RV Window Seals Shrinking? Why & How to Fix It

Shrinking RV window seals can be caused by a variety of things including age, temperature, sunlight, and more. With that said, fixing shrunken RV window seals is not the hardest task in the world.

One of the best methods for fixing a shrunken RV window seal is to stretch them out. You may also be able to heat it up. If none of these things work, then you may need to replace it.

RV window seals shrinking

Why Do RV Window Seals Shrink?

First things first, let’s figure out why the seals on your RV’s window have shrunk. Shrinking RV seals can be caused by a number of reasons.

One of the most common causes is simple wear and tear. Overuse, combined with old age can definitely cause those RV window seals to shrink.

What can also cause RV window seals to shrink is sunlight. There are many materials out there that are susceptible to degradation due to exposure to UV rays from the sunlight.

Silicone, rubber, and other such materials generally don’t handle sunlight well. It causes the silicone or rubber to dry out and therefore to shrink.

This is also the case if we’re talking about big temperature fluctuations. Extremely hot and dry air can dry out that sealant, and cause it to shrink. Great temperature fluctuations from hot to cold, over and over again, may also cause this to occur.

Now, if your RV is fairly new and you notice that the RV window seals are already shrinking, they might have just been improperly installed.

On a side note, before you attempt to fix or replace your RV window seals, it’s always a good idea to check the warranty.

If the window seals are still covered by the warranty, there is absolutely no point in trying to do anything yourself.

Signs That Your RV Window Seals Are Shrinking

There are a few different telltale signs that the window seals on your RV are shrinking or have already shrunk. First and foremost, you want to test to see if there is any airflow present.

This is of course the main purpose of an RV window seal, to prevent airflow through the gaps between the window and the frame of the RV.

Therefore, you can hold your finger, a piece of paper, or even a candle next to the window seal. Move any of these objects around the window seal to see if there is any kind of breeze. If there is a breeze and you can feel some wind, then the seal has shrunk.

What you can also try doing is visually inspecting the seal. If you see that the window seal is no longer properly attached to various areas around the perimeter, then it has shrunk.

If you can’t see it with your naked eye, try testing it with your hands. Just go all along the perimeter and gently tug on the window seal to see if it is loose in any one place.

Next, another thing you can do to see if the RV window seal has shrunk is to poke at it. If the window seal has shrunk, chances are almost 100% that it has dried out.

If this is the case, the seal will feel hard and brittle, and also have cracks in it. If the window seal has not shrunk, it should also not be dry, and therefore still be soft and pliable.

How To Fix/Replace RV Window Seals

There are a few different methods to repair or fix shrunken RV window seals. We are going to discuss both of the best methods below. Then, in case you cannot repair the shrunken RV window seals, you will have to replace them, which we will also discuss below.

Do keep in mind that if the RV window seal is extremely damaged, such as if it has large cracks, then you will need to replace it.

While you can stretch out these window seals, you can’t really repair them once they are broken.

1. Stretch the RV Window Seal

If you’re RV window seal has shrunk, the best thing you can do is just stretch it out. To do this, you are going to need to remove the window seal from the window. Once you have removed the window seal, you then want to apply a whole lot of 303 protection spray to the seal.

 For this purpose, more is generally better, so really soak the windowsill with the spray. You then want to use your hands to massage that spray into the window seal as much as you can. You want to do this while simultaneously stretching it out.

You can use a good deal of muscle to stretch out that window seal. Just don’t apply so much force that you end up tearing it in places where it may be cracked. Once you have stretched it out and lubricated it, you can then put it back in place.

2. Using Heat

Another method that may work to stretch out the window seal is to apply some heat to it. The easiest way to do this is to use a hairdryer and directed at the window seal.

Direct it at each area of the window seal for about 5 to 10 seconds. However, make sure that you don’t use the highest heat setting, and don’t apply heat for longer than 10 seconds.

Excessive heat may damage the window seal. However, heating it up should allow you to stretch it out a bit. If you want to take things to the next level, you can heat it up while simultaneously engaging in the above method, applying that 303 protection spray.

All of that said, while both of these methods are ideal for stretching out a shrunken window seal, if it has cracked or is broken in any way, you will simply need to replace it.

