Double-pane windows in RVs are great for helping to maintain a more comfortable temperature inside the rig. However, they are prone to seal failure, which can lead to fogging (the buildup of condensation between the panes of glass). While fogging won’t affect the window’s function, foggy windows can look bad and may prevent you from having a clear view out. It may also impact the resale value of the RV.
So, let’s take an in-depth look at how to repair fogged RV windows.
What Causes Foggy RV Windows?
Foggy RV windows are typically caused by window seals (not the ones that seal the window to the RV, but the ones between the two panes) that are no longer tight. A good seal between double-paned windows prevents condensation from forming inside. RV windows fog when that seal is compromised and outside (often moist) air is allowed in. This happens pretty commonly on RVs because the seals weaken over time and travel.
It’s crucial to repair foggy RV windows as soon as they appear, if possible. If left long enough, the moisture build-up between the panes can cause permanent etching of the glass. And, once the glass is etched, an easy DIY repair is no longer possible, and the window will likely need to be replaced (either the whole window or at least the damaged glass). Should you need to replace your RV window completely, you can follow the step-by-step instructions in our post on the topic (or watch this video) to do this as a DIY project:
How to Repair Fogged RV Windows
There are several approaches you can take to repair foggy RV windows. You can either tackle this piece of RV maintenance yourself as a DIY project, or you can send the window out for repair to an RV window repair specialist. Either way, you’ll need to remove the window (just watch the removal half of the video embedded above).
DIY RV Foggy Window Repair
If you decide to repair your fogged RV windows as a DIY project, there are a number of ways you can do this. In a nutshell, what you’ll need to do is the following:
- Remove the window from the side of the RV
- Remove the two window panes from the frame
- Separate the two panes of glass by completely breaking/cutting the seal that holds them together
- Clean the glass panes (removing the fog… if they were left too long, and etching has occurred, you may need to use a mild abrasive to re-polish the inside surface(s) to make the glass clear again)
- Reassemble and reseal the panes, making sure they’re well sealed and dried
- Allow time to cure
- Reinstall the glass in the frame
- Reinstall the window onto the RV
- Clean your (now de-fogged) window and enjoy the view!
NOTE: If you choose to buy a kit to complete this project, you’ll need to start by measuring the size of the window in order to know what kit to purchase. You’ll also need to check the space between the two panes of glass. This is usually a distance of 3/16”, but you need to buy a repair kit that has the same spacing. If you don’t, your window may not fit back in where it belongs.
You can purchase a kit from Foggy Window Repair Kits, or you can pick one up on Amazon:
- This seal is 3/16 inch thick and Ten Feet long
- This is a Do It Yourself product! On a skill level of 1 to 10, this is a 3 or 4. You'll get a QR Code to scan for the complete video on how to do this...
In addition to either of the above kits, you’ll need ⅛” thick x ⅜” wide closed-cell foam double-sided adhesive tape to use for sealing the window frame back to the side of the RV when re-installing the window:
- SIZE OF THIS FOAM TAPE - 3/8 inch Wide x 1/8 Thick x 75 ft Long. Our Foam Sponge Tape is easy to cut, flexible enough be customized into different...
- FOR PROFESSIONALS OR DIY's - High Performance Window Glazing Tape is designed to form a solid structured air barrier leaving no space for the air to...
You’ll also want to use one of the following products to seal around the top of the window frame after re-installing:
- USE: Paintable sealant helps seal perimeters of RV windows, entry doors, compartment doors, and joints
- COLOR: Clear material to let your RV surfaces shine through
- Flash Point: 93.0 Degrees_Celsius
- Excellent Adhesion To Many Surfaces, Even When Damp
Here’s a video that might be helpful to you as you consider repairing your RV foggy window repair:
Have You Repaired Fogged Windows On Your RV?
If you’ve completed this project in the past, let us know how it went and what was your chosen method of addressing your foggy windows.
Free RVing Tips, Tricks, Reviews & Giveaways
As 20-year full-timers, we share everything we’ve learned about RVing over the years. Join our online community to receive a wealth of great RVing knowledge delivered daily to your inbox.
Whether you’re a new RVer or a seasoned full-timer, you’ll love the wide range of RVing topics we cover. Don’t miss a single article or any of our famous Giveaways. Subscribe to our newsletter today!
Ian
Thursday 31st of July 2025
Great video, how about one on removing the window treatments ie. Valence and blinds.
Glen Thompson
Saturday 20th of July 2024
I would like to try this diy project on my entry door. 2006 Itasca Horizon, could I guess or assume that it’s 3/16th , not wanting to take it out first to find out? Also, not seeing access to screws from the inside of door, am I going to have to take the complete inside of door cover off to get to the screws ? I wished your video example would have done a entry door.. thank you
DDuke
Friday 4th of August 2023
Glad you brought up this subject! I noticed on my brand new Jayco Eagle 5th wheel huge condensation weep holes? It comes with frameless windows, but every window has a cut out of 3/4” for condensation to drain out? Now explains why I have condensation buildups on some of my lower windows. I guess I will have to purchase a matching foam and fill them all in. Just another issue with Jayco’s poor builds!
Patrick
Friday 5th of August 2022
Had to replace my driver's side window was NOT a DIY task. As this window was EXTRA LARGE and screws were hidden behind overhead storage compartment asking motorhome mfg.(newmar) for assistance got nowhere, they said to take it to a service center which we ended up doing.
Don
Friday 5th of August 2022
Did you mean to put expediently in your email announcement for the page. You might want to us expeditiously in it's place next time. Look 'em up.
TheRVgeeks
Friday 5th of August 2022
An editing oversight, which we didn't catch until it was too late since the email had already gone out.