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How to Fix a Leaking Tonneau Cover and Make It Waterproof?

A big concern for truck owners with tonneau cover during rain is, worrying about water leaking through the tonneau cover.

As nobody wants water to ruin their precious cargo and waterproofing the tonneau cover is the best possible option. That is exactly what this guide is for.

In this article, I will walk you through step-by-step processes on how to fix a leaking tonneau cover and waterproof it.

There are quite a few waterproofing options, but they follow the same principle, and I will discuss that in detail. 

I assure you that you will be able to understand all of these fixes, and by the end of this blog, you will know everything regarding how to waterproof your tonneau cover.


Why Is Your Tonneau Cover Leaking?

The first thing you need to address before you can start waterproofing your tonneau cover is to find the reason behind the water leaking. 

Most of the time, water leaks on the tonneau cover occur due to gaps between the bed rail’s top and the tonneau cover. And if your cover is damaged or cut in certain places, then water can slip through them as well. 

Improper placement of the tonneau cover can also cause water leakage. Moreover, not having the right size of tonneau cover may also be why your cover is leaking.

Once you have determined the issue, you can take steps to prevent the leaking.

If you find that the leaks are caused by placement issues like small or big tonneau cover compared to the truck bed or improper installation, then you might not need to opt for waterproofing your tonneau cover.

That being said, it is always best to waterproof your tonneau cover. This is because you might not need it now, but soon the initial waterproofing of the tonneau cover will fade, and you will face water leaks anyways.

So, it is better to waterproof the tonneau cover before facing any leaks whatsoever!


How Do You Seal and Waterproof a Tonneau Cover? A Step-by-Step Guide

Now, there are several ways you can waterproof a tonneau cover. You can use bed seal kits or do complete insulation of water pipes.

No matter the option that you pick, the basic principle is that you need to seal your tonneau cover so that water doesn’t enter the truck bed.

Here are the steps that you must follow to ensure that you can perfectly seal and waterproof a tonneau cover:

Step 1: Get the Required Tools  

Before you can proceed to the sealing process, you need to get the necessary tools at your disposal first. The tools you might need vary depending on the type of sealing you are going for.

Generally, the required tools are the following:

  • Paper towels 
  • Rubbing alcohol
  • Scissors or knives
  • Sealing kit or seals 

However, you might need to use heaters if you are planning to reseal your tonneau cover. 

Step 2: Take Out the Tonneau Cover & Clean It

There is no way you can seal your tonneau cover if it is still attached to your truck now, can you? So, take it out first and start to clean it with paper towels. 

I recommend you ask for a friend’s help when taking out the tonneau cover as they can be very heavy, and you can hurt yourself if you are not careful.

Once the tonneau cover is out, thoroughly clean it from top to bottom. There shouldn’t be any traces of dirt or dust on the cover.

Otherwise, the adhesives from the sealer won’t work properly & all the hassle will be for naught.

Step 3: Apply Rubbing Alcohol

Next, you need to apply rubbing alcohol where you will be placing the seals.

That means you use rubbing alcohol on the edges and the corners of the tonneau cover. Basically, you cover the entire surface.

If there are any open spots on the tonneau cover, then you have to run through there as well, as you need to put extra seals there.

Step 4: Installing the Seal

Once you are done mapping out and applying the rubbing alcohol, you need to install the seals. Take out the part that covers the seal’s adhesives and then slowly apply it from one side of the tonneau cover. 

You can use scissors or knives to cut out where it is necessary. Remember, the bulb side should be facing up. Slowly cover the entire area. 

Once you are done with the seals, let them rest for ten minutes, you shouldn’t put pressure on them during that period; let them naturally set in. 

Step 5: Testing the Seals

Once the seals settle in, it’s time for you to test if they are actually working or not. The easiest and the most common option is to turn on a garden hose and pour water on the tonneau cover. 

You can also do the light test, where you turn on a very bright one and try to see if any light is breaking out from the other side. If you do this, I recommend you use sunglass.

If you are satisfied with the results, then the waterproofing process is complete.

That’s it! This is how you install seals to waterproof your tonneau cover. 

Photo of author

Kevin Shaw

Editor-in-Chief at F150Lab

Kevin Shaw has a vast knowledge of pickup trucks, especially the Ford F150. He has been doing various DIY fixes, upgrades, and modifications to pickup trucks for more than five years now.

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