February 5, 2018
One of the first questions we get from our customers who are interested in a tonneau cover is, “Are tonneau covers watertight?”, “Is this thing waterproof?”, or something similar. The short answer to this question is, when properly installed, a tonneau cover will keep the vast majority of water from entering your truck’s bed. To describe a tonneau cover as 100% watertight or waterproof would be inaccurate, but the most you’ll usually get are a few drops intruding during a rainstorm. A detailed explanation will give you a better idea of how much weather protection you can expect when you install a tonneau cover.
There are several different tonneau cover designs available on the market including soft and hard covers that open in a variety of different ways. Often times, the design of a tonneau cover will dictate the amount of water resistance you can expect. In the section below, we’ll examine and rank the water resistance of the most popular tonneau cover designs.
If your number one priority is keeping as much water out of the bed as you possibly can, a painted one-piece cover is the design you want. This cover consists of a single piece of fiberglass or ABS plastic that covers your bed from front to back, usually overlapping the tailgate and bed rails. This leaves the rear hinge as the only likely area where a small amount of water might intrude. UnderCover also offers gloss black versions of this cover design that are more affordable than comparable painted covers.
Three tonneau cover categories fall under this level of water protection: retractable, hard-folding, and hard roll-up covers. While they offer similar levels of water resistance, there are several key differences between these three categories.
Retractable - Retractable tonneau covers roll out from a canister that mounts at your truck’s bulkhead. The materials used can vary from aluminum to padded polymers and polypropylene, but the basic design remains the same. The rails on a retractable cover are often designed to channel water toward the bulkhead and out through hoses that attach to your bed’s drainage ports. They also use compression seals at the tailgate to prevent excess water intrusion at this otherwise vulnerable area.
Hard Roll-Up - While there aren’t many covers in this category, they do deserve special mention. Using vinyl or canvas lining over a series of interlocking aluminum panels, these covers combine the security of a hard cover with the look of a soft roll-up. The panels and vinyl overlay work together to create a cover that keeps the majority of water out of your truck’s bed.
Hard-Folding - A hard folding tonneau cover consists of aluminum, FRP, or thermoplastic panels that fold back to allow bed access. Hard folding covers are popular because many of them allow near-total bed access when opened and can be removed easily to make room for large cargo. When installed correctly, this design affords a good balance of water resistance and utility. Some hard folding designs like the BAKFlip VP incorporate a vinyl lining across the top of the cover that further improves water resistance.
This level of water resistance contains two tonneau cover categories: soft roll-up and soft folding.
Soft Folding - This cover design consists of a vinyl or canvas tarp mounted on a folding one-piece aluminum frame. It is one of the easiest covers to install, usually requiring no tools, just hand-tightened clamps that attach to your truck’s bed rails. Since it sits on top of your truck’s bed rails, most water will flow down the sides of your truck, though water can seep in at the hinges in some cases.
Soft Roll-Up - This tonneau cover opens by rolling towards the back of your truck's bed.
One of the oldest tonneau cover designs, snap covers use snaps to fasten to a rail that surrounds your truck bed. Since snap covers prioritize affordability over all other qualities, these covers tend to be less watertight than other designs, particularly in heavy and windy storms.
There are many benefits to installing a tonneau cover, and they vary with each model. If you need help measuring your truck bed, check out our helpful article or give our product experts a call at 877-216-5446.