Whoever thinks about RV window seals shrinking? Not us! When we first bought our camper, window seals were not a part of our selection process.

We all look at the windows themselves to imagine the views we’ll see. Or maybe we look at the composition of the windows. We ask what they are made of and how they open and close.

But no one gives a second thought to the window’s rubber seals…until they start to shrink and leak, that is. Unfortunately, window seals do shrink over time.

And that shrinkage can leave a gap between the window and frame. Cold air seeps inside, while your warm air seeps out, leaving you with higher propane costs and chilly temperatures.

Sometimes these gaps do worse damage by allowing water to drip into your RV. This moisture leads to soft, rotting wood and structural damage.

Knowing why window seals fail is the first step in fixing the problem, even before it starts.

Let’s take a look at why your window seals shrink and how to maintain them in good condition, so you can get back to enjoying the views!

What makes a good Window Seal?

A good window seal acts as a protective barrier between the RV’s walls and its windows. Some RVs have caulk around the outside of the window, in addition to the seals.

Together they protect the RV from weather and water damage, while providing us the beautiful views we desire while camping.

Why do RV Window Seals Shrink?

Why do RV Window Seals Shrink

Over time, seals of your camper’s window shrink because of age, temperature variations, weather extremes, and normal wear and tear.

As rubber ages, it causes the pressure of seals to decrease over time.

The rubber dries out, becomes rigid, and literally begins to shrink. This happens naturally, simply due to time and normal use.

Weather variations

Weather extremes also add to the shrinkage of RV window seals. Cold winters under 30 degrees Fahrenheit (-1 degree Celsius) wreak havoc on rubber.

It contracts with the cold, only to later expand with the RV’s heater. Summer weather is also hard on the window seals, since extreme hot sunshine causes the rubber to crack.

Rubber quality

Sometimes manufacturers use low-quality rubber for their seals, which adds to the problem of shrinking and cracking.

No one wants to think of manufacturers taking shortcuts, but honestly, sometimes they do.

Bumpy conditions

Beyond temperature variations and potential low quality seals, RV’s regularly take a beating as they simply drive down the road.

The bouncing and jostling caused by rougher campground roads can jar window seals loose.

Windy conditions also loosen the seals, allowing for particles of sand and dirt to lodge underneath.

Those particles grind away over time, much like sandpaper, and they cause the rubber to further break down.

How to Tell if a Camper’s Window Seal Has Failed?

How do you know if you have a problem

Recognizing you have a problem with your window seals shrinking goes a long way towards addressing the issues. There are several ways to tell if your seals need attention:


If you are in a drivable RV, such as a Class A, B, or C, you may be able to hear the wind come through the window seals as you are driving down the road.

It’s a loud and annoying sound, but can also indicate that an issue is arising.

Newer RVs may still be under warranty if you notice cracking or leaking soon after purchasing your camper.

The problem might be poor installation, rather than failure of the seals themselves. So always check with your RV dealer prior to undertaking repairs.


You can obviously tell if you have a problem with shrinking window seals, if you see water dripping in. But sometimes the water drips within the wall and is much harder to locate.

Another visual way to tell if you have a problem with your window seals is by thoroughly inspecting the seals themselves.

Are they cracked? Are they pulling away from the window? Can you see water pooling in the corners? These are some of the things to keep in mind during your routine inspection.


Gently pressing the wood beneath the windows will alert you to a potential soft spot. Also visually inspect for any bulges or bumps in the walls around and under the window.

These soft spots may also show up behind a countertop, if the seals in your kitchen window are shrinking and failing.

The worst case scenario for telling if there is a problem is your window popping out due to damaged and deteriorated seals.

This is the most extreme occurrence, which should hopefully never happen if you are doing regular maintenance and inspection checks.

What are the consequences of poor window seals?

If your RV window seals have shrunk so much that you have gaps, water can come in.

You may not see it, if it simply drips down a wall. But that can cause damage to the wood around your windows, possibly even down to the floor.

When water sits on (or drips into) wood over prolonged periods, the wood begins to swell and rot.

Repairing a section of wood and siding comes at a much higher cost than simply checking and maintaining your seals regularly.

A big concern from RV window seals shrinking is the possibility of mold and mildew within your RV.

Especially in damp weather climates, dripping water can lead to serious health issues.

If you’ve had to make costly repairs because of window seals shrinking, then you know that a little bit of prevention is definitely worth a pound of cure!

How to Prevent RV Window Seals From Shrinking

How do you Protect Against RV window seals shrinking

Taking steps to protect against RV window seal shrinking saves you time, money, and heartache.

By preventing the problem, as much as possible, you extend the overall life of your RV.

Protect from Weather Damage

Weather damage is one of the largest factors in the deterioration of window seals.

The extremes of temperature cause swelling in hot weather and then contraction during the winter cold.

You can make a difference in mitigating damage by taking these steps:

  • Store your RV under cover, preferably in a shop or garage when possible.
  • Use an RV cover if storing indoors isn’t an option. This will protect your paint as well as your window seals.
  • Park in the shade, out of direct sunlight.
  • Salty air along coastlines adds to the deterioration of window seals. Be sure to rinse and dry your seals after prolonged beachside trips.

