How To Fix A Leaking Tonneau Cover – Quick & Easy At-Home Repairs

Yes, a tonneau cover’s main feature is to defend our belongings from getting damaged or wet. But things can happen – and every now and then, something could prevent your trusted truck accessory from fulfilling that task.

One of those things is potential damage to the tonneau cover – or its water drainage system. If that ever happens to you, don’t rush to buy a new one immediately, though.

Sure, finding the root of the leak – and fixing it – could take some time. But with a little effort and proper guidance, it can be done – which is kind of the point of this entire guide.

So, stay tuned to learn how to fix a leaking tonneau cover!

Don’t Be Rough With Your Tonneau Cover!

How To Fix A Leaking Tonneau Cover - Quick & Easy At-Home Repairs

Regardless of the truck you drive, if it has an exposed bed, then you’ll need a tonneau cover. There are different types, styles, and designs found on the market, and the most sought-after ones seem to be the tri-fold and roll-up tonneau covers.

Choosing either one of those is fine. But buying a tonneau cover won’t give you the necessary knowledge on how to keep that same cover functional and take good care of it.

This guide could help with that, though.

Obviously, you should handle the tonneau cover with care. Still, accidents will happen – and it’s essential to address them as soon as they do.

In the case of tonneau covers, the usual things that go wrong with it are either a malfunction with the closing mechanism or any form of physical damage that can cause the cover to leak.

Now, most of those malfunctions will occur if you rip, puncture, or tear the cover. But in some cases, damaging the rail system of your tonneau cover could lead to a leak, too.

The first is relatively easy to solve:

You’ll need to dismount the tonneau cover, disassemble it, and – yup, you guessed it – reassemble it from scratch. In nearly all cases, that alone will solve that problem.

But what happens when you have a leakage problem on the tonneau cover itself?

Is that something that you can solve just by reassembling it from the ground up? I’ll be honest here – more often than not, fixing the issue will require more than just a quick dismount-disassemble-reassemble-install process.

But we’ll get to that. For now, let’s see how you can find the exact area that’s causing you trouble.

Try To Pinpoint The Location Of The Leak

How To Fix A Leaking Tonneau Cover

One of the fastest ways to test the tonneau cover’s functionality and pinpoint the leak’s location is to use the so-called rain method.

With the tonneau cover fully closed, you use a garden hose and spray the top portion with water in an upwards motion, letting it fall naturally. You’ll essentially simulate rain – but in controlled conditions.

If you do that, it’s highly recommended that you take your stuff out of the bed of your truck first. Duh.

Depending on where the leakage problem is located, you could end up unintentionally soaking cargo that’s protected by the tonneau cover. Or rather, cargo that should’ve been protected if it weren’t for the leak.

That’s one piece of advice.

Another one – and this one might not be as obvious – would be to place a large piece of cardboard onto the truck bed, covering it completely. Due to the water-absorbent nature of cardboard, it should be easier to find the wet patches and see where the cover leaked.

And now, make it rain.

After several minutes, pause with the spraying and see the results.

If some water made its way inside your truck bed, I suggest that you proceed with the next step – just to be absolutely sure where the leak is.

Now, for this next part of our little find-a-leak experiment, you’ll need to have a strong flashlight and a helping hand.

You can tell where this is going, can you?

As you turn on the flashlight, carefully inspect every inch of the tonneau cover, especially the four edges of the cover and both rail systems. The other person should be inside the truck bed, looking for where the light seeps through the cover.

Depending on which problem you have, you’ll either need to find a crack in the rail system or a hole in the cover.

Using a flashlight is highly beneficial – without one, you might miss the exact tear that’s causing the leak. And it doesn’t take much, might I add.

Even a hole that’s a fraction of an inch wide can cause a leakage problem on a tonneau cover.

When you locate the area that’s damaged, you’ll need to mark that spot. It doesn’t matter how you’ll mark it – a pen, chalk, or tape – as long as you remember the exact location of the damaged spot.

I mean, how would you repair it otherwise?

Usually, when it comes to a leakage problem on a tonneau cover, several points need to be treated. Because of that, don’t stop searching as soon as you find one spot that’s damaged.

Continue this process until you’ve covered every inch of the cover.

Remove Your Tonneau Cover From Your Vehicle

Fortunately, tonneau covers are easily disassembled – especially if you own a unit that doesn’t operate on a retractable system. So, as you can guess, tri-folds and roll-ups are easier to repair.

But you can implement these tips even on retractable tonneau covers.

Start by disassembling your tonneau cover. I highly recommend taking your manual for the tonneau cover assembly process and reading it from the end to the beginning.

Following the steps in that order won’t cause any damage to the tonneau cover, by the way. It will help you retrace your steps.

If you threw away the manual, then you’ll need to hear me out:

Depending on which tonneau cover you own, you should start by opening it completely. After you open it, you’ll need to locate the pin that connects the cover with the rails.

Use the pin to disconnect the cover from the rails and place the cover on a flat area.

After that, you should take off both tonneau cover rails that are attached to your vehicle. It might take some time. But it’s necessary to do that in this order.

After you fully disassemble the tonneau cover, take a closer look at all of the components. When it comes to a leakage problem on tonneau covers, the usual culprit is something that’s broken – thinks tears and rips – or missing.

After you examine the tonneau cover completely, you’ll have one of two choices:

  1. If you found a hole in the cover, then you’ll need to either sew in a stitch or two until you close that hole – or find another way to seal it shut, to the point of it not leaking ever again. Even duct tape would work.
  2. If you notice a crack somewhere in the rail system, you’ll have to use a slightly different approach. The easiest solution here is using some silicone to fill the gap formed by the rail system crack.

You don’t need to stop with the silicone:

You can use any material that you see fit, including seal strips. As long as you can use it to close the hole and as long as that material is waterproof, then you’ll be good to go.

Reassemble the tonneau cover after you finish the treatment and mount it on your vehicle.

Now, take that garden hose and make it rain again for a few minutes. If there isn’t any leaking inside your truck bed, it’s safe to assume that the problem is resolved!

Although the steps above will, most likely, resolve your leaking tonneau cover problem, it’s worth noting that two other methods can be helpful when dealing with potential future leaking problems.

Let’s take a look, shall we?

Add A Seal (Or Two)

If the leaks aren’t too big – and I hope they’re not, for your sake – adding additional seals might be the right solution for you. Here’s what makes them so great:

They’re easy to find – a quick walk to the local hardware store should do it – and they’re pretty affordable, too.

There are two things you should pay attention to, though. One, make sure that the seal matches your tonneau cover’s color. And two, make sure it’s big enough to cover your leaks.

Consider Adding Drainage Pipes

Another option – and a rather popular one, might I add – is installing water pipe insulation to fix a leak in a tonneau cover. Again, it’s cheap, readily available, and easy to install.

I know it seems a bit unconventional, but water pipes already have rubber insulations, slits on the side, and adhesive. They can patch the gaps pretty much immediately.

And here’s the best part:

They’ll also make the tonneau cover firmer, allowing excess water to drain rather than accumulating on the cover.


Just because you notice that your trusted tonneau cover is malfunctioning, that doesn’t automatically mean that you should hop on the Internet and get a new one.

Most tonneau cover issues can be easily resolved – as long as you know how to fix a leaking tonneau cover, that is.

It’s necessary to pinpoint that location and treat it accordingly. Save your cargo from getting unnecessarily damaged or wet by fixing the leak in the cover as soon as possible.

It might take some time – but it’s better than buying a new one!

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