Advice on re-sealing a leaky roof vent?

[Rich W.]

I have a very small leak somewhere around my kitchen vent. I’ve found a small amount of water on the floor a couple times, about equal to a melted ice cube, and never made the connection to a leaky roof vent until we spent some time on the North Coast in heavy rain for several days. Then it became obvious. A small but steady drip from the vent. Light rain doesn't make it leak into the coach - I guess the insulation has been soaking it up for the most part.

I removed the decorative wood grill and the plastic interior surround during a nice heavy rain, found a lot of wet insulation, and was able to watch water slowly leaking in on the front edge of the vent housing. So I know where the leak is. I removed the wet insulation (thankfully no mold or mildew) and have been waiting to do the repair until I had a week or so of sunny weather so I know its dry inside and out.

What I don’t know is whether I should try to remove the generous portion of factory sealant first, or just add to it around the edges hoping that gets it. I don’t know how I would mimic the factory sealant job so removing and re-doing it wouldn’t look the same but it would probably work. Another option is paint the entire seal area with rubberized RV roof paint - I have some of that on hand as well as a couple tubes of dicor.

So the big question: What would you do?

 

[Jim]

What I don’t know is whether I should try to remove the generous portion of factory sealant first, or just add to it around the edges hoping that gets it.

To be honest Rich, I really don't know what you would gain by removing the original sealant. I've had this same issue on both of my previous motor homes, and I've always had good results by cleaning the area well, and then apply a generous amount of Dicor self leveling sealant. That seems pretty much the standard for situations like these.

 

[Rich W.]

To be honest Rich, I really don't know what you would gain by removing the original sealant. I've had this same issue on both of my previous motor homes, and I've always had good results by cleaning the area well, and then apply a generous amount of Dicor self leveling sealant. That seems pretty much the standard for situations like these.

thats what I wanted to hear. The boss suggested that if the original sealant was drying out it could have a hairline crack that I might not see, but this seems unlikely. And if my attempt at patching up the existing seal doesnt work, I can take more drastic measure then. Also I’m working up a Mother Ship list so they can do a professional re-do while addressing other stuff.

 

[Neemer]

@Rich W. , i would just caution to ensure you determine the type of sealant used by the factory. Newmar used a silicone sealant on mine, and dicor will not stick to it. If yours is the same, nuflex would be a compatible sealant.

 

[Rich W.]

Good info and an excuse to procrastinate one more day so I can check with Newmar. Thanks!

 

[lostinfla]

It's not that big a deal to remove the old sealant and re-do it. I did the entire roof (all penetration's) a couple years ago with the wife's help and it's really not that bad. I have replaced all three fans with Maxair units and they are just sealed with butyl tape and screws when installed and finished with Dicor on top. Shouldn't take more than a half hour to completely reseal one vent.

 

[Rich W.]

It's not that big a deal to remove the old sealant and re-do it. I did the entire roof (all penetration's) a couple years ago with the wife's help and it's really not that bad. I have replaced all three fans with Maxair units and they are just sealed with butyl tape and screws when installed and finished with Dicor on top. Shouldn't take more than a half hour to completely reseal one vent.

I think that’s what I’ll do. I hate to keep piling up more sealant. And then I guess I should progress on to the rest of them like you did. Six years old and if one is failing the rest are probably not far behind. I know I can do a nice effective, clean job of it, bit it wont look like the factory job. Maybe thats not a bad thing.

 

[Rich W.]

I think this is what you’d call a clue. I removed all of the old stuff and re-sealed it, so it should be fine, but it looks like all the rest of the penetrations aren’t far behind. We are scheduled for a heavy rain starting tomorrow night so it will get a good testing.

 

[Rich W.]

I guess I need to pay closer attention to my roof. I was up there a lot last summer with the new AC install, cleaning and treating the fiberglass, and cleaning the solar panels, but missed this and it doesn’t look like a new condition.

This coach came from Arizona and while it only had 17k miles, and was in new condition inside, it was four years old and probably spent all that time outside exposed to the Arizona sun. The clear coat had failed on the top of the end caps and the painted radius portions of the roof along the sides, the tires were starting to get sidewall cracks, especially on the divers side, and now this.

Newmar did the paint work and some fairly extensive additional roof work N/C even though it was well out of warranty. After I re-seal the rest of the penetrations, the roof should be good for a while, but I’ll make closer and more frequent inspections.

 

[Fish]

I think this is what you’d call a clue. I removed all of the old stuff and re-sealed it, so it should be fine, but it looks like all the rest of the penetrations aren’t far behind. We are scheduled for a heavy rain starting tomorrow night so it will get a good testing.
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I caulked my roof lasted year, and then again this year before I painted it. No way I was scraping off the mile of dicor or whatever they used back then.
I looked for cracks like in your pic and caulked them, and any lifting on the edges.

 

[Rich W.]

I caulked my roof lasted year, and then again this year before I painted it. No way I was scraping off the mile of dicor or whatever they used back then.
I looked for cracks like in your pic and caulked them, and any lifting on the edges.

I’m going to just fill any more cracks I find like the ones in the pic for now, then sometime next spring I’ll re-do the more serious ones. It took less than 30 minutes to completely remove all the factory goop on that vent so its not a terrible job.