If this is the case, and your RV window seal needs to be replaced, refer to the steps listed below.

3. Replacing The RV Window Seal

Follow the steps listed below to replace your RV window seal.

  1. You first need to remove the screws on the inside of the frame of the RV, and then also remove the clamp ring. You’re also going to need to loosen or remove any caulking along the edges of the window.
  2. You need to have two people for this job, one inside and one outside of the RV. Be very careful when removing the window. Yes, you need to remove the window to complete this task.
  3. Use some kind of scraper or putty knife to remove the old sealant from the window. Remember, you need to remove the sealant from the window and the window trim.
  4. You now need to clean all affected areas, including the rim of the window as well as the window itself with alcohol. You need to have a perfectly clean surface when you go to install the new RV window sealant.
  5. Starting at the bottom where the weep holes are, you need to install new butyl sealant tape. Make sure that there are absolutely no gaps at all. Be sure that you apply this new sealant tape about an eighth of an inch from the edge of the window. You also want to make sure that it overlaps about 3/8 of an inch where it meets at the bottom of the window.
  6. You now have to reinstall the window itself, and then screw everything back into place.
  7. You now need to finish this process off by applying the sealant of choice to the top of the window, specifically on the outside of the window frame, as well as around the upper corners of the window. Of course, the specific sealant you use depends on your model of RV.
  8. You can now smooth everything down with your fingers.

How To Prevent Camper Window Seals From Shrinking

There are a few tips for you to follow that can help prevent those RV window seals from shrinking in the first place.

  • Simply applying that 303 protectant spray on a regular basis, about once per month, should help keep them well maintained and help prevent them from shrinking.
  • To prevent those RV window seals from shrinking, a good idea is to have them professionally installed in the first place. It helps a lot if they are professionally and properly installed.
  • Whenever you store your motorhome for a prolonged period of time, always make sure to store it in a dry and covered place. You never want to leave your RV out in inclement weather, as this can definitely cause your RV window seals to shrink.
  • You also never want to park your RV in direct sunlight, so keep it covered.
  • In terms of the interior of the RV, when using it, try not to perform excessive heating or cooling, especially right after one another. Temperature fluctuations can quickly cause those RV window seals to shrink.

Should You Caulk Around RV Windows?

The answer to this question is yes, you should caulk around RV windows.

Caulking can help protect your windows from moisture and air leaks, as well as damaging UV rays and extreme temperatures. I

t also prevents insects from entering your RV and provides a better seal for weatherstripping, ensuring that your windows stay secure in even the harshest of weather conditions.

Caulking RV windows is a fairly simple process, but it does take some time and effort to get it right. If you are not confident in your abilities, it’s always best to enlist the help of an experienced professional who can do the job safely and correctly.

When applying caulk, make sure to use a good quality caulk designed specifically for RV windows.

Be sure to follow the instructions on the packaging and take your time doing it, as any mistakes could result in leaks or other damage.

Once you have applied the caulk, let it dry completely before closing up the window or putting anything else near it.

What Is The Best Sealant for RV Windows?

The best sealant for RV windows is one that is designed to be used outdoors, such as a high-grade silicone caulk that can withstand extreme temperatures and UV rays.

Make sure to read the manufacturer’s instructions carefully and follow them closely in order to get the best results.

You can choose any brand you prefer, but some popular ones include Dicor, Geocel, and Polyseamseal. All of these brands are highly rated for their quality and durability when used on RV windows.

Caulking your RV windows is an important part of maintaining your RV, so don’t neglect this important task. With the right tools and a bit of patience, you can make sure that your windows stay safe and secure for years to come.


How Often Should I Check My Camper Window Seals?

Generally speaking, inspecting the window seals of your RV is best done once per year. With that being said, if your RV has been out in inclement weather, or you just use it a lot, then checking those seals two or even three times per year is recommended.

What’s The Cost of RV Window Seal Replacement?

If you replace the RV window seal on your own, it could cost you about $100. However, if you want a professional to do it for you, you could spend a few $1000. This is especially the case if you have multiple windows that need to be newly sealed.

Madeline Cooper