How to Seal Windows for Winter: A Complete Guide

If there’s an icy breeze seeping into your home, it’s time to learn how to seal your windows for winter. Drafty windows can lower the internal temperature of your home, making your home less energy efficient. Learn how to seal windows for winter to avoid air leaks and cold drafts.

How to Winterize Windows in 9 Different Ways 

If your insulation method is a little worse for wear, consider redoing it or replacing it with another method entirely. That’s where these nine insulation methods will come in handy. Here’s how to insulate windows for winter, summer, and all year long. 

1. Remove Old Caulk and Apply New Caulk

Remove any damaged caulk and then wipe away any dust or grime from the area where you’ll apply the new caulk. If you’re caulking the exterior, apply a caulk that’s explicitly made for exterior surfaces between the frame and the home’s siding. Use clear caulk or select a color to match the woodwork for interior windows. 

Best Types of Caulk for Winterizing Windows

When it comes to winterizing your windows, the best option is to use silicone caulk. This type of caulk creates a long-lasting seal that can withstand extreme temperature fluctuations with a long lifespan. You can also consider using alternative caulk types like polyurethane, acrylic latex, hybrid, and butyl rubber.

Angi Tip

Avoid adding caulk to the seams where the window frame opens. Otherwise, you’ll caulk the window shut.

Kaitlyn Pacheco

Content Editor, Angi

2. Add Weather Stripping

Photo: iStock / Getty Images

Weather stripping works like caulk, blocking gaps between the glass pane and the frame where chilly or scorching air could seep indoors. Weather stripping is a less permanent solution than caulk, and it doesn’t blend in as easily with your window. However, weather stripping is affordable and easy to install, so it’s still a viable option for insulating a window.

Inspect your weather stripping for signs of damage or loose areas. If the weather stripping around your windows needs replacing, you’ll first have to remove the old weather stripping completely. 

How to Apply Weather Stripping to Windows

1. Use water and mild dish soap to clean the sash where the weather stripping will go.

2. Wipe the area dry with a clean cloth and allow any remaining water to dry over several minutes.

3. Cut the weather stripping to match the length of the area where you will attach it.

4. Remove the protective backing and press the foam’s adhesive layer in place.

Best Types of Weather Stripping for Winterizing Windows

Pressure-sensitive foam weather stripping is the easiest to apply, but you can only add it to areas of the window that do not create friction. (This is because the foam could pull away as the window slides across it.) Or, if you don’t plan to open your windows for a few months during winter, you can use the foam anywhere. It can go in areas like the lower sash, the upper sash, and along the sides of the frame. To install it, use the following steps:

3. Add Window Insulation Film

Although some DIYers debate whether window insulation film is effective, it definitely offers benefits for older windows with single-pane glass. The plastic window film cuts down on cold air entering from the outside while keeping the warm air in your home from leaking outward through the glass. Some people dislike the aesthetic of using window insulation film, so keep that in mind since you’ll be looking at it all season long. 

How to Apply Window Insulation Film

1. Wipe the frame with a damp cloth to remove dust. Allow it to dry.

2. Cut the film to the dimensions of the window frame, leaving a few extra inches on all four sides.

3. Apply two-sided tape to the frame.

4. Remove the protective layer from the tape.

5. With the top side of the two-sided tape now exposed, stick the film to it, leaving a few inches of overhang.

6. Once you attach the film securely on all four sides, run a hair dryer back and forth a few inches from the film to shrink and tighten it, removing wrinkles.

7. Continue warming the film until all wrinkles disappear.

4. Use Bubble Wrap

If you receive packages protected with bubble wrap—and if you can get it away from the kids before they pop all of the bubbles—you can use the bubble wrap to stop window drafts. 

However, this solution won’t look aesthetically pleasing, and you won’t be able to see out of the window. That’s why many DIYers only use this solution if they’re in a pinch or waiting to install a more permanent solution. However, securing bubble wrap with masking tape over the interior face of a window works surprisingly well to insulate windows and prevent heat loss.

5. Create a DIY Draft Stopper

For the quickest and least permanent solution to drafty windows, place a draft stopper along the window sill where cold drafts may be entering. While this idea isn’t a long-term fix, you can create a no-cost DIY draft stopper using household goods. However, the stopper doesn’t work if the air leak originates around the window glass or anywhere along the frame other than the sill.

To save money by making your own draft stopper rather than purchasing one, follow these steps:

1. Cut a piece of fabric a few inches longer than the length of the window sill and wide enough to become a tube.

2. Sew the fabric together on the two long edges. 

3. Sew one end of the fabric shut to create a closed end.

4. Fill a little bit of the tube with unpopped popcorn, gravel, or marbles to provide some weight.

5. Stuff the remainder of the tube with socks, old t-shirts, old towels, or other fabrics.

6. Sew the open end of the tube shut.

7. Place the tube along the sill to try to block any leaking air.

6. Install Storm Windows

Although few people use storm windows in modern homes, they’re still an option for winterizing windows. If your house has single-pane glass windows, they may be able to work with a storm window, which is an extra piece of framed glass that snaps into place on the interior or exterior of the current window. 

The average cost of storm windows is around $8,200, so this isn’t a budget-friendly fix. Plus, you have to match the storm window to the type of window you already have for a perfect fit.

