How to Insulate Your Apartment Windows for Winter

If you’re wondering where that draught is coming from inside your cozy home, then the most likely culprit is your windows. Instead of spending a fortune on new windows (or sweaters! ), you can efficiently insulate your draughty windows to keep the heat in winter.

Locking your windows for the winter is a low-cost, no-hassle way to keep cold air out of any gaps or cracks. It also controls the surface temperature of your window to prevent condensation build-up, which would occur if you turned up your heating.

Furthermore, knowing how to insulate your windows for winter will help you save money on heating bills because you won’t be losing heat. And the best thing is that there are numerous simple and inexpensive ways to insulate your windows.

When Should You Insulate Your Windows?

Ideally, it would be best to insulate your windows before the cold weather arrives. However, because it is difficult to assess the state of your windows’ insulating abilities when the temperatures are equal both inside and outside, you may want to wait until it is time to turn on the heat or air conditioner.

The majority of these window insulation techniques are not expensive. Be it shrink-fit window film insulation, caulking, weatherstripping, or spray foam are all so cheap that you can recoup your investment in energy savings in just one or two seasons. Installment of energy-efficient window treatments is the most expensive of the steps; they can cost up to 25% more than standard, non-thermal window curtains.

Recognizing Window Insulating Materials

Understanding how and why an insulating product or material works around a window can be beneficial. Before you begin insulating your windows, make sure you know the specifics of the item you intend to use.

Insulating Window Film

Transparent window film works best in the summer to reduce solar heat passing through the glass, while some films retain room heat in the winter. The film is supplied in large sections cut to fit the window during installation. Double-sided tape is used to secure the film to the outside of the interior window frame. Tighten the film by lightly blowing warm air over it with a hairdryer. The dead space or air pocket created between the film and the window acts similarly to that of argon or krypton gas that fills the space between double-glazed window panes, preventing air and thermal infiltration.


Caulk is inexpensive and simple to use. All caulk must be reapplied regularly, especially if the window area expands and contracts. Expect to strip away and re-caulk these areas after only a year or two.

There are three kinds of caulk for various surfaces. Use water-based latex caulk for window sash cracks or around the 1/4 inch or less wide. Silicone-based caulk is ideal for metal and glass surfaces but cannot be painted. For sections that will be painted, use paint-quality caulk.


Weatherstripping is simple to install and remove, leaving no residue or mess behind. Often, this is an acceptable solution because windows are usually closed during the winter. Note that the window cannot be opened or closed when applied to movable window parts. If you want to open the window, you must first remove the stripping.

EPDM, foam, or felt weatherstripping can be used to fill gaps around stationary parts in or around windows. Weatherstripping can also be used to temporarily fill the gap between the sash and the window frame. Remember to weatherstrip areas where cold air can easily enter, such as your garage.

Foam Spray

Spray foam can quickly expand out of the wall cavity and onto the wall or floor and is difficult to control, so buy low-expansion foam for window insulation and protect areas where you don’t want the foam to stick. Only gaps around the window frame that are large and easily accessible should be filled with expandable spray foam. With the help of a long nozzle, Spray foam can reach areas that fiberglass insulation cannot.

Window Treatments that Save Energy

Insulating window treatments typically come in two varieties: thick side-drawn draperies and vertically-drawn cellular shades. Insulating draperies and shades are only effective when they are closed.

Draperies are thicker than ordinary curtains and have tie-backs to keep them against the wall, preventing further air infiltration. During the summer, draperies with white plastic backings can significantly reduce the heat in the home.

When open, pleated-style shades that are vertically opened and closed may appear mini-blinds. When they are down and locked, however, you can see that their cellular construction creates air pockets to aid in the maintenance of indoor temperatures.

Also See: Tips To Weatherize Your Home

Draft Deterrents

Fabric draught stoppers, also known as draught snakes, are commonly used to close gaps under doors. They can also close the gap between the bottom of the window sash and the window frame. Draft snakes have few drawbacks because they are inexpensive and simple to make or buy. Remember that they only block one of four potential draught points along the perimeter of a window sash. They are also effective at soundproofing.

