When it comes to climate control in our homes, the largest point of heat transfer is at our windows. In the summer, the cooler interior absorbs heat from the outside, in the winter, it is the opposite. There are several solutions you can use to help minimize this heat transfer, though.
The best window insulation kits are designed to be easy to install and help minimize heat loss or excessive heat absorption. We will cover the various features of these kits and identify which one is perfect for you.
Benefits of Window Insulation Kits
Window insulation kits have a lot of benefits. When installed properly, they can do a lot for your home, yourself, and your energy bills.
Better energy savings.
One of the most significant benefits is using your heater and air conditioners less, resulting in a lower energy bill.
You will find that your home stays a more comfortable temperature year-round.
Window insulation is among the least expensive and easiest to install options available as far as energy savings go.
When it comes to out of pocket expenses, window insulation kits are cheaper than heavy curtains or replacing/upgrading your windows to higher efficiency models.
Window Insulation Compared
*Approximate coverage of an entire home (6-10 windows)
3 Key Questions Before Insulating a Window
1. What type of window am I insulating?
There are many different types of windows. From double pane and basement or garage windows to crank-open, each one poses different insulation problems. You may need to worry about the way the window opens, or how many panes there are.
You need to note if there are locks on the windows, where the screens are, how everything latches. All of these aspects, based on your window type, will play a huge part in the insulation you purchase.
2. What is the window’s U-Value?
To categorize windows for energy efficiency, the US Department of Energy uses what is known as a U-Value (also known as a U-Factor). This is a decimal number that shows how much heat, or energy, is lost through the window pane. Most energy efficient windows rate between 0.2 and 1.2, with lower numbers being better at insulating heat loss.
You may also see a rating labeled SHGC (Solar Heat Gain Coefficient). This is a number that represents how much heat from the sun comes inside the window. Since insulation generally protects from the inside, the U-Factor is a more valuable number to you when picking an insulation.
3. Which season are you insulating for?
We need to keep our homes cool in the summer months and warm in the winter months. Many insulation brands are one-way protectors, meaning they will work best for either summer or winter. In some instances, you can find insulation that works both directions.
For this reason, it is important to note which season you need to insulate for. Finding the suitable insulation for the right season (or direction of heat retention) will be a key factor in your final purchasing decision.
7 Best Window Insulation Kits Reviewed
Below are the 7 best window insulation kits, reviewed, compared and present to you. Read through each one and find out the best brand and type for your specific window types and needs.
1. 3M 2141W-6
Our #1 Window Insulation Kit
|No. of Windows||5|
|Sizes Available||1 roll, 10 yards|
|Installation Type||Over window with adhesive strips|
The 3M plastic sheeting window kit is one of the best options on the market. You get plenty of adhesive strips, a lot of plastic, and a simple install. There are 10 yards of sheeting in total, which is enough to cover five windows (3x5ft). As a cost-effective solution, it doesn’t get much better.
When installing, there is an extra step that a lot of window kits do not have. In this case, the use of a hairdryer shrinks the plastic to pull it tight, keep it clear and seal any gaps you may have created.
Once cut to size, you need to clean the window frame and mount the adhesive. After a few minutes to set, the adhesive will be semi-permanent and won’t move while you are installing the sheeting.
This type of window insulation is best for the winter months. It offers no tinting and doesn’t do anything to prevent heat or sunlight from entering the window. However, it can stop drafts and prevents condensation to some degree, so even in the summer you won’t have airflow leakage.
Aside from the crystal clear finished product, the sheeting also works to prevent frost build-up. This leads to melting and condensation, which, in turn, leads to mold or mildew. For a quick install and simple winter solution, there isn’t much better in this price range.
- Simple install
- Prevents condensation and frost
- Crystal clear sheeting
- Pulls tight to seal air gaps
- Not ideal for summer use
2. Duck MAX 284351 Heavy Duty Insulating Film
Best Insulating Film For Windows
|No. of Windows||Up to 15 windows|
|Sizes Available||1XL, 3, 15-window|
|Installation Type||Over window with adhesive strips|
Duck Max window insulation kit offers you 4 sizes to get the right fit for your project. The XL sheeting is designed to cover a door while the other dimensions are for regular windows. They come in packs for 3 windows or sold as a 5-pack for up to 15 windows. This way, you can mix and match and not waste money on too much sheeting.
