How to fix a leaking tonneau cover: a detailed answer

Tonneau covers are an essential and useful part of cars, as they help to protect your cargo bed against rain and snow. Meanwhile, there is no one hundred percent guarantee that your tonneau cover won’t leak.

leaking tonneau cover

A leaking tonneau cover: reasons

A cargo bed provides car owners with so many advantages. There is plenty of space, and that is very convenient.

At the same time, you may suffer from other problems concerning this cargo bed and the cover.

What are they? Your cover may start leaking.

The key reasons for it may include the following:

  1. there is a gap between the bed rail and the edge of the cover;
  2. there is a tear in the cover;
  3. weather stripping of the truck isn’t being replaced for a long time;
  4. the old sealant, which you have to replace.

As we can see, there is a variety of reasons. As for the consequences, leaking water can cause rust or your cargo to get wet. It is extremely inconvenient and harmful. Therefore, tonneau covers have to be checked regularly and fixed if it is needed.

How to fix a leaking tonneau cover yourself? What tools do I need? Can I avoid seeking a professional? In this article, we provided all the answers you need. Let’s start!

How to fix a leaking tonneau cover: a detailed guide

In general, if your tonneau cover leaks, it is possible to fix it yourself. Otherwise, you still can go to a professional in case of not feel sure that you can do it yourself. Note that if you choose the first option, you still need somebody’s help.

Fixing your tonneau cover, there are several tools that you need:

  • a garden hose/a car wash,
  • a cardboard/a newspaper,
  • a measuring tape,
  • silicone or seal strips.

Let’s consider the main steps which should be taken when you want to fix a tonneau cover. They include the following:

First of all, close a tonneau cover, but not a tailgate. Thus, you will be able to understand the source of the leak. Now you are ready for spot detection.

As we have already mentioned, in this process you require somebody’s help. Call your friend or your family member, so they could help you with the next step. For this step, you also need a garden hose or a car wash. Now it is time for the rain simulation.

Your helper has to use a hose to simulate rain. Note that water must be sprayed upwards (just like rain usually does). Now, when the water falls over the tonneau cover, it is possible to examine your pickup truck.

The next step provides two options, so you may choose any of them. The first one includes using cardboard or a newspaper (they will serve as an absorbent material) to put them on the cargo bed. Completely cover it. Thus, you will be able to see where the exact wet patches where it is leaking and fix the problem.

Another option is using a flashlight (for example, your phone’s). It will help to look inside the truck bed and find out the source of the problem. After you find the leakage’s source, it is time for the next step.

By the way, don’t forget to mark these leaking spots with a pen or tape, so you will be able to find and fix them later.

It would be better if you have a measuring tape, so you know the exact area of the tonneau cover which has to be fixed. Remove the cover completely, as the leaking is located between the tonneau cover and the panel of the truck.

If the perimeter of the cover leaks, it is better to use silicone or seal strips. They are quite effective and safe. Multiple leaks can be fixed by lining the entire cover, so there would be no need to deal with this issue later.

In case of a leak at the body of your cover, it is also the silicone that helps to solve the problem. Even duct tape could help in such a situation.

As we are done with fixing, we can move to the testing. Firstly, repeat this sprinkling water step to check there are no leaks left. Is your tonneau cover leaking?

Then you have to try following the guideline mentioned above one more time.

Does your cargo bed still have leaking spots? Well, the reason may be the fiberglass paneling. Then it is time to go to a real professional. In this situation, such things as a hardening solution, polyester resin, and a cloth will be needed.

We have finished! Now your tonneau cover is fixed, and your vehicle is ready for the next trips.

Other ways to fix the leaks

There are still some more ways for dealing with the problem which we haven’t mentioned but they still deserve attention.

Water pipe insulation. This method of insulating water pipes is very efficient, easy, and not expensive. To start with, buy water pipe insulation at the store. Water-resistant vinyl is the best choice because it effectively removes any breaks or/and leaks.

Tonneau covers can be fitted with adhesives and slits at the sides, and a bottom seal can cover the leaks. What you need to do is to place them around a leaking area or at the gaps.

Covering the cargo bed, you will see that the covers have a secure seal.

Bed seal kit. One more effective and fast method is installing a bed seal kit. One of its main advantages is that it protects you not only from rain and snow but also from dust. In addition, it also keeps the cargo bed conditioned.

Though the price may be higher, it is worth it. It should be added that some of the kits sometimes include a drainage system that won’t let water gather behind the truck.

Extra seals. They are quite affordable and efficient. It is the best and easiest solution if there are not many leaks. It is important to choose the right size for the leak. In addition to the mentioned above, you may use various materials for added protection.


Let’s summarize the main questions which may occur concerning a leaking tonneau cover. Here comes a list of these questions and answers to them:

Why does my bed cover leak?

The reasons for the leak vary from gaps and tears to worn-out weather stripping and sealant. Moreover, it may happen while your car is being washed. In the first situation, you have to cover the gaps between the tonneau covers and the top of the bed rails.

Using plastic, metal clip-on panels, as well as a cloth tape, will be appropriate.

Do all tonneau covers leak?

The most common problem that car owners face is when their tonneau cover leaks. Rainfall often causes this unpleasant result. Don’t get upset, there are plenty of ways how to deal with this issue fastly and efficiently.

How do you make a tonneau cover watertight?

In addition to the guideline above, it is a tailgate seal that may help to solve the problem with your cover. A tailgate cover seal will help to cover the gap along the bottom, as well as the sides of the tailgate. Moreover, it prevents dust from letting in.

How do you seal a truck bed cover?

You may use any preferred material for covering up the leaks, as there is a great variety of materials appropriate for this process. If there is a minimum of leaks, use additional seals, which are not expensive but very efficient.

Final recommendations

Now you know how to fix a leaking tonneau cover and keep your materials and truck bed safe and dry. Though it is not quite an easy process, you still manage to do it yourself.

Note that you still can try to change your tonneau cover in case of having a warranty. As we all know, sometimes professional help is inevitable.

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