How To Replace an RV Window, and How It's Made!

An RV is part house and part vehicle, and sometimes, after the “house” has been driven for miles and miles over bumpy roads, maintenance issues can arise. Among the potential repairs that an RV owner may face is an RV window replacement.

We faced this issue several years ago and met it head-on with our desire to DIO (Do It Ourselves) as many of our own RV maintenance and repair projects as possible. Because RV windows can crack, break, come loose or, as in our case, lose proper seal and fog over, today we’re bringing you our step-by-step guide to RV window replacement, showing you how to measure and install a new RV window.

For those of you who are more visual, you’ll appreciate our step-by-step tutorial video, above. If you’re partial to the written word, the steps are laid out below. Or enjoy both!

Tools for RV Window Replacement

These are the tools we needed for our RV window replacement. Depending on your RV, you may or may not need all of these tools for your project. Or you might need a few more.

How to Measure RV Windows for Replacement

We had our new window custom-made by Peninsula Glass in Vancouver, Washington. They regularly ship custom RV windows, but we were on-site and had a chance to observe how meticulously their technicians work to create their products. The replacement window they made for our rig is higher quality than the original by far.

Peninsula Glass can custom make almost any size or shape RV window to your specifications. No matter where you buy your new RV window, though, you’ll need to provide accurate measurements. Let’s break down our process for measuring an RV window for replacement.

Note that we’re measuring from INSIDE the RV.

Begin by removing any window valance, blinds, or shades.

Next, remove all screws around the perimeter of the window, and remove the inside frame.

NOTE: Once you’ve removed the inner window frame, be very careful… the outer portion of the window may not be held in by much if anything. Don’t put any outward pressure on the window while taking your measurements or it could come loose and fall. For extra safety, you may want to have a helper on a ladder outside, holding the window in place while you measure.

Removing the frame prior to RV window replacement.
Carefully remove the frame of your old window so that you can measure the opening (NOT the window itself).

Measuring the RV Window Opening

If you’re replacing an oddly shaped window, it’s best to check with the maker of your new RV window for the exact measurements they need. For our rectangular window, we needed to take only four measurements.

Please note that we’re measuring the opening itself – not the old window. Using a measuring tape, take careful note of the width and height of the opening. It’s a good idea to take measurements at several points so you have an idea of how cleanly the window opening was cut. If the measurements vary, be sure that the ones you provide the replacement RV window manufacturer will allow the new window to fit.

Measuring RV Sidewall Thickness

Next, measure the thickness of the wall (depth of the window), from the exterior wall surface to the interior wall surface.

For this measurement, use your ruler (with measurements that run all the way to the end). Insert the ruler into the wall until it touches the outside of the window frame.

Measuring the depth of the wall.
The thickness of the window is equivalent to the depth of the wall, which you’ll measure with a stiff ruler that has measurements all the way to the end.

How to Measure RV Window Corner Radius

Some RV windows have rounded corners like ours. Most have either a 2.5-inch or 3-inch radius, but it’s important to accurately measure this. Here are the steps we took to confirm this important measurement:

First, we printed out this Radius Measurement Template from the Motion Windows (Peninsula Glass) website. We used our ruler to confirm that the radius of the printed template was exactly 5 ½ inches, assuring us that the template had printed correctly (if yours doesn’t match, be sure to adjust your print settings and print a new copy until it measures exactly).

We then used our scissors to carefully cut around the edge of the printed shape, giving us our final template. Next, we placed the template against the curved window opening to confirm that our radius is 3 inches.

Using a template to measure the radius of the curve of the window prior to rv window replacement.
Measuring the radius of the curve of the window opening is accomplished using a template.

Now you may replace your window frame, window, valance, and shade or blinds. Yes… doing this job right does require removing some things twice. But it’s worth it, and good practice!

RV Window Measurement Mistakes to Avoid

Because accurate measurements are so important to this project, before we move on to the step of ordering the new window, let’s run through a few common measurement mistakes so that you’re sure to avoid these when measuring your RV windows.

Measuring the Window Instead of the Opening

Measurements of the old window and the window opening are often different. In fact, they can vary as much as half an inch on the sides, top, and bottom. Window manufacturers use filler strips to keep the window level and snug. This is why it’s so important to measure the opening and not the original window itself. Failing to do that could result in a replacement window that doesn’t fit correctly.

Not Double Checking Your Measurements

Measure twice, cut once, right?

Take your time to get an accurate measurement, and double-check it by measuring a second time.

Rounding Up or Down

Exact measurements are important to RV window replacement. We don’t want to loosely measure and round up or down. Always measure to the nearest 1/16th of an inch. Take a close look at your tape measure and be sure you know which are the 1/16th-inch measurements.

 Check your tape measure markings
This tape measure goes down to 1/32″ markings, so be sure you know which are the 1/16th inch marks.

