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In this article I'll share how to insulate RV windows to prepare for cold weather without blocking the sunlight. I'll go over several methods I tried or came up with myself as well as some other ideas for RV window insulation I've tested or read about. (To read about other ways we prepare our RV for winter, click here.)
How Improving Your RV Window Insulation Can Benefit You
One of the biggest causes of heat loss for RV owners who camp or live in an RV year round in cold winter climates is single-pane windows.
Additionally, if the RV is humid inside, condensation can form on the cold window surface, leading to mold or mildew problems. But even if a dehumidifier has lowered the humidity level inside the RV and you've solved your condensation problems, if the windows are still cold, that means expensive heat is escaping through them, causing the RV to feel drafty and the heating bill to skyrocket.
Here's a little anecdote to illustrate how much heat is lost through the windows of our fifth wheel: this year I was a bit lazy about getting the windows done, and one day recently I was sitting on the couch and felt a bit chilly. It was around 32 degrees Fahrenheit outside, but the thermometer/hygrometer on our fridge read 75. I moved the thermometer to the shelf I built behind my sofa next to the window, and half an hour later thermometer read 66. At that point I knew I'd better get a move on with my window project!
Methods for Insulating RV Windows
Hang Heavy Curtains
Covering your windows with thick, insulated curtains can make a big difference in helping to retain heat. You can open them during the day to allow the warm sunshine to come through the glass.
Covering the Windows with Reflectix
A lot of people cover their RV windows with Reflectix, but as sunshine is extremely important to my mood, especially during winter, anything that would block light wasn't going to be an option for me.
Additionally, while Reflectix may help insulate, it also repels an effective free source of heat: sunlight! Some RVers put Reflectix in their windows at night and take it out during the day to let the sun warm the RV via the greenhouse effect, but personally I prefer an option that keeps my heat from escaping through my windows during the day as well (and also doesn't require me to have to bother with it every day), since sitting next to a single-pane window on a cold day can feel rather chilly.
Clear, Heat-Activated Window Film
The first year I spent winter in an RV, I decided to use shrink plastic, which I had used in homes before. If you've never used it before, basically you put double-sided tape (included in the kit) all the way around the window frame, then cover the window with plastic stuck to the tape, and then you blow a hair dryer on it and the plastic shrinks and all of the wrinkles smooth out and the seal around the edges traps a layer of air between the plastic and the glass.
Important: the layer of air between the glass and the window covering is actually what provides insulation against the cold.
I've seen some RVers ask whether they should put the plastic on the inside or the outside of the window. If you put it on the outside, the only barrier you're adding between you and the cold is a thin layer of plastic. By trapping a layer of air between the plastic and the glass, this air is warmed by the sun during the day and takes longer to cool at night since the air has nowhere to escape to.
Still not convinced? Tape a piece of plastic over one of your windows on the outside. Wait a few hours, then put your hand against the glass from the inside and compare it to the temperature of an uncovered window. An insulated window shouldn't feel cold to the touch, and if it does, the insulation isn't working effectively.
I find plastic window insulation to be quite effective. In fact, I ended up leaving the shrink plastic on my hall windows all year since I always leave the shades in the hall down anyway to try to keep the sun from beating directly in on my hall thermostat. (Additionally, I added reflective window film to my hall windows to help with that problem.)
In spite of my love for shrink plastic, though, it does have a few problems:
- Some RV owners have trouble getting the tape to stay stuck to the window frame due to condensation and have to use a sturdier type of tape. We did not have that problem, however.
- Applying shrink plastic to all of the windows in an RV is a tedious, time-consuming task. It sucks to have to do it each winter.
- Our cat inevitably ends up tearing holes in the plastic with his claws, and by the end of the winter my window is covered with clear tape patches.
Motorhome Windshield Insulation
Most Class A RV's come with curtains that can be closed at night for privacy. These can be replaced with heavier fabric to help reduce heat loss as well. During the day, you'll want to open the curtains to allow the sun to come in and heat your RV via the greenhouse effect.
If you have a Class C RV, I think this insulated windshield cover seems like a great way to prevent heat from escaping through the front windshield at night. I haven't found a product like this for Class A's (that provides insulation instead of just blocking light), but if you know of one please leave a comment to let me know.
Insulating RV Windows with Bubble Wrap
After covering a few of the windows with shrink plastic last year, I became impatient with the process and decided to try another method for insulating windows against the cold: bubble wrap.