The installation is simple, and much like our top pick above, the extra use of a hairdryer will shrink fit the plastic to keep it taught and wrinkle-free. The main difference here is that Duck doesn’t use the 3M tape, of course. However, Duck’s tape is excellent adhesive but may not peel off as cleanly as 3M when you take it down.
Some reports do claim that paint peels and the adhesive breaks off. Most claim that it is a clean peel, so it depends a lot on where it is mounted and the type of paint around your windows.
The other significant difference is that Duck brand rates its sheeting for both summer and winter. The summer rate comes from the blocked drafts, heat retention (when used with insulated curtains), and gap sealing. It still shouldn’t be left up year-round, though, as condensation, mold, and odors can form over time.
- Multiple sizes for your project
- Easy installation
- Seals tight for summer or winter use
- Adhesive may not peel cleanly
- Doesn’t prevent condensation
3. Great Stuff Insulating Foam Sealant
Best Spray Foam Insulation For Windows
|No. of Windows||Entire home|
|Sizes Available||12 ounces|
|Installation Type||Spray foam|
Great Stuff, as its name implies, is a good alternative to plastic sheeting. This is a spray foam used around windows and doors to seal gaps, cracks, and drafts. Unlike sheet plastic kits, spray foam is a permanent solution.
This can holds 12 ounces of foam that expands after spraying. The expansion gets into the cracks and gaps to fill them. Then it hardens to create a permanent seal. Note, though, that it does expand up to an inch, so a little goes a long way.
Like a welder’s seam, this foam does take a little practice if you are looking for an aesthetic finish. It is best to use the included hose on the nozzle to place the foam directly where you need it and let it expand before adding more.
This foam is yellow but can be painted once fully dry. If you need a different color, your local hardware store may offer them, though generally, all spray foam is yellow. Once sprayed, you will have no more drafts, the cracks are filled, and depending on where you apply it, you can still use the window or door.
You want to take care not to seal your windows shut (unless that is your goal) and from getting the foam on the glass. It is difficult to remove and will leave a residue.
- Permanent gap-fill solution
- Prevents drafts
- Won’t hinder window operation
- Can be painted
- Can stain glass or wood
- Takes practice to use correctly
- Difficult to remove
4. Frost King V73/9H Indoor Shrink Window Kit
|No. of Windows||Up to 9 standard windows|
|Sizes Available||3-pack, 9-pack|
|Installation Type||Over window with adhesive strips|
The Frost King plastic is designed for use over the colder months of the year. If you have basement windows, older windows with drafts and gaps, or just want to have a more comfortable room, this is for you.
This biggest concern here is the tape adhesive used to attach the plastic to the windows. The adhesive works well when applied correctly, but it takes a great deal of time. Once the tape is applied to the clean mounting surface, you should press and hold it for at least 2 minutes. After this, it needs to set up for at least another 10 minutes without any form of contact.
Only after the tape sets can you remove the backing and apply the plastic. The next step is to use the hairdryer and shrink the plastic to fit. Once again, the tape becomes an issue. If it hasn’t had time to set to the plastic, it may slide, or the plastic can pull away.
However, if you are patient enough, your fit will be perfect and the seal even better. Air, gaps, heat, and drafts are sealed off, keeping the heat inside the room and preventing heat transfer loss.
This will need to be reapplied every season, even if you decide to leave it up, the tape will lose its hold and need to be remounted. Otherwise, the package comes with individual sheets for standard sized windows, so you won’t need to cut to fit.
- No cutting required
- Ideal for winter months
- Colder climates get better usage
- Tape is challenging to use
- Must be reapplied each season
5. SmartSHIELD Reflective Insulation Roll
Best Way To Insulate Windows For Summer
|No. of Windows||Up to entire home|
|Sizes Available||16- 24- 48X50, 48X100|
|Installation Type||Foam insulation roll with nails|
The SmartSHIELD aluminum foam solution prevents a lot of things besides just heat to pass through. The aluminum (or white option) reflects sunlight and withstands most elements. It will not condensate and also prevents bugs from passing through.
