How to Insulate Your Windows to Keep Heat Out

Do you have old, drafty windows that leak cold air out of your home in summer (or into your home in winter)? This is a huge problem that affects many homeowners. Not only does it ruin the comfort of your home year-round, but it also increases your energy bills by making your heater and air conditioning system work overtime!

Luckily, there are plenty of ways to insulate windows to keep heat out. They range from cheap DIY projects to heavy-duty home improvement jobs that require professional help. Keep reading, and we’ll walk you through all the different fixes so you can insulate your windows ASAP.

4 DIY window insulation solutions

DIY window insulation usually isn’t as effective as hiring professionals to fix or replace your windows. However, it’s much more affordable, and it can be quicker since professional window technicians are sometimes booked out several weeks in advance.

At the very least, these DIY solutions can staunch any window leaks until professionals arrive – and you may need to use a few of them at once to prevent hot air from getting into your home. 

Add window insulation film

Many homeowners use DIY window insulation kits to make their windows more airtight and prevent heat loss. The application process differs from kit to kit. Thankfully, it usually follows the same basic process: place a membrane of clear plastic film over the entire window – including the frame – then warm it using a hair dryer so it sticks to the window like shrink wrap.

This is fairly effective since it makes an airtight seal around your window, and because the film is transparent, it allows you to see through the window. There is one downside to this option, though: you can’t open the window. If you do, the film will break.

On the plus side, though, this method is affordable. Many kits cost less than $15 on Amazon, and some people make this method even cheaper by crafting their own kits out of tape and bubble wrap. However, bubble wrap will make seeing out of your window difficult.

Replace your windows’ caulking

For less obstructive insulation, consider applying a new layer of silicone caulk to your window’s frame. If you don’t already have a tube of caulk and a caulk gun, insulating your windows this way will probably cost you $30 to $40. Unlike the first method, though, it will allow you to open and close your windows at will.

Here’s how to do it. First, remove any old, loose caulk you see around the window frame. You may be able to pull it up with your fingers, though you might need to use a paint knife. Once the old caulk is removed, use your caulk gun to refill the cracks. When the new caulk is dry, it should keep warm air from leaking through your window. 

Remember that you may need to apply new caulking to the exterior of your window and the interior to create a truly airtight seal that can beat the summer heat. 

Install weather stripping

Weather stripping tape for windows is typically made from rubber or foam and always features adhesive on one side. To make your windows more airtight using weather stripping, open the window and stick a pre-cut strip to the top and bottom of each sash. Each strip will seal the window sash and the frame when the window is closed.

A roll of foam or rubber weather stripping usually costs between $10 and $30 depending on quality, though you may need multiple rolls if you’re treating several windows at once. Additionally, the adhesive on weather strips only lasts a year or two if you open and close your windows often, so you may need to replace the strips when necessary.

While using weather strips to insulate your windows means you’ll still be able to open and close them, it can make them a little more challenging to slide completely into place. If you notice that your windows can no longer close all the way or lock once you’ve added stripping, you may need to replace the strips you used with thinner or more pliable ones. 

Get (or make) a draft snake

The final way to prevent your home’s cool air from escaping without hiring professionals is to get a draft snake for each window. Draft snakes are long, closed tubes typically made from fabric and filled with cotton, sand, or foam. They’re designed to rest along a window sill – pressed directly against the window – to prevent airflow through the bottom sash. 

Draft snakes often cost between $12 and $50 depending on design and material, but if you have a sewing machine, you can make your own much more affordably. Simply create a tube out of old fabric, fill it with batting, sew it shut, and voila! You’ve got yourself a draft snake.

Professional window insulation solutions

If you’ve got serious window drafts and want to stop them up correctly, hire professionals to replace your windows or upgrade their treatments. 

Replace your windows with energy-efficient models

The best way to completely eliminate window drafts is to swap your old windows with high-efficiency replacements. Not only do energy-efficient windows with double-pane or triple-pane glass prevent drafts, but they can also mitigate solar heat gain and prevent harmful UV rays from filtering into your home, thereby keeping your home temperate in multiple ways.

Of course, these types of windows aren’t cheap. Costs vary depending on window quality and the number of window panes you get, but the average price of high-quality window replacement ranges from $750 to $1,400 per window. Remember, you could pay more to get state-of-the-art windows, though. 

The good news is that new windows can last for decades if properly cared for, and high-efficiency windows will reduce energy costs during their lifespans. This means that shelling out for nice windows now can net you some savings in the long run.  

Install thick window treatments

For an affordable alternative to replacing your windows, you could install insulating window coverings like blinds or curtains over them instead. Depending on your taste, these could be thick blackout curtains, insulating shutters, or cellular shades. Any of these options can significantly increase a window’s efficiency, though usually not as much as replacing the window itself. 

The exact costs for this installation method will vary drastically depending on what treatments you get, but you should expect to pay between $50 to $200 per window. 

Put storm windows over your existing windows

Your last option is to install storm windows over the exteriors of your drafty windows. Storm windows are thick, removable windows designed to protect a home during intense storms. They can also increase an existing window’s insulation by adding an extra barrier between your home and the air outside.

On average, installing a single storm window costs between $100 and $1,000, though prices vary depending on location and installer.

What are the benefits of insulating your windows?

One of the big reasons to insulate your windows is to save money. According to the U.S. Department of Energy, as much as 30% of residential heating and cooling energy usage is caused by poorly insulated windows. So for every $100 you spend to run your heater or air conditioner, you may be losing up to $30 of it to leaky windows. 

This means that insulating or replacing old, drafty windows could save you significantly more money over the course of several years than it initially costs.

Poor window insulation can cause more problems than just expensive drafts, though. For one thing, windows that leak air sometimes also leak rainwater that can damage your walls, drapes, and flooring. For another thing, leaky windows allow outside noise to filter into your home and disturb your peace and quiet. 

Insulating your windows for greater efficiency

Whether you batten down the hatches using one of our DIY methods or you hire a professional window technician to do it for you, you won’t regret it. You’ll likely notice a difference in your home’s comfort level right away, and you’ll certainly notice the difference when you get your next month’s utility bills.