To cover a window with bubble wrap, all you have to do is dampen the glass and stick the bubble wrap to the glass with the bubble side facing the glass. A spray bottle or a damp rag works well for moistening the window, and if you add a little dish soap it will stick even better. Usually this is all it takes to keep the bubble wrap up all winter, but if it comes down you can simply dampen the glass again and stick it back up. I also used Scotch tape in a few places to tape two pieces of bubble wrap together.
Here's how I bubble wrapped the windows in my fifth wheel:
The bubble wrap method is very easy, but not very classy looking (IMO), and you can't see out a bubble wrap covered window, so I ended up only using bubble wrap on a few of my windows that I didn't mind leaving covered with the sheer shades all winter, like on the side of our house that faces our neighbors' front yard. One of those windows, the one behind my husband's desk, is actually still covered with bubble wrap that I never took down over the summer.
Also, I didn't find the bubble wrapped windows to be quite as well protected against cold as the shrink plastic windows due to the bubble wrap having perforated spots with no bubbles. So I don't plan to do bubble wrap again this year. (Update: I ended up using it on these windows again for the same reason I used it the first time – laziness!)
Velcro Window Covers Made from Clear Vinyl
I did use one more window covering method last year, just for a few of my screen windows, and that was to make clear vinyl covers attached with Velcro. I did this so that I could remove the covers and open the windows on nice days.
This method worked pretty well, and since the vinyl was sturdy, my cat didn't tear it up. There are a couple of drawbacks:
- The vinyl I used (heavy clear shower curtain liners) had creases in it that made it not look very good. If you buy clear vinyl on a roll at a fabric store, this wouldn't be an issue.
- The Velcro doesn't make an airtight seal, so it might not be ideal for extreme northern climates (but it's fine for us in Kansas City).
Even with those drawbacks, I decided to reuse this technique the windows that I might want to open. I'll share some pictures of those window covers later in this post.
Combining Window Insulation Techniques
My strategy for covering my windows this year is as follows:
- Shrink film on the hall window (leftover from last year)
- Bubble wrap on the window behind my husband's desk (leftover from last year)
- Plexiglass on my big windows.
- Vinyl covers attached with Velcro on my screens and smaller windows.
And now for a little more detail….
Making DIY Plexiglass Storm Windows
I would just cover all my windows with plexiglass if I could afford it, but it's kind of expensive (for me), so I decided to use it on three of my four big windows (the fourth being the bubble wrap window). I purchased three 24″x48″ sheets from Lowe's at about $30 apiece, and I had it cut at the store, but, as you will see, I ended up having to cut it myself also.
My Process
After unscrewing and removing my window shades and curtains and cleaning my windows with a microfiber rag wet with water, followed by a dry microfiber rag (which beats Windex at streak free glass cleaning, by the way), I held up the plexiglass to the window I planned to cover…and immediately realized I had forgotten to take into account the curved corners of the window.
After watching a few YouTube videos, I learned how to cut plexiglass using a utility knife (razor blade). You can actually buy a tool designed especially for cutting plexiglass, but I didn't really want to make another trip back to Lowe's, so I decided to try the razor blade method, and it worked just fine for my purposes.
Cutting the Plexiglass
First I used a Sharpie to mark where I needed to cut. Then I scored the mark several times with the utility knife over an old cutting board.
And finally, I grasped the corner with a pair of needle-nosed pliers and easily broke it off.
I then sanded the broken edge so it wouldn't be so sharp.
To adhere the plexiglass to the window frame, I used my favorite invention ever, clear acrylic mounting tape. This stuff is super strong, yet very easy to remove if needed. It also works when it's wet, as I learned when I used it for a project in my shower, so it should work even for people who have a window condensation problem.
Update: after using it for a project on the outside of my RV, I learned that acrylic mounting tape also works in sub-zero temperatures, as long as you heat it slightly (I used the palm of my hand) while applying it. I wrote an entire blog post about all the ways I've used this double-sided tape.
Unfortunately the plexiglass didn't come in a size that was tall enough for my window, so I ended up with about a two inch gap at the top. I covered this gap with a strip of clear shower curtain vinyl adhered with the mounting tape.
It doesn't matter, though, because that part is always covered with my pull-down shades.
