People often ask us, “Are these tonneau covers waterproof?” Well, the short answer that no manufacturer, that we are aware of, claims their tonneau cover is waterproof. The cover itself, may very well BE waterproof, but since there are many ways for water to get into your truck bed, it is a big thing to make that claim.
Water or snow or dust can enter into your truck bed several ways, even with a tonneau cover on your truck. Some places where moisture can enter include the vertical gaps in your tailgate, or the stake pocket holes, or from the road itself from gaps in the lower part of the bed. All truck beds have holes in them to allow moisture to drain out, but this can also be an area where moisture can enter.
There are some steps one can take in order to minimize chances of moisture entering. The first product is an excellent product by Access, called the TrailSeal:
Access Trail Seal
Access Trailseal seals up your tailgate from the vertical gaps as well as the horizontal hinged area. It only takes about 15-20 minutes to apply the self-adhesive rubber seal. This simple, but ingenious, product will probably solve 80% of the likely areas where moisture can come in.
Another area that has the potential for moisture getting in is the stake pocket holes:
Stake pocket hole
Not every tonneau cover covers the stake pocket holes. In fact, many manufacturers claim this as a benefit, and it IS a benefit if you need access to the stake pocket holes for some aftermarket truck accessories. Thankfully, most newer trucks have plastic caps/plugs that seal the access holes on the inside of the truck bed. In other words, the top remains open, but the access holes on the inside sides are typically plugged from the factory. If your truck has these plugs, then this probably isn’t an issue for you. Some of the older trucks do not have plugs in the access holes, so those holes have the potential to allow rain or snow in. If you can plug them, then you’ve taken care of another place where moisture can enter. We should note that the hard tonneau covers almost always cover the stake pocket holes, so they offer much better protection from the elements than other types of covers.
The final area where moisture can enter (and especially dust or dirt) is through the openings or gaps in the floor of your truck bed. These are there in order to drain out any water that would come in if you don’t have a tonneau cover on your truck bed. They are also there, at times, to allow the truck bed to expand or contract due to wide temperature swings. Typically, if you want to plug these holes, all you need would be is a tube of exterior silicone sealant. This can wear away over time, so you might need to do this every couple of years. A better way to ‘seal up’ these gaps is to get a bed liner. The BedRug truck bed liner is an outstanding bed liner and gives your truck an excellent finished look and also keeps out the water and dust:
BedRug truck bed liner
If you take the above steps, and seal these areas off, you will take care of 99% of the potential for moisture coming into your truck. With this in mind, you may never get any moisture in your truck bed at this point, but it would be a stretch to call your truck bed waterproof. A better term would be ‘weatherproof’ or perhaps ‘weather tight’.