Benefits of Insulating Windows

Improving your home’s energy infrastructure will reduce heating and cooling costs as well as fossil fuel consumption, slowing the carbon emissions that are disrupting the global climate. As previously stated, windows can be an expensive feature of a home, accounting for significant heat loss in cold weather and heat gain in warm weather. Single-pane windows, found in nearly half of all American homes, are the most inefficient energy consumption. Heat is lost through windows in four distinct ways:

  • Air leaks in and out of gaps along the edges (infiltration).
  • Heat is conducted through the window glass (conduction).
  • Heat energy flows from a warm object to any nearby cooler object until equilibrium (radiation). This can account for up to 65 percent of your home’s heat loss.
  • And as heat rises and cool air sinks due to their relative densities, the cold air at the inside surface of an icy windowpane flows toward the floor, sucking more air behind it toward the window (convection). This movement eventually causes the temperature in the room to fall. This is why it is critical to cut off airflow near the window.

Effective window insulation prevents heat loss while also assisting in regulating the surface temperature of the interior glass. Insulated windows help ensure an even temperature throughout the home’s interior by avoiding significant heat loss through leakage or convective airflow, increasing energy efficiency. 

They also allow heated homes to maintain a higher humidity level, resulting in better air quality and a lower risk of condensation on the windows.

How to insulate windows for winter

Get your windows ready: Before you begin, make sure your window, frame, and sill are all clean. Clean and remove any grime or dust with a damp cloth, and then clean your glass surface with a soapy sponge or squeegee. Once everything is clean, thoroughly dry it with a cloth or paper towels.

Window film insulation: Window film insulation is essentially a large sheet of shrink-wrapped plastic with some double-sided adhesive tape applied to it. This acts as a fence between the cool air outside and the pane, helping to keep the heat in. To begin, measure and cut the sheet to fit the dimensions of your window frame. Stick the double-sided adhesive to the outside of your windowpane. To improve the seal quality, shrink the film using heat from a hairdryer.

Window caulking: A high-performance sealant, such as calking, is a popular and cost-effective method for preventing winter draughts. To start with, use a putty knife to remove all of the loose caulking around the window frame. Then, insert sealant strips along with the interior wall frame or fill gaps or cracks with a caulk gun. This will stop cold air from entering the house through the interior sill and wall. However, in an emergency, it is not recommended to seal around a window opening.

Window insulation foam: Another quick way to insulate around windows is with expanding foam spray, which should be applied with a foam shooter gun. To begin, place a small drop in the corner of your window sill to show how much it will expand once applied. Then, apply a small bead of foam around your frame to create an air seal. If you don’t wish to use a foam spray, you can use foam rubber weather sealing strips that you stick around your window.

Window thermal treatments: Thermal curtains, blinds, or heavy drapes can help keep draughts at bay. These reduce radiant heat loss and trap more air within the fabric folds. Heavy curtains may not be the cheapest way to seal windows, but they look far more appealing.

Draft stopper or ‘snake’: Using a draught stopper or draft snake is one of the less-complicated options. It is simply a stuffed foam and fabric tube that should be placed horizontally along the bottom of your window. This will keep any draughts from coming from underneath; however, it won’t be an ideal solution in case of a breeze leaking from the sides or top of your window. Draft stoppers can be purchased at any home improvement store, or they can be easily made at home using a long sock stuffed with sand, beans, or even rice!

Also See: Winter Home Maintenance Tips | Tips for Removing Rust From Outdoor Metal Furniture | Choosing the Best Paint for a Steel Door


You can significantly control and limit the use of money caused by draughty windows by investing a small amount of time, effort, and money. Your apartment serves as your primary residence. Make certain that the money you spend each month on heating and cooling is not squandered.

Frequently Asked Questions 

What is the most cost-effective way to insulate a window?

Bubble wrap is often less expensive than window insulation film. Choose bubble wrap with large bubbles because it insulates better than bubble wrap with smaller bubbles. You can trim the bubble wrap to slightly overlap the window seams. When applying it to the window, make sure the bubble-side faces the glass.

Can bubble wrap be used to insulate windows?

If the bubble wrap does not adhere to your window on its own, you may need to use double-sided tape to secure it. Although bubble wrap will obscure the view out the window, it should allow light to pass through without difficulty.

Is it necessary to insulate your windows during the winter?

In the winter, window insulation can make or break your budget. Insulate your windows to save money this winter. All windows are the primary source of heat loss in a home in the winter, regardless of age.

Written by

Rostislav Shetman is the founder of 9Kilo Moving. He has been in the moving and relocation industry for more than 25 years, making him an expert in his field. Rostislav started as a helper, dispatcher and driver and has worked his way up to owning his own company. He takes great pride in his work and enjoys helping people relocate across the United States of America. When he's not working, Rostislav enjoys spending time with his family and friends. They are the light of his life and bring him happiness every day.