A tonneau cover is an accessory for pickup trucks that covers the truck bed, providing protection from the elements. Tonneau covers come in different styles like roll-up, folding, retractable, and hinged. But they all serve the main functions of shielding cargo from rain, snow, and dust while also improving security and gas mileage.
So why don’t all tonneau covers come with a gasket to make a tight seal against the truck bed? Let’s explore some reasons you may not find a gasket on your particular tonneau.
Is my tonneau cover supposed to be completely watertight?
Not necessarily. Tonneau covers are designed to protect the truck bed and cargo primarily from weather elements like rain, snow, tree sap, and dust. But most are not engineered to be 100% watertight or dust-proof since completely sealing the bed could lead to moisture buildup and rust.
Tonneau covers provide Cover provides substantial shielding without fully sealing the bed. This allows for some natural airflow and drainage while still keeping the bulk of precipitation and debris out. Expecting most tonneau covers to be completely watertight may be an unrealistic expectation.
What tonneau cover styles typically lack gaskets?
Certain styles of tonneau covers are more prone to missing gaskets since they are not intended to make an airtight seal in the first place.
Roll-up tonneaus
Roll-up tonneaus use a vinyl cover that rolls up toward the cab. This style leaves openings at the front, back, and sides of the bed intentionally, making a gasket irrelevant. Gaps allow drainage and flexibility in the roll-up design.
Retractable tonneaus
Retractable tonneaus have rigid vinyl panels that slide into each other. The overlapping panels already provide good coverage without a rubber gasket. Excessive sealing could even cause the panels to stick together.
Hinged tonneaus
Hinged tonneaus have rigid panels that fold open for bed access. Gaskets are not common since hinged panels have some inherent flexibility as they open and close. Foam weather stripping may be used instead to dampen movement.
Could my gasket be missing or damaged?
For tonneau styles designed to seal with a gasket, it is possible for the gasket to have fallen off, worn away, or been incorrectly installed at the factory.
- If your tonneau cover originally had a gasket that is now missing or torn, replacing it can restore the watertight seal. New gasket kits are available through tonneau manufacturers and retailers.
- Make sure to thoroughly clean the truck bed rail andunderside of the tonneau cover so the new gasket adheres properly. Use gasket adhesive for additional staying power.
- Take care not to over-tighten the new gasket which can cause it to crack prematurely. Only moderate pressure is needed to create an effective seal.
Can I add a gasket to my tonneau cover?
If you wish to modify your tonneau cover to be more watertight, it is possible to add certain gasket materials:
Foam weatherstripping
Self-adhesive foam strips can be attached to fill gaps, especially between the tailgate and bed. Compressible foam helps seal out moisture while allowing the tailgate to open freely. Make sure to use exterior-grade foam that won’t degrade in sunlight.
Silicone sealant
Squeeze-out silicone can produce a flexible gasket anywhere larger gaps exist on the tonneau cover. Allow the silicone bead to cure fully before closing the cover. Use an automotive-grade sealant made for metal and exterior use.
Rubber gasket strip
Adhesive-backed EPDM rubber strips can create instant sealing on the tonneau cover edges. Measure the length needed carefully for a custom fit. Self-stick rubber gaskets can seal well but may be difficult to remove later.
Will adding a gasket affect my tonneau cover?
If thinking about adding gasket materials like foam, silicone, or rubber strips, keep these considerations in mind:
- Excessive sealing can lead to moisture and mildew buildup in the truck bed, potentially causing rust over time. Leave some ventilation.
- Thick gasket strips may interfere with rolling or retractable operation. Test that the tonneau can still open smoothly.
- Adhesive-backed gaskets likely cannot be removed without damaging the truck paint or tonneau surface. Use mild foam weatherstripping for easier reversibility.
- Added gaskets can put tension on panels, resulting in cracking, especially with cold weather contraction. Take care not to over-tighten.
- Any damage caused by modifying the tonneau cover may void warranties. Check with the manufacturer first before altering original design.
What are alternatives for better tonneau sealing?
If your current tonneau cover lacks adequate sealing, a few options exist:
Add a truck bed liner
Spray-in or drop-in bed liners protect the entire truck bed from moisture. The textured liner surface also creates a tighter seal with the tonneau cover. Just take care not to puncture or tear the liner when installing the cover.
Upgrade to a premium tonneau
Higher-end tonneaus from brands like BakFlip, Extang, and UnderCover use advanced designs, durable materials, and integrated gaskets to deliver reliable wet and dry sealing. The investment may be worth it for maximum protection.
Use a tonneau cover sealant
Specialized sealants like GB-50 Black Wow act as a gasket-in-a-can to seal leaky tonneau covers, doors, and windows. Just clean, prep, and apply the silicone coating to create a water-tight black finish. Reapply every 6-12 months.
Add a truck bed cap
A fiberglass camper shell creates a rigid, weatherproof compartment over the entire bed. Doors/windows seal tightly while allowing access to cargo and gear. A bed cap offers the ultimate protection for hauling expensive equipment or tools.
Why should I avoid completely sealing my tonneau cover?
While it may be tempting try to make your tonneau cover 100% watertight, there are good reasons to maintain some airflow:
Moisture drainage
Small gaps in the tonneau allow any collected moisture, condensation, or minor leaks to drain from the truck bed. Fully sealing the cover could lead to standing waterinside and rusting if drainage holes clog.
Mildew prevention
Rubber gaskets may form an airtight seal but can also trap humidity and dampness inside the bed. Allowing ventilation reduces chances of mildew growth on cargo or truck components.
Thermal expansion
Severe temperature swings cause metal and fiberglass to expand and contract. Excessive gasket pressure could lead to distortion, cracking, or loosening of the tonneau cover over time.
Easier operation
The more airtight the seal, the harder it becomes to open/close the tonneau, especially in cold weather. Partial sealing is easier to operate daily while still protecting contents.
Warranty concerns
Over-tightening gaskets, using thick sealants, or modifying original hardware could void manufacturer warranties for tonneau covers, truck beds, and associated parts.
What’s the best way to keep my truck bed dry?
For optimal truck bed protection against the elements while avoiding drawbacks of 100% sealing, follow these tips:
- Inspect tonneau gaskets and weather stripping regularly for damage. Replace worn parts promptly.
- Clean the truck bed rails and underside of the tonneau cover before installing gaskets. Proper adhesion prevents leaks.
- Use thin foam strips to lightly seal gaps instead of thick rubber gaskets that could over-compress panels.
- Apply silicone sealant sparingly in small problem areas instead of coating everything. A little goes a long way.
- Ensure proper tonneau clamping during installation. Periodically re-check tension on clamps.
- Park the truck undercover when possible and use a high-quality truck bed cover for daily protection.
- If hauling valuables over long distances, consider adding a secure truck toolbox inside the bed for the best moisture protection.
Conclusion
While many tonneau covers do not come with a complete gasket seal, they still provide excellent protection from the bulk of weather hazards during everyday use. Trying to make your cover 100% watertight could backfire by trapping moisture inside.
With reasonable expectations and proper maintenance, your tonneau cover should reliably shield the truck bed without needing perfect sealing. Special circumstances like cross-country hauling of sensitive cargo may warrant upgrading to a premium sealing cover or adding a bed cap for ultimate peace of mind.