For a permanent solution, this foil-wrapped foam easily cuts to fit any window or door size. There are 16, 24, and 48-inch widths with rolls in both 50 and 100-feet. With just a couple of rolls, you can cover every window in your home.
Installation is best done with the included hardware (coated nails) to help seal better and prevent moisture build-up. You don’t need to shrink fit with a hairdryer, either. As long as you have the right width for your window, you can prevent virtually all heat from the outside entering your home.
With significant savings on your energy bill, the rolls will pay for themselves in the first season. However, because of the mounting style, if you do choose to remove the foam rolls during the winter months, you will need to purchase a new roll for the next summer application.
- Easy to install
- Works all summer long
- Water and bug resistant
- Can tear easily when removing
6. Duck Brand 286217 Window Shrink Film Insulator Kit
Best Window Insulation For Winter
|No. of Windows||Up to 5|
|Sizes Available||XL, 3, 5, and 10 window sizes|
|Installation Type||Over window with adhesive strips|
Duck is back with another type of plastic sheeting. This one is similar to the second pick on the list, except that it is thicker and comes in a single sheet of 210-feet (total when cut for 5 windows). This is enough to cut to fit up to 5 windows, a single door or multiple standard windows.
You can buy a larger kit for up to 10 windows, or a smaller package just for doorways. However, this 0.7mil plastic will keep the heat in and the cold out. By blocking window drafts, cracks, or gaps, you can actually use your heater less, as the warm air in the home is retained.
If you find that a window isn’t holding air or you have older frames that may not be air-tight anymore, this is the perfect solution for the winter months. Be warned, though, that the Duck tape shipped with this kit isn’t designed for unfinished wood.
If your window frames are not painted, you will need to purchase a different adhesive tape to use. It is also not designed to adhere well to drywall or plaster, so make sure you stick the window frame itself and not the wall surrounding it.
- Easy to apply
- Sets crystal clear
- Ideal for heat retention
- Tape isn’t the best for unfinished wood
- Needs to be replaced each winter
7. Reflectix BP24050 Bubble Pack Insulation
Best RV Window Insulation
|No. of Windows||Up to 15 RV sized windows|
|Sizes Available||2×50 feet|
|Installation Type||Bubble wrap with adhesive or nails|
Reflectix has a bubble wrap, aluminum insulation perfect for your boat or RV. The cut-to-size roll can easily fit an entire RV full of windows and have enough leftovers for next season. You will need to attach the insulation with double-sided tape (not included) or nails. However, the tape is advised since you will need to more easily remove the insulation when the RV is in use.
With over 50 feet in the roll (each roll is 24-inches wide), you can get the exact fit you need. It is advisable to clean the windows and the window frames before applying. You will also want to make sure everything is dry. Unlike aluminum foam, the air-bubble wrap doesn’t prevent condensation.
The heat is blocked on both sides, keeping the temperature inside the same, while the air pockets prevent heat transfer. With the shiny aluminum outer area, the sun is reflected and not absorbed. The inside stays cooler longer in the summer and warmer in the winter.
Installation is simple but needs to be replaced every season. You need to purchase a new roll for each season, too, as the foil does rip and tear easily. When you remove it, trying to go slow and preserve the foil is almost a waste. With the cost of new insulation rolls, it is easier to replace than reuse.
Plus, if you attempt to reuse the same insulation for several seasons, the material will degrade and not hold air leaks and heat as well.
- Ideal for small spaces
- Multiple interior uses
- Large rolls for multiple windows
- Must be replaced each season
- Adhesive not included
Affordable Ways of Insulating Windows
When it comes to insulating your windows, you aren’t without options. Some of the best methods, aside from replacement, are fairly inexpensive and work well through several seasons.
Window Film/Insulation Kits
Film kits are among the easiest to apply and longest lasting. When installed correctly, they lower the U-Factor of the window, reducing the amount of heat lost to the outside. They also prevent condensation between the layers, which reduces the chance of mold growth.
