RV Window Seals Shrinking? Here’s How To Fix Them

If you’re noticing that your RV window seals are shrinking, it’s time to take action. This is a sign of the sealant wearing out and will lead to leaks in your camper. Here’s how to fix them!

You can use silicone caulking or butyl rubber sealant for this project. You’ll also need a hot air gun or a hairdryer, and a putty knife. If you have to replace the seal, you’ll need a screwdriver as well.

How to fix the seals on an RV window

Stretch the seal to make it flexible again

One of the most common reasons window seals shrink is because they dry out. This is the easiest fix, and you should try fixing this before anything else.

  1. Remove the seal
  2. Spray the seal with a good amount of 303 protective spray
  3. Wear some gloves and massage the liquid into the seal
  4. Replace the seal on your window

The 303 spray is very potent and it can breathe new life into your window seals. That should most likely fix the issue.

If it didn’t work for some reason, try the next solution.

303 Rubber Seal Protectant - Protects And Conditions Rubber Seals On Doors, Windows, Hoods, And Trunks - Rejuvenates Color On Old Seals, 3.4 fl. oz. (30324)

Heat the seal and stretch it out

In order to heat the seal and stretch it out, you need to first remove it.

When you first start out, be sure that the seal is dry.

Next, turn the hairdryer on and direct it at the seal until it is hot. It should be a little bit easier to stretch down low for this.

You will likely need to repeat this process a few times until you feel like the seal has been stretched enough for it to go back on your window again.

As an added level of protection, consider spraying 303 again to maintain the stretchiness.

Replace the rubber window seal

If the above two methods did not work, it’s time to get a new seal.

  1. Start by removing the old seal. Use a screwdriver to remove the screws on the RV frame interior and remove the clamp ring.
  2. Very carefully remove the window from the RV. Use two people if possible, one standing outside and one inside! The glass is heavy and you don’t want to drop it!
  3. Use a putty knife to clean the frame of the RV and the window of any residual sealant
  4. Clean the window and RV exterior with alcohol.
  5. Apply new butyl sealant tape at the top to the window’s opening so it creates an airtight seal.
  6. Then apply butyl sealant tape at bottom of the window so it covers the weep holes. Make sure to overlap at the bottom, where they meet.
  7. The window should be replaced by two individuals to make the job easier.
  8. One person can now screw the window back in after one person outside holds the window in position. Place the window in position, install the upper left screw, then lower right, lower left, and finally fasten the top right corner of the window. You may now turn your attention to the middle screws.
  9. After that, apply the sealant to the top of the outside window frame and around the upper corners.
  10. Finally, smooth the seal with your finger.

Why do RV window seals shrink?

RV window seals are the soft vinyl or rubber seals that attach to the glass of your windows and provide a tight seal when your windows are rolled up or closed.

After time you notice that they either do not touch, don’t fit flush with one another, or in extreme cases even come off.

This leaves you with an undesirable appearance and may allow bugs in when it is raining or if it has rained recently (if you can even get them closed at all).

As always I like to look into things further before giving my opinion on any matter so I decided to see what my research turned up.

Keep reading to find out why they shrink in the first place…

The answer to this question is complex and multifaceted, but the main reason window seals shrink is because over time they dry out and become brittle.

Vinyl and rubber by nature will slowly deteriorate with age and exposure to sunlight. This deterioration process accelerates when the vinyl or rubber material becomes overheated which can happen if it sits in direct sun for long periods of time.

Even just sitting in a hot garage overnight instead of being stored under cover can cause these materials to be permanently damaged.

If left like this long enough your window seals might start cracking, become hard and stiff, or may even completely fall off!

On close inspection you should find some information stamped into the window seal itself.

If you do find such information there should also be a date stamped into the material. If not then it is impossible to know when your seals were actually manufactured or what company made them.

Replacement seals can usually be purchased at an RV supply store if they are available, but if they are discontinued then only the original manufacturer will have replacements for sale (if available).

If looking at new window seals just keep in mind that anything over five years old should probably be replaced because chances are they have deteriorated to some extent even if they still appear flexible and soft.

Replacing these parts regularly might help prolong the life of your trailer by decreasing general wear and tear on other components, however there is no guarantee that you will not have one or more window seals fail anyway.

Other reasons RV window seals shrink

There are some other possible factors which may lead to your vinyl or rubber window seals shrinking.

Any of the following could potentially cause your seal material to shrink: If there has been a recent change in climate (humid air versus extremely dry air) then it is possible that your windows are fogging up after being closed due to condensation building up along the inside of the glass .

You may notice that water has accumulated on top of the rubber sections of your window seals when this happens. If left open too long while this happens then water can also accumulate on the inside of your windows under the seal material which will accelerate its deterioration.

If this is an issue for you then just try to keep your windows open slightly whenever it looks cloudy outside, but close them up again when you are about to go camping. Leaving them cracked overnight often prevents this problem from happening at all…

Just be careful not to leave any curtains or coverings over your windows if possible because they help trap the moisture instead of allowing it to dissipate into the air.

You may have noticed that some campers with slide-out sections (including many RVs) tend to develop a “wave” in one section of their window seals as they expand and contract while moving up and down .

This is caused by the fact that their windows do not seal properly when in the down position (may also indicate a bad or missing window sweep). If your door seals are completely sealed and water tight when closed then this may be less of an issue because there will be no direct path for rain to enter.

Once again, always make sure your windows and doors are closed tightly at night if leaving your trailer exposed to precipitation overnight!

Finally, having too much tension on your window seals is probably the most likely reason why they have shrunk or are ripping apart more easily than before .

You can test out this theory by simply pulling on different sections of your rubber seal with all of the windows rolled up. If you feel more resistance any particular point along its length then it is likely that more tension is being put on that section of the seal than was originally intended by the manufacturer.

This can happen when your trailer either hangs down too low or rides up higher than normal after having weight added to it (such as while camping). If one end of your RV is dragging more on the ground then an excessive load has probably been distributed across only half of every window seal, causing them to shrink more in length at some points and stretch more at others .

It might be able to be fixed with some additional material along the bottom edge, but this will require some custom work so may not always be possible depending on your specific situation.