at the bottom of the frame. Keep them clear.
When You Should Call a Professional
Consider professional help if frames are rotted, sashes won’t move or stay open, balance systems in double-hung windows are broken, or double-pane glass is fogged between the panes. If drafts persist throughout the house despite new weatherstripping, a professional energy assessment can find hidden air leaks. For more on DIY limits, see DIY vs. hiring a professional.
How to Keep Weatherstripping Working Longer
- Inspect it every fall as part of your seasonal home maintenance checklist.
- Clean window tracks and channels so grit doesn’t wear the seals.
- Avoid painting over weatherstripping, which stiffens it.
- Re-caulk exterior trim when it cracks. Our guide on re-caulking covers technique that applies to many surfaces.
Frequently Asked Questions
How often should window weatherstripping be replaced?
It depends on the material and exposure. Foam tape may need replacement every few years, while vinyl, rubber, and metal products usually last longer. Replace it whenever it’s cracked, flattened, or no longer sealing.
What is the best weatherstripping for old windows?
For older double-hung wood windows, V-strip in the side channels and foam or rubber at the bottom sash are common choices. The best option depends on the gap size and how the window moves.
Can I weatherstrip windows in the winter?
You can, but adhesive-backed products may not bond well in cold temperatures. Check the manufacturer’s temperature range, or use products that fasten mechanically.
Will weatherstripping lower my energy bill?
Sealing air leaks can reduce heating and cooling losses and improve comfort. How much you save depends on how leaky the home was to begin with and where the biggest leaks are.
Is it the same process for doors?
The principles are similar, but doors typically use jamb weatherstripping plus a door sweep at the bottom. If a door stops closing after new weatherstripping, see how to fix a door that won’t close properly.
Final Thoughts
Replacing window weatherstripping is one of the most satisfying small projects in a house: inexpensive, quick, and noticeable the next cold or windy day. Take the time to identify the right type, clean the surface well, and test the fit. It’s a skill worth adding to your list alongside the other home repairs every beginner should learn.