Foil bubble wrap insulation is an excellent solution for short-term options. The foil reflects solar heat, and the air bubbles inside help trap and prevent heat loss from the inside. They can cause condensation to build up, though. Left up for extended periods may result in mold or mildew growth around the window and sill.
Magnetic insulation is another short-term answer that can be applied to metal window frames with ease. You can insulate a room or an entire home in just a few minutes. However, like the bubble wrap, there will be gaps between the insulation and panes. This may lead to mold and mildew growth if left up for long periods.
Rope caulk is a pliable putty that you can use to stop drafts and fill gaps or holes around doors and windows. It isn’t advised to use on the glass itself or in the window jams. While it stays soft and pliable for a long time, once it sets and hardens, it is difficult to remove. This can lead to windows not able to open or prevent them from locking.
Spray foam is a more permanent solution for use around doors and windows where the air gaps are in the window itself and not in the glass panes. Overuse can cause fumes for a short time and may prevent the window from opening. However, when used correctly, it will seal any gaps, holes or air passages with ease.
Useful Tips When Installing Window Insulation Kits
Window insulation kits are a great way to prevent drafts and help lower the U-Factor of the window. However, there are a few things to keep in mind when using these kits.
- Ensure the area of the window or frame you will attach the film to is clean and dry. Rubbing alcohol is a great cleaning option here.
- Let the adhesive strips set for about 10 minutes after applying to the window frame. This increases their strength and prevents them from shifting when applying the film.
- Use bubble wrap inside the film to help retain heat in the home. The air pockets keep heat and prevent it from escaping through the window.
- If you attach to the window frame, don’t leave the film up all the time. You won’t have access to your windows, and condensation can form inside, leading to mold.
- If you attach to the windowpane, make sure to use a shrink or cling style film instead of an adhesive mounted version.
- For larger gaps or drafts, use spray foam to fill the gaps first.
- Rope caulk can help seal off drafts too, without the fear of having a messy looking window.
- Utilize rolling window shades, mini blinds, and heavy black-out style curtains to prevent heat loss further.
People Also Ask (FAQ)
How effective is plastic window insulation?
Window insulation kits are quite effective at reducing heat transfer and preventing drafts. Most insulation kits will not prevent condensation unless they are the type that mounts to the window pane itself. For this reason, plastic insulation kits are not recommended for using year-round. Any moisture between the window and the plastic can result in condensation and eventually mold or mildew.
What is the difference between window insulation kits and insulated curtains?
Insulated curtains are designed to keep the sun and heat out, or more accurately from passing through into the home. On the other hand, window insulation kits are designed to keep the heat in and prevent drafts. Curtains maintain airflow and don’t allow condensation to form, though, and window kits are considerably cheaper.
What window coverings are best for insulation?
If you want to use window coverings for your insulation, the best bet is to use a mixture of options. The best combination is to have rolling or mini-blinds along with insulated or black-out curtains. This will allow airflow, prevent condensation, and keep the cool or heat in without allowing drafts to become a nuisance while keeping the sun’s heat outside the window.
Should I put the plastic on the outside or inside of my windows?
Plastic from window insulation kits needs to be applied inside of your windows. The directional film is made for being used indoors and can easily tear, rip, or come off it mounted outside, exposed to the elements.
What is the best way to insulate old windows?
Old windows benefit most from blocking holes and sealing drafts. This is best done with either spray foam or rope caulk around the main window frame and sill. You should also use rope caulk around the windowpane frame to help block loose pane drafts. Window coverings such as blinds or insulated curtains will do the rest.
Do Duck window kits work?
Yes. Duck is a well-known and reliable brand for all of its products. Their window kits are among the top rated and best reviewed of all window kits on the market. If you choose to go with Duck and follow the installation instructions, you won’t have any issues.
Window insulation kits are a great way to help reduce energy costs, retain heat in the winter and cold in the summer. Reducing the amount of time your air conditioner or heater needs to run is always a benefit.
This article was designed to help you identify the best window insulation kits for your specific window types and needs. If you are still in doubt, take another look at our top pick, the 3M 2141W-6. It covers all the bases, is affordable, and easy to install.
Last Updated on July 16, 2021
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