Fixing Leaks in Roof Air Vents on Trailers or RV's - Part 1 - The Seal

If you have a trailer or an RV, you can know that at some point, it WILL leak. They are always moving and with the weather temperature changes, the seals shift during travel and with the air temperature changes as well.

I am not sure what the average length of time the seals on the windows and vents last and I am not sure if they have ever been repaired on my trailer. By the looks of the trailer top vents, I would guess yes.

By the looks on the windows, I would say "no."

About three years ago, I bought a VERY expensive elastic polymer type rubber that you pour or paint on the roof of your trailer or RV to stop leaks. I spent several days cleaning the areas and painting on the sealant. I thought I would have at least five or ten years where I wouldn't have to worry about the roof or leaking.

I was VERY wrong. When I was replacing the seal on the upper sides of the trailer, the rubber paint was cracking and peeling everywhere. I had to chisel it off of the edges so I could get a good seal where I was putting new butyl tape.

The elastic cracked right where the top air vents connected to the roof. We have had lots of rain recently and the cracks were soft and sticky verses the hard seal it should have had. It was such a mess to get off the trailer top and on the edges of the vents.

You can see in the pictures how the rubber white stuff is all around the aluminum edge and on the top of the trailer and on the top of the vent, you can see I didn't take the time to get all the white rubber stuff off or I would be there weeks doing it. My suggestion, DON'T ever use the rubber white stuff if you can help it. Perhaps it is that my roof is aluminum and gets hot and cold making it crack, I don't know but it was so much work to get the vents off to put new tape on.

I am sure it is worth it as the butyl tape seems to last for years as witnessed on the windows of my trailer. 

I used a metal scraper on the roof only and under the edges where scraping the paint won't be an issue. When I used it on the side of the windows and top edges, I had to be careful not to scratch the paint on the sides of the trailer.

The skinnier 1 to 1-1/2 inch scraper is better than the wider 2 1/2 inch I tried, as it didn't get into the edges as well and I scraped the trailer more.

Once you can get to the screws on the top of the vent, unscrew the vent. I used a bucket to keep all the screws in so I didn't have any roll off the top.

Then, put the scraper under the edges all the way around so that you don't bend the aluminum frame on the vent when pulling it up. When I did the first one, I had one of the girls go inside and make sure I didn't need to unscrew anything in there before pulling it up. You don't need to open the vent or anything to get if off.

One thing I did learn on the first one. DON'T set the vent upside down on the plastic lid. If yours is fragile, it may crack. I have lifetime plastic covers that I recently replaced on mine but when I stuck it upside down on the aluminum trailer top, the aluminum left black marks on the top of the plastic lid. This time, I placed it on a roll of paper towels under it before I started scraping the butyl tape off.

I have a bucket where I put all the scraped off tape and garbage. I forgot to line it and the old tape made it a mess. Always line your garbage buckets with a plastic bag for easy clean up.

Scrape off all the old tape and anything else that may have gotten stuck on the edge of the vent and the trailer top.

Once you have scraped it clean, take paper towels or rags and use mineral spirits to clean the edges of the vent where it attaches to the trailer top and the top of the trailer around the screw holes. The cleaner the better.

Make sure when you dispose of the paper towels to put them in an outside garbage so they don't combust in the house. We had friends who had their business burn to the ground due to this. Better safe than sorry.




Once they are clean, place the butyl tape on the bottom of the edges of the vent with one edge right up to the edge of the metal. This will ensure a good seal once you put it down.

I put another piece of tape all around the screw holes on the top of the trailer giving it a double seal. The reason I do this is because the tape that was used to put my trailer together was thicker than the tape you can purchase today. I have had to use a double layer on almost ever seal, especially on the variegated sides that go in and out and aren't smooth. I think they have learned on newer trailers that a smooth side is better than the variegated ones for a good seal.

My battery died about this point in the picture taking so I didn't want to climb down and charge my phone before moving on so I will just let you know the one or two main things left. Before putting the vent down onto the butyl tape, put the four screws through the corner holes on the top of the vent where you would screw them in. Push them through the butyl tape all the way so you have four long screws hanging on the corners. Put one corner in each corner hole at a time making sure the vent doesn't touch the top of the trailer as the sticky tapes will stick and may not be in the right spot. If you have help holding the vent up while you find the corner holes through the tape on the top of the trailer roof, all the better. I just kept poking it around until I got it in the hole. I then hand screwed it in just a bit to hold until I got the other corners in the their holes.

Make sure your vent is on the way you took it off. Usually, the hinge faces towards the front of the trailer as to not blow the cover off if you forget to close it before travel. 

Once the screws are all in the right holes, I used the drill to screw them in half way. I then did the middle hole on each side using the same technique in finding the hole in the top of the trailer and then hand tightening it and then, using the drill to put it in half way. I then did the other holes until they were all in. If one or two of the screws were stripped, (many of the corner screws were stripped for some reason and went round and round without gripping) I purchased some that were an inch longer than the ones that were in the trailer originally and I used the longer screws to secure those holes. It worked every time on the entire trailer but one.

I then tightened all the screws. If there were areas where the metal in between the screws was up high and wasn't sealing well, I took a hammer and hammered that aluminum back down giving it a better stick to the tape.

Because of the rubber stuff around the screws in some areas, I used another layer of the butyl tape and sealed the top of the screws with the tape as well. It will be easier to get off if needed in the future and I can use mineral spirits to soften it when I do. It will be MUCH easier to get off than the rubber paint or silicone as I have had a few spots where the last guy used that and it takes awhile to get that off as well.   I'll post later about how to replace the rubber seal inside the vent and the vent lids.