A Detailed Guide of How to Stop Tonneau Cover from Leaking

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Stopping a tonneau cover from leaking requires two things: 1, the right fit, and, 2 proper installation.

While tonneau covers are great protectors from the elements, water will inevitably filter through into the back. Be it because of a gap, wear and tear, or poor design, leakage is unfortunately inevitable. This can be incredibly frustrating, especially if you don’t want what you are transporting to get wet.

Luckily, we can take matters into our own hands and add personal modifications and improvements to the already near-waterproof cover to make it entirely waterproof.

So, without further ado, let’s take a look at how to stop tonneau cover from leaking without it taking too much time or money.

Finding and Preparing For Leaks

Sometimes the leak is caused by a significant and noticeable gap between the bed and the tonneau. Sometimes, the leak is more discreet and difficult to find. A surefire way to figure out where the leak is, is to leave the cover as you would while driving but have the tailgate open.

Now, while pouring water over the cover to simulate rain, you’ll be able to see where the drainage occurs. Masking tape or a bright, non-permanent marker is then ideal for marking the spot, so you can keep your place when you remove the cover to do repairs.

Should the leaks be along the edges of the cover, or close enough for it, silicon seal or strips of the given seal are perfect to fit the size of the leak.

When cutting the seals to match the leak, it is crucial not to make a seal in one place only to divert the leak somewhere else. This process can be repeated once you’ve sealed a few leaks to find new ones that you may have missed.

Repairing Leaks in the Cover

For the leaks that run the perimeter of the cover, the seals which you cut should provide all the necessary plugging. Ensure there is no way water could pass through, either through a small crevice, crack, or air bubble so that you don’t cause damage further along the line.

Other leaks may require specific fixes, with particular products in mind.

One of the cheapest and easiest ways of fixing leaks from gaps is by using water insulation pipes. These rubber pipes come with a cut along the length, which allows you to unroll it, as well as a strong adhesive.

The flexibility of the rubber will enable you to shape the pipe to the gap, allowing you to cover any possible entrance for water.

Another perk of using water insulation perks is how common and affordable they are. You can find them at just about any supermarket as they are ultimately a piece of shaped rubber.

When small cracks or scratches cause the leaks, the additional role of sealing is best. These often come with the original purchase of the tonneau cover, with refills also being found at any hardware store. Shape the seal to your needs, and with a strong adhesive, patch up the leak.

A pricier but far more protective option is to purchase and use the bed seal kit. These are far more uncommon than the other options; however, it will provide you protection against rain, snow, and dust, with a much easier application to boot.

It offers extra seals and foam blocks, and sometimes a filtration system to purposely drain water out of the way of the bed. Follow the instructions, and you’ll have a waterproof tonneau cover in a few minutes.

Testing the Seals

Your hard work in patching up the leaks will go to waste if you haven’t applied the seals properly. That’s why checking the seals afterward is just as crucial as searching for the leaks. Using the same method as searching for the leaks is perfect for the job, as you are mostly doing the same job.

Running water over the cover will allow you to find new leaks or missed ones and will enable you to test the strength of your patches. Just remember not to apply unnecessary strain that rain never could. Another valid check is to see if light filters through. Being outside or merely turning the lights on will accomplish this test.

Final Thoughts

All tonneau covers leak at some point, regardless of who did the installation. There are three main ways of going about repairing the leaks and preventing the bed of your truck from flooding.

Using a silicone seal, a water insulation pipe or a bed seal kit will all work well in waterproofing your truck. To test for leaks both before and after insulation, sprinkling water over the cover to simulate rain lets you see precisely where the water trickles.

If that doesn’t work, shining a light over the cover will allow you to see whether or not it is completely sealed. Now that you’re confident you’ve sealed your truck bed, you can enjoy the fact that all your goods will be safe and dry while transporting and traveling.

I wrote an article about if tri-folds are waterproof that I think you will find useful.

Soft Folding Tonneau Covers 

With good care and regular maintenance, a soft-folding tonneau cover can last at least five to seven years.

  • Lubricate latches and the locking mechanism every season or more if you live in a harsh environment
  • When cleaning a tonneau cover, use a cleaner and mild soapy water.
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