Here is how the plexiglass storm window looks on one of my other windows:
The emergency exit latches protruded out too far for the plexiglass to cover on this window, so I used a strip of clear vinyl along the bottom the same as I did at the top of the other window. It should be very quick and easy to remove in case of an emergency.
I really love how the plexiglass storm windows turned out. They look like they came that way. I will may get plexiglass for a few more windows next year.
Difference With and Without the Plexiglass Storm Windows
Update 12/5/2018: This year I took a picture of one of my windows covered with plexiglass next to one that I had uncovered for summer and haven't gotten around to re-insulating yet. Look at the difference it makes! You can clearly see that the window on the left is cold because it's covered in condensation (meaning our expensive heat is escaping through it!), but the plexiglass isn't cold enough to cause condensation to form, meaning the air between the window and plexiglass is still warm and acting as an insulative barrier to slow down the loss of heat! Definitely a success I'd say!
Video of my Plexiglass RV Storm Windows
I did a little video follow-up about my plexiglass windows where you can see a little more detail:
Velcro Vinyl Window Covers
I made clear vinyl covers adhered with Velcro for the screen parts of the windows I covered with plexiglass so I could remove the covers and open the windows to let in fresh air on nice days.
Last year I made two vinyl window coverings, but only one was able to be reused this year because I didn't do a very good job of storing them and the Velcro came unglued and made a sticky cat hair magnet.
I actually decided to go ahead and use the one above since it was going to be mostly obscured by plants anyway. Then I made new ones, too.
My Process for Making Velcro Window Covers
To make the covers, first I cut 1″ Velcro with scissors so that it was 1/2″ wide and stuck it (both the hook part and the loop part together) to the window frames.
Then I cut a piece of vinyl a little bigger than the space I needed to cover and stuck it carefully to the Velcro, stretched as taut as possible to avoid creases along the Velcro.
Finally I trimmed the edges with a utility knife.
For this smaller window, I decided to cut the vinyl big enough to cover the entire frame, because on my windows where only the inner frame is covered the outer frame still gets pretty cold. It doesn't look pretty, but the shades and curtains hide most of it.
After I made these, I found out that there's actually a similar product for sale on Amazon. I haven't tried it yet myself, but here it is if you'd like to check it out:
So that's how I made RV window insulation to prepare my RV for cold weather. Please leave a comment if you have any questions! And if you would like to see the rest of the things we do to prepare our camper for winter, you can read about it in this blog post.
Should You Insulate the Outside of RV Windows?
If you live in an extremely cold climate, in addition to insulating your windows from the inside, you could also cover them with plastic from the outside. The main benefit to this I see would be to further seal the windows from drafts, as there would be very little if any space between the plastic and the glass to trap the air needed to create insulation.
Most RV owners who do this cover their windows on the outside with clear vinyl, plastic, or plexiglass taped on with foil HVAC tape, which can be used at any temperature and comes off cleanly when removed. I think clear vinyl would work best for this purpose, since it's sturdier and wouldn't be likely to tear in the wind. Bubble wrap could also work as long as there were no perforations to allow moisture and air to enter, and this would add another layer of insulation.
Just be aware if you do this that some RV windows have “weep holes” in the sill to allow condensation to drain, so you may want to leave the bottom unsealed. Here's a picture of what I'm talking about; I wasn't aware that these existed until recently!
Here's a picture of an RV with plastic covering the exterior of the windows from an RV owner named Deenise Thorsen (along side another image showing how she can still easily see out of the window).
Insulating RV Skylights
I really enjoy having a skylight in my RV shower because the sunshine helps me wake up in the morning, and the natural daylight lets me keep a few plants in my bathroom, but during the winter the skylight is one more place for heat to escape.
Recently I found out about a product that AirSkirts, a company that sells inflatable RV skirting, designed to solve this problem. It's an inflatable skylight insulator that sticks to the glass with suction cups and is made from clear vinyl that lets sunlight through. During the day, the sun warms the air inside, and this provides a buffer between the cold air outside and the warm air in your RV.
You can read more about the AirLight Skylight Insulator on the AirSkirts website.
Updates & Final Thoughts
Update 12/6/17: I still have one window that I haven't insulated yet because I open it to let my cat in and out of our camper, and the other night after boiling some water on the stove I noticed it was covered with condensation while all our insulated windows were completely dry! We don't typically have a problem with humidity (whether because of our climate or our RV design I don't know), but the boiling water had raised the humidity in the house, and evidently the single pane window was cold enough to cause condensation to form, while the other windows were not!
