Black Knight roof sealer
The weather so far this year has not been altogether pleasant. It is disheartening to see the RV sitting in the driveway, but it's raining so hard we really don't want to go anywhere. And remember, all this rain will find a way into your RV and wreak havoc on the interior if there is the slightest leak. Having discovered such a leak in our rig, we were in a bit of a panic to find a sealer. A trip to Home Depot brought a solution in the form of a spray can of Black Knight Roof Sealer.
The beauty of this stuff is that it can be applied to a wet roof. The only drawback is that it is black—but if that is not a problem, it may solve your problem. I suspected the leak was in a seam along the roof vent, so in a light rain I got the ladder out and sprayed this sealer along that seam. It seemed to bubble and froth on contact and run into the suspected crack, then begin to set.
Since then, we have had nearly two weeks of almost continuous rain, but the bed under that vent has remained dry. This product is available in an aerosol can, a caulking cartridge and a one-gallon or five-gallon container.
The spray can cost me $7.29 plus taxes and it did the job. More information on these sealers, go to Home Depot's website and search for Black Knight.