Not Checking Manufacturers Website for Guides and Tips

The window manufacturers themselves are the best authorities on how to install their products. The manufacturer of your new RV window has likely included helpful guidelines or tips to make the installation easier. These types of instructions are often included on manufacturers’ websites as well.

If your new window came with instructions in the package, be sure to keep those handy as they may have detailed step-by-step directions in an included booklet.

Measure Twice, Buy Once

We know we’ve said this already, but it’s worth repeating that when taking measurements for RV window replacement, ALWAYS measure twice, confirming accurate measurements before ordering your replacement window.

Measuring accurately for the right fit will not only make installation a breeze but will also help to prevent the bane of every RVers existence – leaks!

Now let’s move on to ordering a new RV window.

How to Order Your New RV Window

The process may differ if you’re not ordering from Peninsula Glass, but we printed out this order form, entered our information and window measurements, and placed our order.

When your new RV window arrives, follow the steps below to install it:

How to Install Your Replacement RV Window

Remove the Old Window and Prepare the Area for the New Window

First, remove the inside frame of the window just as you did when you took your measurements, again being careful not to accidentally knock the outer part of the window loose from the opening.

There may be a bead of sealant around the top of your old window or between the outer window frame and the RV’s sidewall. If so, you’ll need to remove this prior to removing the old window.

Moving to the outside of the RV, use your plastic putty knife (yes PLASTIC, to avoid scratching your RV’s finish) to carefully break the seal around the old window and remove it. Pro Tip: Be sure to have your old window OPEN, so that you can hold onto it tightly until it comes loose from the seal.

Removing the old window prior to RV window replacement.
Be sure the window is OPEN so that you can firmly grasp the window as it falls out of the opening, once the seal is broken.

Scrape off any remaining sealant using your plastic putty knife, and clean off any remaining debris using mineral spirits. Give the area a final cleaning using rubbing alcohol to ensure that the area around the window opening is free of any oily residue.

On the new window, pry off the small adhesive strips that hold the ends of the inside frame together at the seams, and set the new frame aside for now. Take your new window outside and prepare to install it!

Dry Fit the New Window

With the new window open to ensure that you have a tight grip on it, set it into the opening, dry fitting it to check the alignment. If possible, have someone inside the RV take a close look, ensuring that there’s no extra space at the top of the frame.

Note: the window doesn’t have to fill the opening completely, and it’s perfectly normal for there to be some play in the window setting at this point.

If you do find that you’ve got a little extra space at the top of the window (which is totally normal), use a couple of small shims (rubber or wooden) set inside the bottom of the window sill to shore up the window and hold it as centered as possible in the opening. Dry fit the window again, to make sure that the spacing is now the same at the top and bottom of the window.

Install Your New RV Window

Begin by setting your new window on a flat surface covered with a soft cloth, with the outside of the window facing down. Clean all the way around the edge with rubbing alcohol and a clean cloth. This will ensure that the surface is clear of all residue.

Using the included roll of double-sided, closed-cell foam tape, apply the tape. Begin at the center of the bottom of the window, pressing it into place and removing the paper backing as you go. Pro Tip: Remove the paper backing of the tape just prior to rounding each corner for a perfect, flat, unbroken seal. When you reach the end, cut the tape to allow about ½ inch of the end of the tape to overlap the point where you started.

Overlapping the foam tape around the window to ensure a good seal.
Once you’ve brought the foam tape around to meet the beginning, overlap the end of the tape about 1/2 inch, ensuring a good seal.

Use your spray bottle to spray water all around the tape. It may seem strange to wet something you want to stick, but it will help you to place the window WITHOUT it sticking to the RV sidewall. Once the water evaporates, it will allow the frame of the window to adhere to the outer wall of the RV, providing a water-tight seal.

Spray water around the perimeter of the window opening on the outside of the RV as well.

Set the new window into the opening gently – don’t press the tape into place just yet. First, ensure that you have the same amount of space on all sides of the window. Having someone inside the RV can be very helpful with this.

Once the window is positioned correctly, push against the window frame from the outside, firmly adhering the foam tape to the RV.

Put the inside frame in place and install the screws, making sure to only use the screws that came with the new window, beginning at one of the seams where you removed the adhesive tape earlier in the installation process. See our video at the top of this post for explicit instructions on the best process for screwing in the new window frame correctly.

Wipe off any excess water, press the two drain covers into place at the bottom of the frame, and pop the screen into its track. If your RV’s manufacturer used sealant at the top of your windows as Newmar did with ours, we suggest replacing that sealant at this time using the Pro-Flex RV Sealant.

Finally, congratulate yourself on a job well done, and enjoy your brand new RV window along with a wonderful sense of accomplishment.


RV window replacement may seem daunting, but if you take your time and follow the steps outlined in this guide, this task becomes a doable DIY project.

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We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

We sometimes receive products for evaluation at no cost, and The RVgeeks are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites. But our opinions are our own, you won’t pay an extra penny, and we only link to products we personally use, love and can recommend to friends with complete confidence.
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