How to Waterproof Your Truck Cap: 2 Effective Methods


truck camper shell

Your truck cap or camper shell is one of the greatest assets of having a truck. Not only does it protect your gear from them, but you can also turn your truck into an RV using one, allowing you to enjoy the weekend out exploring with the family.

However, if your truck cap is your camping shelter, you should make sure that the truck bed stays dry and safe from rainwater as well as dust and other elements of weather.

That’s where this article comes in to help you! Today, I’ll walk you through a complete guide on how to waterproof your truck cap using various methods that work. So without further ado, let’s jump right in!

Method #1: The Bolting Method

1. Prepare What You’ll Need for the Method

Before starting with the steps of the waterproofing process, you should make sure that all the tools and materials needed for the job are there. So here are all the tools and materials that you’re going to use for this method:

  • Electric drill machine with different sizes of drill bits
  • A manual or electric screwdriver
  • A large blanket or some fabrics thick enough to protect the truck cap from damage and scratches as you work on it
  • Truck bed insulation tape
  • 1.5 inches bolts and 3/8 inches threading
  • 3/8 inches locking nuts
  • Washers for bolts
  • Aluminum hardware G Clamp

Although you can get the job done on your own, it’d be much easier and more convenient to have someone to help you throughout the process, so make sure that you can find a helping hand as well.

2. Lay Out the Truck Cap Ready

The first step to insulate the truck is by removing it from your truck by unscrewing it according to how it was installed. 

Avoid laying the cap on the floor directly because it’ll scratch and damage the cap. Instead, spread out some sheets or a large blanket and put the truck on it upside down so you can work it out.

3. Apply Insulation Tape on the Truck Cap

With the truck cap flipped upside down, apply the insulation tape across the truck cap. Make sure that you apply the insulating tape carefully and add more layers of insulating tape where there’s a larger gap.

For example, the bulkhead area might need up to 3 layers of insulating tape to completely seal it against water leaks.

On the other hand, some parts shouldn’t be covered with the tap, such as the rear hatch, so you can use the tailgate freely.

4. Fit the Cap Over the Truck Bed

Flip the cap back to its original position and place it carefully over the truck bed and make sure that it sits properly and evenly.

After that get inside the truck bed and use the 2 aluminum G clamps to secure the truck bed rail to the cap.

If your truck cap already has holes for installation, simply apply the nuts and bolts to hold it in place. 

If it has no holes, drill 3 to 4 holes across the truck bed rail, in which they’re about 30 inches apart from each other. After that, use the bolts, nuts, and washers to secure the truck cap in place with a screwdriver.

5. Check the Taillights

Locate the brake wiring of the taillights and make an incision in it, so you can strip the case and connect the high mount brake light wire.

Here’s a quick video tutorial that shows you how to do it the right way.

how to waterproof truck camper shell

Method #2: The Tool-less Method

What’s great about this method is that it uses almost no tools in the process. Which makes it a great solution for someone with no experience with power tools like drill machines. Here’s how to pull it off:

1. Gather the Needed Materials for the Job

Since you use no tools for the process, you’ll need some extra materials for insulation so that you can glue the insulation rather than drilling it. Here’s what you’re going to need:

  • Rubber weather insulation tape
  • Industrial degreaser
  • RTV silicone sealant

2. Clean and Prepare the Point of Connection

Apply the degreasing solution on the part where the truck bed and cap meet on the rail and make sure that all dirt and debris are removed from the surface. You should also scrape off any previously applied weather stripping or glue on both side

3. Apply the Weather Stripping

Apply a generous amount of glue on the truck cap and carefully align the rubber weather stripping across it. Make sure you do that quickly so that the glue doesn’t dry up before fixing it on the rails.

You should apply the weather stripping on all built-in doors and windows as well using the same method.

4. Apply Extra Coat of Insulation

To make up for the lack of drilling, you’ll need to apply an extra coat of insulation using RTV Silicone.

Wait for the glue to completely dry, then use a garden hose to test out the efficiency of the waterproofing. Locate any points of leakage and apply a thin layer of RTV silicone over it.

Wrap Up

With that said, you now know how to waterproof your truck cap in a variety of ways. As you can see, the two methods are pretty easy and don’t require a lot of DIY skills or thorough experience with hardware tools.

However, both of them would be much easier to achieve if you seek someone’s help, especially while removing and putting the truck cap back on.

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