Perform regular maintenance tasks

Performing regular maintenance is the key to all RV ownership, but it especially applies to deterring your RV window seals from shrinking. Inspect and maintain. Those are the main points. Inspect and maintain.

  • Check for small cracks, brittle rubber or missing seals.
  • Check for leaks after washing your RV and after rain showers. Check around the window seals for any hints of pooling or dripping water. Ideally, you should see no dripping, just like within your car.
  • Add checking the roof and wall joints, as well as the gutter rails, above each of your windows to your regular maintenance checklist. If there is failure at one of these points, water may continuously stream down to your window seals. That flow of water could damage your window seals as quickly as occasional rain would.
  • Keep your window seals clean but beware of using high-pressure water hoses, as they may tear or damage the seals.
  • Dirty scrub brushes and washrags could also contain cleaning chemicals that break down the rubber. So be sure to rinse well and dry the seals after washing.

How to Fix the Seal on a Camper Window?

There are several ways to repair RV window seals, depending on the level of damage, your budget and your time constraints.

If you’re on a trip and notice an issue, it’s okay to use caulk as a temporary seal.

Just be sure to dive into the issue deeper upon your return home to fix any larger problems quickly.

Stretch the Seal

Stretching the seal is the most common way to address RV window seal shrinking. It’s also the most cost-effective, so this is a good place to start.

It’s always a good idea to see what your own manufacturer recommends but start by removing the seal from the window.

Spray it with 303 Protectant Spray and then rub the spray into the rubber. Just get in there and get all dirty, you can wash your hands later.

Or wear rubber gloves, if that’s your thing. Either way, just give that seal a good old-fashioned massage.

Seriously though, getting the protectant spray into all the tiny crevices will renew and restore the rubber.

Return the seal to the window and you should be good to go.

Apply Heat to the Seal

Protectant spray is a good way to stretch the seal. But if you find that it is still a little brittle or not quite as supple as you think it ought to be, then applying heat in addition to the spray may help. Simply heat the seal with a low-temperature hair dryer.

Smooth and stretch while heating until the rubber seal feels pliable again. Then reinstall around the window.

Whether using protectant spray or applying heat, take time to visually inspect the seal. Repair any cracks over 1/8″ long to discourage further damage.

Replace the Seal

You can purchase an entire window sealing kit to replace the seal if you think it is beyond repair.

Dicor Corporation sells a kit to replace seals on six to eight windows for less than $100.

Especially if you are buying a used RV, this may be the best way to go. You can start fresh and know that your window seals are in good condition.

Dicor is a well-respected brand in the RV community. In addition to window seal kits, they make self-leveling roof sealants and caulking for RV side seams.

This (or a similar) window seal kit is easy to install and is an affordable way to prevent leaks and drafts.

The steps to replace your window seals are fairly easy, but it might be nice to have a partner nearby to share in the lifting.

Also be sure to consult your own RV manufacturer’s guidelines for any special points of awareness.

  • Remove your window and then carefully remove the old seals.
  • Take care to use a plastic scraper when cleaning any remaining caulk or seal from the window.
  • Clean and dry the entire window and don’t forget the frame too.
  • Press the new seal into place around the frame and then re-install the window.
  • Caulk from the outside, as needed. Use a good, flexible RV sealant, not regular silicone caulk that you find at a hardware store.

Do Camper Windows with Broken Seals need to be Replaced?

Do Windows with Broken Seals need to be Replaced

There is no reason to replace your RV’s windows, just because the rubber seals need to be replaced.

Inspect the window carefully while repairing the seal. As long as it’s free from chips, cracks or damage itself, you can reinstall the window and keep using it.

If for any reason, the window no longer fits properly after replacing the seals, you might need to look at replacing it.

Generally, this only happens in older RVs where things have shifted over time. If in doubt, replace the window now to save yourself a headache and extra money in the future.

So What does it Cost to Repair RV Window Seals?

Like I mentioned above, you can buy a kit to replace 6-8 windows for under $100.

Compared to repairing water-damaged wood, this small investment can save you hundreds, if not thousands of dollars.

Removing your window seals to lubricate with 303 Protectant Spray costs around $15, plus your time.

Both options to lubricate or to replace the seals are easy jobs to do yourself.

It may take a couple of hours of your time, but with a little skill you can save yourself the cost of a shop’s labor.

Taking your RV to a shop to repair your seals will cost between $75-100 per hour of shop time. So you can see the significant cost savings by doing this repair yourself.

What Else Do You Need to Know about Window Seals Shrinking?

Nothing. That’s it. Regular inspections and maintenance make the largest difference when it comes to all RV ownership.

Ensuring that your window seals are in good order without leaks, cracks and damage will protect your investment for many years to come.

Once water gets into your camper, problems arise, so don’t let it happen.

Inspect and maintain your window seals to increase the overall life of your camper. That way it’ll be ready for making happy memories with your family and friends.