Do you want to put a truck cap on your pickup truck but already have a tonneau cover installed? This is a common question for truck owners looking to add more storage and protection. The good news is that it is often possible to mount a truck cap over an existing tonneau cover. Here are some tips to help you do it right.
What is a Tonneau Cover and a Truck Cap?
First, let’s go over what a tonneau cover and truck cap are.
What is a Tonneau Cover?
A tonneau cover is an accessory that goes in the bed of your pickup truck. It covers and protects the truck bed. Tonneau covers come in different styles:
- Soft roll-up covers
- Folding covers
- Retractable covers
- Hard folding covers
- Hard solid covers
The most common type is a soft roll-up tonneau cover. These use vinyl or canvas over an aluminum frame. They roll up to give you full access to your truck bed.
What is a Truck Cap?
A truck cap is a fiberglass shell that sits over the bed of your pickup truck. Truck caps are also called truck bed caps or camper shells. They turn your truck bed into a large storage space. Truck caps protect your gear from the weather. Most truck caps have locking rear doors for access.
Why Would You Want Both on Your Truck?
So why would you want to put a truck cap on if you already have a tonneau cover? Here are some reasons:
- Extra protection – The truck cap encloses the sides and top of the bed. This gives more security and shelter.
- Added storage – Truck caps maximize the usable space for hauling and storage.
- Custom look – Some people like the style of a truck cap/tonneau cover combo.
- Camping use – Truck caps can be used for camping trips. You can sleep inside a truck cap.
- Versatility – It allows you to keep the benefits of both accessories.
What Do You Need to Know Before Installing a Truck Cap Over a Tonneau Cover?
Installing a truck cap over an existing tonneau cover is possible in many cases. But there are some things to keep in mind:
Will They Physically Fit Together?
- Make sure the truck cap you want will be tall enough to clear over the tonneau cover. Measure first to confirm.
- The tonneau cover also can’t stick up too high. It needs to leave room for the cap to clamp to the bed sides.
- Hard folding covers and soft roll-ups usually work best. Higher profile covers may not be compatible.
Is Your Tonneau Cover Removable?
- Some tonneau covers can be easily removed. Check if yours can be taken off if needed.
- Removable covers allow you to take it off to install the truck cap. Then you can put it back afterward.
- Non-removable covers will have to stay on under the truck cap permanently. Make sure they will fit together properly.
Do You Need to Modify the Tonneau Cover?
- You may need to trim or modify your tonneau cover to make it work with the truck cap.
- For example, you may need to cut away any parts that stick up too high and prevent the cap from fitting.
- Only modify the cover if permitted by the manufacturer. Do this at your own risk.
Step-by-Step Instructions for Installing a Truck Cap Over a Tonneau Cover
Once you know your truck cap and tonneau cover are compatible, here are the basic installation steps:
Step 1: Remove the Tonneau Cover (If Possible)
- If your tonneau cover can be fully removed, take it off by following the manufacturer’s instructions.
- This will give you a clean truck bed to install the truck cap.
- If your cover is not removable, skip this step and leave it installed.
Step 2: Clean and Prepare the Truck Bed
- Give your truck bed a thorough cleaning before installing the cap.
- Remove any debris, dirt, or rust. Wipe away moisture or oil.
- The bed should be as clean and dry as possible for best adhesion.
Step 3: Position the Truck Cap on the Bed
- With at least one helper, lift up the truck cap and center it on the bed.
- Align it evenly from side to side and front to back.
- Adjust the position until it sits flush and square on the bed.
Step 4: Clamp the Truck Cap Securely Into Place
- Using the provided hardware, tighten the clamps according to the manufacturer’s guide.
- This secures the cap firmly to the bed.
- Go around and check each clamp is tightened properly. Do not overtighten.
Step 5: Reinstall Tonneau Cover (If Removed Before)
- If you took off the tonneau cover in Step 1, now replace it.
- Follow the exact reverse steps to put it back on the bed under the truck cap.
- Refer to the cover manufacturer’s instructions for proper reinstallation.
Step 6: Seal and Weatherproof All Seams
- Seal any gaps between the truck cap and bed with weatherstripping or caulk.
- This prevents dust, water, and noise from entering.
- Pay special attention to sealing around the tailgate for maximum weather protection.
Step 7: Check All Mounting Points
- Do a final check that the truck cap is securely mounted with no gaps, spaces, or instability.
- Ensure all clamps are tightened to the specified torque.
- Make sure the tonneau cover is also correctly reinstalled as needed.
Tips for Mounting a Truck Cap Over a Tonneau Cover
Here are some additional tips to help make the installation go smoothly:
- Have at least two strong people to lift up the truck cap – it can be heavy and unwieldy.
- Use painter’s tape to hold any loose wiring or parts out of the way during installation.
- Keep the truck cap centered as you lower it to avoid scraping the cab or bed sides.
- Follow all safety practices – wear gloves, secure long hair, use helpers, etc.
- Install the clamps a little at a time in a criss-cross pattern to evenly compress the seal.
- Park on level ground and use wheel chocks to prevent any rolling or shifting.
- Refer to the manufacturers’ instructions for torque specs and guidelines specific to your models.
Potential Issues When Mounting a Cap Over a Tonneau Cover
While it is possible to mount many truck caps over tonneau covers, there are some potential issues to be aware of:
Limited Access to the Truck Bed
- With both a truck cap and tonneau cover, access to the bed is restricted compared to just having one or the other.
- The tonneau cover may block access from the truck cap door. Evaluate if this will work for how you use your truck.
Reduced Truck Cap Security
- Truck caps are normally locked directly to the bed for security.
- Having a tonneau cover underneath may allow more access by loosening clamps.
- Use high-quality locks and clamps to deter break-ins. Or remove tonneau cover first.
Possible Mounting Interference
- If the tonneau cover sits too high, it can interfere with properly clamping the cap.
- There may be limited contact with the bed sides, reducing stability.
- Carefully check for any gaps, spaces, or instability after installing.
Potential Moisture and Dust Buildup
- Sealing the truck cap to the tonneau cover instead of the bed may allow more water and dust to enter.
- Pay extra attention to weatherproofing all seams as best as possible.
- Periodically check under the cap for any moisture buildup.
Conclusion
Installing a truck cap over an existing tonneau cover is doable in many cases with proper planning and preparation. Measure first to ensure fitment. Consider if bed access and security are concerns for your needs.
Follow all manufacturer’s instructions closely, seal thoroughly, and inspect the finished installation. With care and patience, you can successfully combine the benefits of both a tonneau cover and truck cap on your pickup truck.
