Silicone

There are other good options, but I use dicor lap sealant for horizontal surfaces (like the roof) because it is designed to settle and spread out a little bit.

On the sides I really like ProFlexRV... it's sticky and stays where you put it.

For seams between surfaces that are out of sight (like a roof) I use Eternabond tape. It's more visible, but it's far more permanent.

Just make sure you have clean surfaces!

I will say that whatever you use, if things are splitting and cracking you will need to stay on it. Check the problem areas twice a year and check everything at least once a year. Visual checks aren't too difficult and preventative maintenance is the best way to keep the water out.

Thanks. Will check out Dicor.

Go to dicor web site and learn where dicor goes and vertical or horizontal surface. Go to youtube and view many vid's on prep and application. Silicone has only a few spots it's good on rv.

Dicor.

I don't/won't use the old clear silicone for anything anymore. It has come loose of everything that I've used it on that's three years or older.

Go to the nearest RV shop and ask them what they're using.

Bill