Winter Window Sealing: The Ultimate Guide

If you’re feeling a chill inside, it might be time to learn how to properly seal your windows for winter. Drafty windows let in cold air, making your home less energy-efficient and harder to keep warm. Here’s how to seal your windows and stop those chilly drafts.

How to Winterize Windows: 9 Effective Methods

If your current insulation is outdated or ineffective, consider trying one of these nine methods to ensure your windows are properly winterized.

1. Replace Old Caulk and Apply Fresh Sealant

Start by removing any cracked or damaged caulk and cleaning the area thoroughly. Once the surface is clean, apply fresh caulk to seal the gaps. If you’re caulking the exterior, use a product designed for outdoor use, like silicone, which holds up well against weather extremes. For interior caulking, clear or color-matching caulk works best.

Best Types of Caulk for Winterizing Windows
Silicone caulk is the top choice for creating a durable, long-lasting seal. It’s perfect for extreme temperature fluctuations. Alternatives like polyurethane, acrylic latex, or butyl rubber are also great options.

2. Install Weather Stripping

Weather stripping is a temporary yet effective way to seal air leaks between the window glass and frame. It’s easy to install and budget-friendly, though it doesn’t blend seamlessly with the window like caulking does.
Inspect your current weather stripping for signs of wear or damage, and replace it if needed.

How to Apply Weather Stripping

• Clean the sash area with water and mild dish soap.
• Dry the area thoroughly.
• Cut the weather stripping to the appropriate length and apply it to the frame.
• Press the adhesive side into place and ensure it’s secure.

Best Types of Weather Stripping
Pressure-sensitive foam is the easiest to apply, although it works best in areas where the window won’t slide. For windows that won’t be opened during the winter, foam weather stripping can go anywhere around the frame.

3. Use Window Insulation Film

For single-pane windows, insulation film can be a game-changer. While not the most aesthetic solution, it helps trap warm air inside and keep cold air out. It’s especially useful for older windows.
How to Apply Window Insulation Film

• Clean the window frame with a damp cloth and dry thoroughly.
• Cut the film slightly larger than the window dimensions.
• Attach double-sided tape to the frame, peel off the backing, and stick the film in place.
• Use a hair dryer to shrink the film until it’s taut and wrinkle-free.

4. Bubble Wrap for a Temporary Fix

Bubble wrap, though not the most attractive solution, can work wonders in insulating windows. It’s particularly effective for windows that won’t be opened throughout the winter.
Simply tape bubble wrap over the window’s interior surface to block drafts.

5. DIY Draft Stoppers

A quick and easy way to reduce drafts is by placing a DIY draft stopper on the window sill. This can be made with items you already have at home, such as fabric, old t-shirts, and even popcorn kernels or marbles for weight.
How to Make Your Own Draft Stopper

• Cut fabric to a size that fits the window sill.
• Sew the fabric into a tube, leaving one end open.
• Fill the tube with fabric scraps or weighted materials.
• Sew the open end shut and place the stopper along the sill.

6. Install Storm Windows

Storm windows are a more permanent solution for single-pane windows. These additional layers of glass create an insulating barrier that helps maintain indoor temperatures. While the installation can be costly (around $8,200 on average), storm windows are effective at blocking drafts and improving energy efficiency.

7. Add Insulating Window Treatments

Window treatments like thermal curtains or cellular shades (honeycomb shades) can add an extra layer of insulation. Thermal curtains help keep cold air out, while energy-efficient cellular shades trap air in their cells for added insulation.

8. Insulate Around the Window Frame

If air leaks are coming from gaps around the window frame, consider adding insulation to fill these spaces.

• Fiberglass Insulation: Cut to fit gaps around the window frame to block drafts.
• Spray Foam: Expanding spray foam can be applied carefully into gaps, but don’t use too much or it could misalign the window.
• Draft Snakes: These simple, cost-effective fabric tubes filled with insulating materials can be placed at the base of windows to block drafts.

9. Use a Plastic Film Kit

Plastic film kits are a simple way to create an airtight seal around your windows. These kits typically include a clear plastic film that attaches to the window frame with double-sided tape and can be shrunk using a hairdryer to tighten the seal.

Steps to Install a Plastic Film Kit

• Clean the window frame and dry it.
• Measure the window and cut the film to size, leaving extra material for shrinkage.
• Apply double-sided tape around the frame.
• Attach the film, press it into place, and use a hair dryer to shrink it.

Prep Work Before Winterizing Your Windows

Before you begin insulating, take a few necessary steps to prep your windows:

1. Clean the Area Around the Window
   Wipe away dust, dirt, and grime from the frame, jamb, and sill using a gentle cleaner.
2. Find the Leaks
   To detect leaks, hold a tissue near areas you suspect to be drafty. If the tissue moves, you’ve found the leak.
3. Inspect Existing Caulking
   Check the caulking around your windows for signs of damage. If it’s peeling or missing, replace it to seal any gaps.
4. Fix Broken Glass
   Cracked glass will compromise your window’s ability to keep cold air out. If you have broken glass, consider replacing it. Window repair costs range from $40 to $100 for minor cracks, or $200 to $500 for full glass replacements.
5. Measure Your Windows
   Accurate measurements are crucial if you’re buying weatherstripping or insulation film. Measure the height and width of the window frame, making sure to take multiple measurements (top, middle, bottom, and left, right, center) for accuracy.

DIY vs. Professional Help

While many window-insulating methods are easy enough for DIYers—such as applying caulk, weather stripping, or insulation film—some projects, like replacing broken glass or installing storm windows, are more complex and might be better handled by professionals. DIY fixes save money, but for major repairs, calling in an expert can prevent mistakes and unnecessary costs down the line.

By following these tips and prepping your windows properly, you’ll be able to keep the cold air out and your heating bills lower all winter long!