Update 1/4/17: We have had some really cold weather this past couple of weeks–colder than what's normal for Kansas City, with lows below zero and highs in the single digits, so I have been able to really see which types of window coverings are the most effective. Here are my conclusions:
- The plexiglass is definitely the best. It looks great, and the windows are noticeably warmer.
- I ended up using bubble wrap on the other two windows to the left and right of my husband's desk because I was too lazy to do more plastic, and it is actually more effective than I remembered. But, you can't see through it, so I still don't like it as a solution for all my windows (although it's better, in my opinion, than Reflectix, since it does let light through).
- The shrink plastic isn't a bad solution, but it's a lot of work and not as effective as plexiglass.
- The vinyl covers are the least effective, I think because the Velcro doesn't create a seal. They are still a lot better than nothing, but you can see in this photo below that quite a bit of frost still formed on the part of the window that was covered with vinyl (the part with the screen), while the part covered with Plexiglass (without a screen) hardly has any frost at all:
One RV owner suggested using magnetic strips instead of Velcro to create a better seal; if anybody tries that, let me know how it goes.
Click here to read about the other ways we prepare our RV for winter!
For more winter RV tips, check out my Winter RVing Resource Page!
Ashley Mann lives in a 38-foot, 5th-wheel RV with her husband and their cat, Professor Theodore. She enjoys the challenge of finding the perfect way to organize a space, and she loves seeing all the creative and clever ways people come up with to customize their RVs.
Well worth a read. Got great insights and information from your blog. Thanks.
Thanks for this helpful article! What is the thickness of the plexiglass that you use?
To be honest, I can’t remember…it was just the one that was cheapest at Lowe’s. The thickness of the glass doesn’t make much difference, as the insulation comes from the layer of trapped air.
Is it worth it to buy dehumidifiers
If you have a condensation problem, absolutely! We’ve never struggled with condensation in our RV so I’ve never purchased one; therefore I’d wait and make sure you have a problem first.
Hello what if are not using the trailer in the winter should you do this method..while storing it ..Thank you
Hi Edith, the main point of insulating the windows is to help the RV stay warm while you’re using it in cold winter, to cut down on heating costs and to make it more comfortable. There’s no need for this if your RV is in storage during cold weather.
have a nice day
Hi, I believe this person basically plagiarized your article. I was reading his thinking it sounded awfully familiar then realized he basically copied everything from you verbatim…
rvblogger . com/blog/rv-window-insulation/#comment-2228
Thank you for letting me know!
Hi, does the plexiglass work as well in the summer to help keep it cool? I’ve just started full timing and would like to do something that works for both cold and heat. I’m in Texas so we never really know what out seasons will look like.
Thanks
Sabrina
The plexiglass doesn’t really make much of a difference in keeping the RV cool because the layer of air trapped between the two layers of glass is no cooler than the outside air (and actually, it’s hotter) and since heat transfers to cold, not the other way around, RV’s heat up from heat getting in, not from cold escaping. The best way to keep an RV cool in summer is to reduce the effects of the sunlight beating down on it as much as possible, which can be done in various ways which I discuss in my article about how to keep an RV cool in summer. 🙂
My problem is not just cold but also heat from the entire slide out. I need a solution to this. Adding reflectix doesn’t really help when applied directly to the wall. There must be some air space and that makes it such a big project. Also the window problem. Wouldn’t the film that is suppose to act as an additional solar barrier work best? What about solar screen on the window screens. Looking for more options..
You’re right that Reflectix applied to an interior wall wouldn’t do anything except hold in the heat, and these clear window coverings wouldn’t do much to block sunlight either. Reflectix can be useful to cover a window to reflect the sun rays back out. As much I hate covering windows, when we were in Texas I used to slide a sheet of Reflectix behind the shade in one of the windows of our RV that the sun beat in during the hottest part of the day. I actually have a whole article about ideas for cooling down the RV that might have some other ideas that would work for you; you can check it out here.
Do you put the plexiglass on inside window frame leaving a space between the 2 or on the window itself. Are you able to open window with it on frame?
The plexiglass was attached to the inside of the frame with space between it and the glass which creates the insulating effect. I only put the plexiglass over the large window panes that didn’t open. For the part of the window that opened, I stuffed bubble wrap between the screen and the glass and/or covered the screen with clear vinyl.