Raining on your truck cap? Are they waterproof, and how to waterproof yours

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So many companies claim that the truck caps are 100% waterproof, but it’s not the entire truth. The cap can still leak water through the tailgate gaps and other places that provide intrusion. It’s best to buy weather-resistant caps, but there’s no guarantee it will be weatherproof. A new cap may no leak for a while but after a few uses, it can wear out and leak water.

How to Make truck caps waterproof?

There are two ways to make truck caps waterproof. Tool-less and bolting methods. Let’s get to know about these methods.

The bolting method

You have to prepare to make the truck cap waterproof, you have to make sure the tools and material you need are with you. So here are the tools you need for the bolting method.

  • An electric or manual screwdriver
  • An electric drill machine with different types of bits
  • Truck bed installation tape
  • Washers or bolts
  • A large blanket made of thick fabric, to protect the cap from scratches and damage.
  • Aluminum hardware G clamp
  • 3/8 inches threading and 1.5-inch bolts.
  • Although you can do this task all by yourself, it will be best if you hire help.

To use this method, you have to follow these steps:

  1. Remove the cap from the truck according to the ways it was installed. Avoid laying the item on the ground because it can scratch and damage the material.
  2. Flip the cap upside down and apply the tape across the material. Make sure to apply the cap carefully, and add extra layers to cover the large gaps.
  3. On the other hand, some parts must not have tape covers, like the rear hatch. This way you can use the tailgate.
  4. You have to flip the cap to the original position and make sure it fits evenly and properly. After this get inside the bed and you have to use two aluminum G clamps to attach the truck bed rail.
  5. If the truck already has damage and holes, you can add the bolts and nuts to hold it straight.
  6. If the truck cap has no holes, you have to drill three to four holes on the truck bed edges. After that use the nuts and bolts and screwdrivers to attach the cap in the right place.
  7. Lastly, for the bolting method, you have to check the taillights. Find the brake wiring of the taillights and make a hole in them. This way you can strip the cover and attach it with the high mount brake.

The tool-less method

This is another method you can use to make the cap waterproof. This is a great method that requires no tools in the procedure. This is a great solution for individuals who are not experts in handling manual or electric tools.

  • The tools you need for this method: Gather the materials you need for the task. You have to use things such as RTV silicone sealant, Rubber weather insulation tape, Industrial degreaser.
  • Clean and prepare the connection point: You have to apply the degreasing solution on the joint of the cap and the truck bed. Make sure to clean the debris and dirt from the area. You also have to scrape off the previously applied glue or weather stripping from both parts. Cleaning the rail and the connection point will make your work easier.
  • Apply weather stripping material: Next, you have to apply a good amount of glue to the cap, and carefully align the rubber weather strip over it. Make sure to apply glue quickly otherwise it will dry up before attaching it to the rails. This will make the work strong and the cap will last long. You can apply the weather stripping on the built-in windows and doors using the same methods.
  • Apply extra coat: If you are not using a drill, then it’s important to use an extra coat of insulation. RTV silicone is the best product for this. After applying it, you have to leave it for drying, then use a garden pipe to test the efficiency of the waterproofing method. This way you can identify the leakage points and then apply another layer of insulation over the cap.

Check these two methods to waterproof your truck caps. Even if you are not well-versed with tools, you can check out the second method.

Frequently Asked Questions

Can I store my truck cap on its end?

It is never recommended to store your truck cap (when it isn’t on the vehicle) on its end. This can cause it to warp, and possibly no longer work on your truck! Another downside, is the fact that it could fall over and get damaged, or worse yet hurt someone.

Do truck bed covers lock?

Many bed covers out there today will lock! However you should make sure to check the specifications of the version you are buying before purchase.

What is the cover for a truck bed called?

The cover for a back of the truck can be a couple different things! Bed caps make an expansive storage container on the back of your truck, a tonneau cover is a flat cover to keep water and people into the back of your truck, and a bed rack is for setting things on the rack without taking space from the inside of the bed itself.


The waterproofing methods at the end of this article can be great solutions for truck caps that are not waterproof yet. The waterproofing method using tape is very simple and there’s no need to spend much money on tools, and you have to repeat it when needed.

The first waterproofing tool will probably stop your truck cap from water leaks, but if sealed correctly it will last longer without needing further waterproofing.