Thursday, May 3, 2012

Water is Evil. How to Find and Fix RV Vent Leaks - Part.2

Well, Passenger Pete and I tackled the repair of the leaking roof vents recently. Mostly it went well. Of course there were the unavoidable....(Well, OK they could have been avoided if I hadn't been so eager to get the job done before it rained!) issues.

Scraping Begins
First, we began by scraping the existing caulk so it was mostly flat and removing the goop from all the screw heads. It is CRITICAL you get all the silicone (new and old) removed. The tape will NOT stick to silicone and you will not get a watertight seal!

Next, I removed the screws from one side at a time to check for damage and how tight they were. For some of them I placed a dab of wood putty in the hole (below the plastic) before replacing the screw. I figured the tape would hold everything together, but why take chances!

Bad Crack Number #1
Some of the cracks in the caulk had been sealed (by me) with the same paralastic adhesive we used to adhere the Solar Panels to the roof in a previous project. No silicone in that stuff, so it was okay. There were some places that the cracks were VERY bad, you could see into the roof structure if you squinted enough.

We made sure that those were as flat as we could make them with a scraper and a razor blade. You know me, always paranoid and a bit of a perfectionist! Better safe than sorry when it comes to roof leaks in your RV. Water will destroy so many things if left unattended. I'm still thinking about adding some expanding foam to the sections of the roof that allowed the water to seep from the crack all the way out to the edges of the interior.

A reader recommended a product that would prevent additional damage to the wood that had already gotten wet. That's probably a good idea as well.

My roof is fiberglass, so I used soap and water to do the basic cleaning of the areas that the tape would be applied to. After that a scrub down with isopropyl alcohol to prep the surface. If there was any oxidation, we made sure it was all removed with those cleaning steps.

Now the sticky part. I had a 50 foot roll of 4" wide tape to work with. It came wrapped in shrink plastic. Once removed, there were waxed(?) plastic disks on either side of the roll. These are important! I read a forum message someplace that someone had permanently affixed the entire roll flat on their roof! I really didn't want that to happen! I tried to make sure the roll was put CAREFULLY back on the disk or stood up vertically in a safe spot. yes, there were some tense moments....but no disasters. This time!

First Cut piece of Tape
By partially unrolling the tape upside down, we were able to measure and cut each piece. I used an inexpensive pair of "miracle scissors" like the ones Paramedics use for bandages. They work GREAT. You know, you can even cut pennies in half with them, but you shouldn't because the Federal Government frowns on that sort of thing.

Once measured and cut, we flipped the tape over and took a look. So far so good! You have to be careful of the edge of the tape as the sticky stuff is squeezed between two pieces of plastic and has oozed out a bit making the whole edge sticky. Believe me, it WILL stick to almost anything and the gooey residue is hard to remove. Mark where you want the tape to be, we used blue painters tape.

One Side Done!
The trick to removing the backing on the tape is to hold it in both hands, between thumb and forefinger and vigorously "waggle" it back and forth. This releases the backing at the top edge and makes it easy to remove. ONLY remove a couple of inches!!!! This stuff will stick to almost anything, especially itself! Better to have only a couple of inches to work with. Flip the tape, sticky side down (DUH!) then affix it next to the previously set tape marks. Pull the plastic backing slowly back toward the other end while gently pressing the tape to the surface. Make sure you have the inside edge lined up against the vent. I hate crooked seams! Rub the tape down so it forms over and around all the bumps and imperfections underneath it. You can use a small wallpaper roller if you like. Try and eliminate as much of the air bubbles and creases that you can for a smooth professional appearance.

Three Sides Done
Repeat for the other three sides. I left the side with the hinge for last as it was going to require trimming the tape the long way. At each side we went back over the previous ones to further smooth out the bumps and make sure it was tacked down all the way around. Especially at the seams where the tape overlaps. You can choose which order to do these, since you may want a different pattern for the overlaps.

The Hinge
And now for the hinge side. As you can see by the photo, this one was pretty gunked up and needed some special attention. After it was cleaned and prepped, it didn't look all that much better! One of the nice things about a 4" piece of tape is that it will cover a lot of visual evils! One of the roof vents only had to be trimmed along one edge (near the solar panel), but the other had to have 1"+ removed to make it fit. This wasn't super hard to do, but my ability to cut a straight line isn't so great to start with. I'll spare you the photo of that crooked mess!

Finally, the first vent was completed. there was some residue from where the glue bled out of the seams. I will have to figure out how to remove it...mainly because it looks bad. The other vent had much more trimming to do, but since we'd already done one it took about the same amount of time. We also did the flanges on my slowly dying shower skylight. this was a much bigger job and every side had its problems. I am pretty sure no one else will have those sorts of odd Aero Cruiser issues. if you do, let me know I've already suffered through THAT fix.

One Of The Round Roof Vents
All that's left were the round vents for the bath, stove, water heater, tanks, etc. Those are all round. I've managed to get one of them done. It looks OK, not great, but OK. I left the bonding tape square around the outside edge since I couldn't manage a true round cut. Ah well...better it works well than looks good!  At some point I will figure out how to remove the tape residue.....

I'm going to practice my scissor work before the other ones get done get tackled. Besides, they're not leaking....YET!

Be Seeing You...Down The Road,

Rich "The Wanderman"

See Part 1: Click Here!


  1. Great article. Tell me, what is the name of the tape you used and where do you buy it?

    1. Anonymous,
      Thanks! There are a few brands of roof sealing tape available. I used Eternabond 4".


      Rich "The Wanderman"

  2. I did the same think with a fantastic fan. Maybe not a good idea, I had to replace it later and that tape was impossible to remove.

  3. Paul,
    While the tape is difficult to remove, with the right solvent (One that WON'T damage your roof material) it is removable. Not easy, but do-able.

    Rich "The Wanderman"


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