How to water proof tailgate?

putting a tonneau cover on this weekend. I notice when I'm driving I can see daylight between the sides of the tailgate. Should I have any concern of water intrusion from those places under normal use? Probably worse case would be a car wash scenario or driving in very heavy rain.

Is it something I could just add weather stripping to the sides?

 

Not likely. Maybe in a car wash, but on my dad's truck, there's at least a 1/4" gap between the top of the tailgate and the tonneau cover, and we never have water getting in (other than the car wash).

 

factory cover, never had any issues with water in the bed

 

Same, have a truxedo on mine. Added a lund tailgate seal for dust while hunting and dirt roads, but honestly it was just for fun. Before the seal I never ever had any water or sand in the bed with the tonneau closed.

 

I wouldn't count on any Tonneau cover being water proof. They'll all leak eventually.
But what you will find very beneficial is that you virtually turn your truck bed into a huge trunk.

Leave things there without concern of being stolen easily.
Leave things and not worry they will fly out.
Protect things from the sun.
Easy to remove for full bed access.

I have the Extang SolidFold 2.0. Worked great on my trip from Los Angeles to Denver (1100 miles).
I caught sun, rain, snow. Luggage/merchandise was 98% dry. Only wet portions where close to the
edges due to water running along the edges. Its only water, so I didn't mind.

Edit: I had a friend stand in the center of the thing, he weighs 200 lbs.
More than I expected in terms of rigidity.

 

Besides sealing the tailgate, you may have water intrusion from both front corners of the bed, but you can stuff some foam there to stop intrusion and it will help a lot.
But as been said don't count on a 100% dry bed 100% of the time, the sides may get some drops, but you'll do good in the middle.

Hope that helps
Cheers!

 

You will get tons of water leaking in through those front two corners in anything resembling a rain. I'm talking buckets. Go to Home Depot, get a butyl-based Asphalt Sealant, and fill those gaps in. You also need to take off the head rail and seal all of its openings (even the ones with plastic caps on them) with the same sealant.

For the tailgate you can get a tailgate gasket from Amazon, which will eliminate the leaks through the bottom, but the top parts of the sides of the gate will still let in water and dust - not much you can reasonably do about that.

 

OP - you failed to mention what cover you're installing.

 

Sorry guys... It's the undercover lux se cover. It looks like it completely hangs over the bed rails and tailgate so no water can come in from the top or sides of the rails or gate. Iffy on how it will seal towards the cab but it looks like that will be ok and I'm not too worried about water coming from beneath the truck. And I don't need to keep electronics or anything that special (at least without being in another container ) but do want to be free to put luggage or golf clubs back there without worry.

 

A one piece tonneau cover like the one you have will do a much better job keeping your bed dry than most of the other style covers. I have the fold-a-cover G4 hard folding cover and it does come with a tail gate seal but I haven't installed it yet and so far the bed has stayed dry.