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How to insulate your windows for winter

Someone sealing base of window frame with strip
Someone sealing base of window frame with strip (Image credit: Shutterstock)

If you’re wondering where that draft is coming from inside your cozy home, your windows are probably to blame. Rather than spending a fortune on new windows (or sweaters!), you can easily insulate your chilly windows to keep the heat in for winter.  

What you’ll need

 

Damp cloth and towels

Putty knife

Caulk gun 

Window film

Expanding foam

Thermal window treatments

Draft ‘snake’ or stopper

In fact, sealing your windows for the winter is a cost-effective, no-fuss way to prevent cold air coming through any gaps or cracks. It also regulates the surface temperature of your window to ensure no condensation build-up, which would be the case for those who crank up their heating.

What’s more, knowing how to insulate your windows for winter will save you more money on heating bills, since you’ll no longer be losing heat. The good news is there are plenty of easy and budget-friendly ways to insulate your windows. 

How to insulate windows for winter

Prepare your windows — Before you start, make sure you have a clean window, frame and sill.

Use a damp cloth to clean and remove any grime or dust, and give
your glass surface a good clean with a soapy sponge or squeegee. Once all clean, dry thoroughly with a cloth or paper towels.

Cleaning window pane with cloth

Cleaning window pane with cloth (Image credit: Shutterstock)

Window film insulation— Window film is essentially a large sheet of shrink-wrap plastic with some double-sided adhesive tape. This acts as a barrier between the cool air outside and pane to help keep in the warmth. First, measure and trim down the sheet to fit the dimensions of your window frame. Stick to the outside of your window pane with the double-sided adhesive. Next up, shrink the film using heat from a hair dryer to improve the seal quality. 

Window caulking — High performance sealant like calking is a popular and cost-effective way for winter drafts. First, remove all of the loose caulking around the window frame with a putty knife. Then, either insert sealant strips along the interior wall frame or you use a caulk gun to fill any gaps or cracks. This will prevent cold air from coming through the interior sill and the wall. Though, it’s advisable not to seal around an opening of a window in the case of an emergency.

Caulk gun sealing window base

Caulk gun sealing window base (Image credit: Shutterstock)

Window insulation foam — Expanding foam spray is another quick way of insulating around windows, and should be applied using a foam shooter gun. First, apply a small drop in the corner of your window sill to indicate how much it will expand once applied. Then apply a small bead of foam to create an air seal around your frame. If you don't want to use a foam spray, you can always opt for foam rubber weather sealing strips that you just stick firmly around your window. 

Foam sealant strips on the window sill

Foam sealant strips on the window sill (Image credit: Shutterstock)

Window thermal treatments —Thermal curtains, blinds or heavy drapes can do well to keep out those annoying drafts. Not only do these reduce radiant heat loss but also trap more air within the folds of fabric. Heavy curtains may not necessarily be the cheaper option to sealing windows, but they look much more appealing.

Curtains on a window

Curtains on a window (Image credit: Shutterstock)

Draft stopper or ‘snake’— Perhaps one of the more fuss-free options is to use a draft stopper or draft ‘snake’. This is simply a stuffed foam and fabric tube to place horizontally along the base of your window. This will prevent any drafts coming from underneath, however, if you have a breeze coming from the sides or top of your window, this won’t be ideal. Draft stoppers can be bought from any homes store or you can easily make it at home using a long sock stuffed with sand, beans or even rice!

How often should I insulate my windows?

Generally, it's best to insulate your windows before the winter sets in. Depending on the quality of your caulking, this should be redone every five years. 

Cynthia Lawrence

Cynthia Lawrence specialises in Homes ecommerce, covering all things homes and garden-related. She has a wealth of editorial experience testing the latest, ‘must-have’ home appliances, writing buying guides and the handy ‘how to’ features. 


Her work has been published in various titles including, T3, Top Ten Reviews, Ideal Home, Real Homes, Livingetc. and House Beautiful, amongst many.


With a rather unhealthy obsession for all things homes and interiors, she also has an interior design blog for style inspiration and savvy storage solutions (get rid of that clutter!). When she’s not testing cool products, she’ll be searching online for more decor ideas to spruce up her family home or looking for a great bargain!