How to Seal Windows for the Winter

When cooler temperatures become the norm, it’s time to seal your windows for the winter. 

Leaky windows are responsible for as much as 30% of heat loss. So, if your windows are 15+ years old, single pane, or feel cold to the touch, you need to seal them.

How to Seal Windows for the Winter

There are many ways to seal a window, each with varying difficulty levels and at different price points. Here are the top ways to keep heat from escaping your windows without replacing them.

Insulate Your Windows with Plastic Film

Window insulation kits are the easiest and least expensive way to block drafts and keep heat inside. These kits contain double-sided tape and sheets of plastic.

To use them, place the tape around your window frame (inside your home.) Then cut a plastic sheet to size and smooth the edges over the tape.

Use a hairdryer to shrink the plastic and remove wrinkles. Repeat on all windows.

In addition to the traditional plastic window insulation kits, you can purchase magnetic versions. Magnetic window insulation kits come with a magnetic strip that goes around your window. The thick plastic sheets come equipped with magnets that connect to your window frame.

The downside is since you can open and close the magnetic windows insulation kits, they don’t provide a tight seal like the traditional tape kits.

Seal the Outsides of Windows with Caulk

If you notice a draft around your window frame, seal the outside of the windows with caulk. Caulk will plug small holes, stopping heat from leaking out of your windows.

For this project, you’ll need exterior caulk in clear or a color that matches your window frame, a caulk gun, and a utility knife. Here’s what to do:

  • Use a utility knife to remove old caulk from around the exterior window frame 
  • Load the new caulk in the caulking gun, and cut a small hole in the tip
  • Apply the new caulk between the window frame and siding

It will take the caulk several hours to cure. Repeat this process on all drafty windows or those with deteriorating caulk.

Weather Strip Your Windows

Sometimes, the cause of heat loss is tiny gaps around the window frame. An easy fix is weather stripping.

Weather stripping comes in rolls of foam, felt, or rubber. Some weather stripping is self-adhesive, while other types require nails. Weather stripping can go around a window frame, jamb, tracks, or anywhere else you need to plug an air leak.

Aside from weather stripping, you can use weather tape over the lower sash where the window shuts. 

Install Cellular Shades and Thermal Curtains

A thick cellular shade or blackout curtain helps to insulate a window, keeping cold air out of the house. The added insulation also protects the window from excess condensation problems.

According to the Department of Energy, cellular shades reduce window heat loss by as much as 40%, equating to a 10% savings on your heat bill. Plastic-backed curtains can help reduce heat loss by another 10%.

Use a Draft Stopper

Draft stoppers look like long, snake-like stuffed animals. While they won’t plug all air leaks, they’re great for stopping drafts at your window sill.

You can place a draft stopper on the lower or upper portion of the window sash to insulate and prevent leaks.

Purchase Storm Windows

Storm windows are ideal for older, single-pane windows. They stop air leaks and can save you 10 to 30% on your energy bills. 

You can purchase storm windows that go on the inside or outside of your window frame. The average storm window costs $75 to $200 per window.

Frequently Asked Questions (FAQ)FAQ

Can I use plastic wrap to insulate my windows?

You can use a plastic wrap, like Saran wrap, over your windows, but it’s not quite as thick as what comes in window insulation kits, so it won’t insulate as well.

How do you seal windows from the outside?

The best way to seal windows from the outside is to apply a new bead of caulk around the window. Another option is to add storm window inserts.

Can you caulk the inside of your window?

If you’re trying to seal your windows for the winter, you can caulk the inside as long as you use a removable caulk. If you use a permanent caulk, it will be hard to remove and may damage your window trim or finish.

What’s the cheapest way to insulate windows for the winter?

Try plastic window insulation film or bubble wrap if you’re looking for a low-cost way to insulate your windows. 

Final Thoughts

If you’re looking for the best way to seal your windows for the winter – it depends. If your windows have old caulking on the outside, replacing the caulking is a good start. You can add window insulation film or storm windows over top of old, single-pane windows to increase energy efficiency.

And don’t forget the value of simple things like adding thick curtains and cellular shades. Window coverings can reduce heat loss by as much as 40 percent.