RV Window Seals Shrinking? Why and How to Fix It

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Have you noticed your RV window seals shrinking?

As the seals age, they may start to shrink for many different reasons, leading to leaky and drafty windows.

Fortunately, there are a few easy ways to fix this problem, two of which do not involve replacing the seal altogether.

In this post, we’ll discuss why RV window seals shrink and how to fix them with 3 easy methods.

Why Do Window Seals Shrink on an RV?

RV window seals shrink due to age, temperature, sunlight, improper installation, and just normal wear and tear.

These rubber seals often dry out over time or deteriorate due to temperature fluctuations and direct sunlight exposure, which may cause them to shrink. There are ways to help protect your seals from these elements, which we’ll get into below.

RV window seals and gaskets can also be jarred loose over time by wind, heavy rains, bumps in the road, etc.

If your RV is fairly new and you notice your RV window seals shrinking, it may be due to improper installation. Before attempting to fix the seal, check your vehicle’s warranty to see if it’s covered.

Whatever the cause, there are three main methods we can use to fix the shrinking seals and get your windows back to new again!

How to Fix the Seal on a Camper Window

Depending on the severity of the shrinkage and your skill level, we have three options to fix your window seals.

I recommend starting with method 1, as it fixes most seal shrinkage issues and is fairly easy to perform. If the shrinkage is severe, you may have to move on to method 2.

Important: If you don’t feel comfortable performing any of these methods, take your vehicle to a certified RV technician to have the seals replaced.

Method 1: Stretch the Seal

It’s very common for window seals to dry out and shrink. So, before replacing the entire seal with a new one, I recommend you:

  1. Remove the shrinking seal from the window.
  2. Apply a generous amount of 303 Protectant Spray to the seal.
  3. Massage the spray into the seal as you stretch it out.
  4. Replace the seal.

More often than not, this will fix your seal issue. And using 303 Protectant Spray will help give the seal new life, protect it from the elements, and keep it from shrinking again.

303 Marine & Recreation Aerospace Protectant

303 Marine & Recreation Aerospace Protectant

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Method 2: Apply Heat to Seal

Another method you can try is to apply heat to the dried-out, shrunken seal and stretch it back out.

Be careful not to apply too much heat to the seal as it could damage it.

Tip: If using the hairdryer method, it’s still a good idea to apply 303 Protectant Spray to the seal to help protect it from the elements and keep it from shrinking again.

Method 3: Replace the Rubber Seal on Your RV Window

If the seal under the window frame starts to shrink and deteriorate, we can simply replace it.

RV 101® - Resealing & Replacing RV Windows

Materials Needed:

Tip: In the video above, they use the Seal-Tite Foamcore Window Seal Repair Kit. If you’re just resealing one or two windows, it’s actually cheaper to buy the materials we list above (and it’s just as effective).

How to Replace an RV Window Seal Step-By-Step

  1. Before removing the window, remove the screws on the interior of the RV frame and remove the clamp ring. Remove or loosen any caulk along the edges to help with a smooth window removal.
  2. Using two people, one inside and one outside, work together to remove the window, being careful not to break the glass pane.
  3. Once the window is removed, use a putty knife to remove old sealant from both the window trim and your RV, if there is any.
  4. Clean the window and exterior with alcohol.
  5. Install the new butyl sealant tape by starting at the bottom, where there are weep holes. Make sure there are no gaps left between the sealant and the window.
  6. Apply the replacement seal tape about 1/8 inch from the window’s edge, overlapping 3/8 of an inch where they meet at the bottom.
  7. When reinstalling the window, use two people to make it easier to set it into place.
  8. While one person is outside holding the window in place, the person on the inside can now screw the window back in. Start with the upper left screw, then lower right, lower left, and then screw in the upper right corner of the window. Once the corners are screwed in, you can move on to the middle screws.
  9. Complete the process by applying the sealant to the top of the outside window frame and around the upper corners.
  10. Smooth the seal with your finger.

Your RV window should now be properly sealed! Check out our ultimate guide on how to seal RV windows for more tips and tricks to get the perfect seal!

How to Prevent RV Window Seals From Shrinking

Chances are, if you’ve had to deal with your window seals shrinking and subsequently having to fix the issue yourself (or paying good money to get it fixed), then you probably don’t want it to happen again.

Thankfully, preventing this from happening is pretty easy and doesn’t take much time or money!

Avoid Prolonged Exposure to Elements

Temperature extremes, rain, and sunlight all cause the seals on your windows to deteriorate over time. You can minimize seal damage from the elements by:

  • Storing your motorhome in a covered, dry place when not being used for extended periods of time.
  • Avoid leaving it out in inclement weather when possible.
  • Park your recreational vehicle in the shade or out of direct sunlight when possible.

Proper RV Window Seal Maintenance

Maintain your seals by cleaning them regularly and applying a protectant to them like 303 Protectant Spray.

Make this routine maintenance a part of your camper de-winterization process, so you don’t forget.

A little know-how and proper maintenance will go a long way in keeping your RV window seals in good condition.

303 Marine & Recreation Aerospace Protectant

303 Marine & Recreation Aerospace Protectant

Buy Now on Amazon

Clicking this link to make a purchase may earn us a commission at no additional cost to you.

Professional Installation

If you’ve replaced your shrunken window seals only to have them shrink again, then it may be time to call in a professional.

Improper installation is a common cause for sealing to shrink, as is using inferior sealant products.

If you’re continually having issues with your window seals, I recommend getting them professionally installed.


What Happens When a Window Loses Its Seal?

When an RV window starts to lose its seal, you may notice moisture building up on the window, air and water leaks, or… you may notice nothing at all. Either way, you will want to fix the seal ASAP before it becomes a bigger issue and potentially creates more damage to your RV.

Do Windows With Broken Seals Need to Be Replaced?

RV windows with broken seals rarely need to be replaced unless there is damage to the window itself. Instead, you will just need to replace the seal to prevent any leaking issues from happening.

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