7. Add Window Treatments

When aiming to insulate a window, you can also use interior design to your advantage. For instance, you can add window treatments like thermal curtains, which are thick and cozy and help to keep cold air from getting into your home. You can also opt for energy-efficient window treatments like cellular shades to keep your home comfy all year long.

When choosing new window treatments, do your research before making a purchase so you can get the look you want while also increasing your window’s insulation.

8. Insulate Around Your Windows

If you believe the air leaks are occurring because of poorly fitting windows, you can remove the jambs around the frame and add insulation. After carefully removing the jamb, place insulation in any areas where you see open spaces. Options for insulation materials include:

Fiberglass

You can cut fiberglass batting insulation to fit the gap, and it should block air drafts. Do not ball up the fiberglass, as this reduces its effectiveness.

Spray Foam

You may be able to add expanding spray foam into the gap around the window. Add this foam slowly and carefully, as too much foam could push a loose window out of alignment as it expands.

Draft Snake

Draft snakes are an easy and cost-effective solution to block air leaks around windows and doors. These are fabric tubes stuffed with insulating material, and they can be placed along the bottom edges of windows and doors to prevent drafts. 

You can purchase draft snakes or make your own by sewing a tube of canvas or other durable fabric and filling it with rice, sand, or foam pellets. You can also repurpose old socks or sleeves by filling them with similar insulating materials and sewing or tying them shut.

Honeycomb Shades

Honeycomb shades, also known as cellular shades, are one of the best energy-efficient window treatments available. These are designed with a unique cellular structure that traps air and provides an extra layer of insulation to block out drafts.

Plastic Film Kit

A plastic film kit is a simple and effective solution for insulating drafty windows. Kits include a clear plastic film that is applied to the interior of window frames using double-sided tape. Then, using the heat of a blow dryer, the film is shrunk until it’s completely taut, forming a tight seal to block out cold air.

Here are the steps to install a plastic film kit:

1. Clean the window frame and dry it thoroughly before applying the tape.

2. Measure the length and width of your window frame.

3. Unroll and cut your window film to fit, giving yourself an additional six to eight inches of slack to allow for shrinkage.

4. Apply the double-sided tape around the perimeter of the window frame.

5. Peel off the paper to expose the second sticky side of the tape.

6. Press the plastic film onto the tape, ensuring it covers the entire window.

7. Use a hairdryer to shrink the film until it’s completely taut. 

What to Do Before Winterizing Windows

You shouldn’t start actually insulating a window until you do some prep work. By taking care of these steps beforehand, you’re setting yourself up to maintain your most comfy temp all year long. 

1. Clean Your Windows 

Clean the entire area around the window, including the jamb and sill. Start by wiping away dust with a cloth, then use a gentle household cleaner and a rag to scrub the rest.

2. Find Leaks

Grab a tissue and hold it near the area where you suspect a leak may be. If the tissue moves, that’s where your leak is located. (Just make sure you turn off your fan before you start.)

3. Inspect the Caulking

Check both the interior and exterior of the window where it joins your home. Plan to replace any caulking that’s peeling, curling, or missing completely. 

4. Fix Broken Glass

Broken glass in your windows will affect the ability to keep cold drafts out of your home. On average, the cost of window repair typically ranges from $40 to $100 for fixing a cracked pane and from $200 to $500 for replacing window glass. Replacing cracked glass also provides an aesthetic benefit, making it worth the investment during any season.

We strongly recommend hiring a pro for this job, as it can be dangerous and potentially costly with one small misstep. However, if you do have some window repair experience under your belt and feel 100% confident in your ability to remove and repair broken glass yourself, try following these steps:

1. Put on safety equipment: Grab a pair of safety goggles and put on a long-sleeve shirt, full-length pants, cut-resistant gloves, and sturdy closed-toe shoes. Some experts also recommend wearing earplugs to protect your eardrums. 

2. Apply duct tape: Using duct tape, create an X in the middle of the pane to safely hold the glass together in case it breaks further.

3. Remove the broken pane: Remove the caulk or putty holding the pane in place. Carefully wiggle the pane out of the frame.

4. Prepare the pane: If you purchased a new pane, it should be ready to install with no prep work. If you want to repair the cracked frame, apply epoxy to it.

5. Install the pane: Place the pane inside the blank space in the window. Use caulk or putty to secure the pane to the frame. 

5. Measure Your Windows 

Measure the distance between the inside edge of the side jambs horizontally and between the inside of the head jamb and the sill vertically. Take three total measurements in each direction (top, middle, and bottom OR right, middle, and left).

DIY vs. Hiring a Pro

Insulating windows is pretty easy for the most part, so it’s a project that most handy DIYers can easily and quickly tackle themselves, saving money in the process. However, this only applies to the simpler methods of insulating windows, like adding new caulking, using bubble wrap, adding weather stripping, or making a DIY draft stopper. 

More in-depth fixes, like installing storm windows or repairing broken glass, can be difficult, costly, and potentially dangerous, so they’re better left to the pros. After all, you wouldn’t want to embark on an expensive fix just to make a small mistake and have to pay the cost again, plus labor. For these fixes, you’re better off reaching out to a window company near you.