Are Tonneau Covers Waterproof?

Are Tonneau Covers Waterproof?

One question we are frequently asked is, “Are tonneau covers waterproof”?   The short (but honest) answer is “no”.   They are ALL highly water resistant, but water proof, no.  However, you can get them pretty close to being water tight with a little common sense (and the advantage of our knowledge from installing them for over 20 years in our retail stores).

All of the tonneau covers we sell have some sort of seal or feature (varies by manufacturer and model) on all 4 sides of the cover.  Some have multiple seals in these areas.

Your 2 biggest causes of getting water past your tonneau cover and into the truck bed are rain (duh) and car washes.  Here’s how it gets in and the solution to fixing it

  • Problem –

    • Rain gets in from area that isn’t covered by your tonneau cover, such as around the gap in the tailgate.  Rain normally isn’t an issue since it comes straight down from the sky.  In a thunderstorm with high winds, rain can be almost horizontal, forcing water in
  • Solutions to consider –

    • A tailgate seal covers both sides of the tailgate as well as the gap along the bottom.  These work great and are also very good at keeping dust out.  Driving down the highway and especially dusty roads dust gets in due to the turbulence behind the truck.  These seals install in about 10 minutes using very good, ultra-thin double sided tape.
    • On some trucks the front bulkhead (front of the bed) isn’t completely level with the sides of the bed.  Most trucks are built this way.  Keep in mind that water only needs an opening of about 1 millimeter to sneak in under your tonneau cover. Inspect this area closely before you install your cover to see if you need extra foam in any area
    • If you have a plastic bedliner (drop in bed liner), all of them go over the front rail of the bed.  If you look at the outer edge of front bed rail, you’ll see that the bedliner portion doesn’t quite cover the entire width of the front bed rail, leaving a void for water to get in. Since a tonneau cover will sit on the top of this front “lip” of your truck bed liner, there will be a void where the liner doesn’t meet the side rails.  This is a good place to add a seal.

 

  • Problem –

    • When washing your truck at a car wash (either drive through style wash or do it yourself version) water gets forced in.

 

  • Solutions to consider -

    • When washing it yourself at a high pressure “wand” style car wash, don’t point the wand right at the seal/edge of your tonneau cover.  Hold the wand over your head and shoot it downward so you don’t “force” water in.  At a drive through style, you have no control over the water being aimed right at the edge of your truck bed tonneau cover, and thus your seals.  With this style of wash, there is very little you can do other than make sure your cover is fully “attached”.  By this we mean all snaps are snapped down, cover is fully sealed against the Velcro on the rails, locks locked, etc.

 

When installing your tonneau cover, there is a way to determine where you may get water, but it helps to have a friend here.  After installing your tonno cover, on a sunny day park your truck in the sun and climb into the truck bed with the tonno covering up the bed.  Have your friend close the tailgate, sealing you in the dark.  Look for any area where you may see daylight peeking in.  Remember, water needs less than 1 millimeter to seep into your bed.  It helps to reposition the truck so each side and tailgate of the truck is facing the sun.

 

If keeping your bed dry is one of your biggest concerns, call our experts.  We’ve sold AND INSTALLED tonneau covers, as well as performed troubleshooting on them for over 20 years.  Give our experts a call today at 877-249-8789.

 

 

2 thoughts on “Are Tonneau Covers Waterproof?

  1. My dag gum Honda OEM tonneau leaks like a sieve. Installed by a dealer who I don’t believe had ever installed one before mine. What to do?

    • Capt. Jim – I’ll start off by saying no truck bed cover is waterPROOF, but they are certainly water resistant.

      First thing to check is see if the OEM seals are worn out. any signs of tearing, splitting, small pieces of the seal missing, etc. are signs that it’s time to replace the seals. This is a normal wear and tear item, just like wiper blades.

      Second – install a tailgate seal. We sell these here http://www.thetonneaucoverstore.com/products/detail/extang-maxseal-tailgate-seal

      Third – The easiest way to see where water is coming in is, on a sunny day, crawl into the bed with the cover closed and have someone shut the tailgate (bat stand by to let you out). Once inside the bed and your eyes adjust to the dark, you should be able to see sunlight peeking in through the tiny cracks in several places. Any place you can see even a hint of daylight is where water can certainly get in. It helps to put a piece of tape near this area so it’s easy to find it once you climb out of the bed. In these spots, you might add a small piece of closed cell (non-absorbing) foam or a piece of a rubber tailgate seal.

      Finally, is a water test. Of course you want to do this in warm weather, but get back in the bed and have someone spray the bed with a garden hose. Have them shoot the water into the air so it falls on the cover like rain. This is your best representation of NORMAL water flow. If they are aiming a stream of high pressure water directly at the seals, of course it will be forced into the bed. Foam seals will always lose the battle when faced with high pressure water, like you get at a car wash. Tonneau covers weren’t built to withstand this high pressure. Anyway, doing a simulated water test will help you finalize where the water is actually coming in.

      Good Luck!

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