Ceiling Vent Fan Leak Caused By Cracked Vinyl Base

[Steppy]

The 2004 2720SL TM I bought last December developed a leak around the ceiling vent fan. It was too cold to be working removing old caulk so I covered the TM with a tarp to prevent further leaking and resolved to check it out come warmer weather.

That day came today. My plan was to completely remove the unit and re-bed it for a long term fix. The hardest part of the job was removing the old caulk gooped on the screws. After pulling the unit I observed that the vinyl base was cracked clean through in 5 places radiating out from the screw holes. Almost all the other screw holes had cracks as well but not completely across like the other 5. See the attached picture. It's obvious that the factory had not pre-drilled the vinyl screw holes and the screws cracked the vinyl.

I bought some 3/4 inch vinyl stock 4 inches wide (the narrowest they had) at Lowes. I cut off 2 pieces 16 inches long as the original, and ripped them 1 1/4 inches wide.

I attached the vinyl to the roof using 3M Marine Adhesive Sealant. Then I mounted the unit to mark the hole locations for pre-drilling. I pre-drilled the holes then laid down RV trailer putty tape recommended to me by a local RV repair business. After installing the unit and replacing the screws, I did an extensive water test and observed no leaks

[Wavery]

Originally Posted by Steppy

The 2004 2720SL TM I bought last December developed a leak around the ceiling vent fan. It was too cold to be working removing old caulk so I covered the TM with a tarp to prevent further leaking and resolved to check it out come warmer weather.

That day came today. My plan was to completely remove the unit and re-bed it for a long term fix. The hardest part of the job was removing the old caulk gooped on the screws. After pulling the unit I observed that the vinyl base was cracked clean through in 5 places radiating out from the screw holes. Almost all the other screw holes had cracks as well but not completely across like the other 5. See the attached picture. It's obvious that the factory had not pre-drilled the vinyl screw holes and the screws cracked the vinyl.

I bought some 3/4 inch vinyl stock 4 inches wide (the narrowest they had) at Lowes. I cut off 2 pieces 16 inches long as the original, and ripped them 1 1/4 inches wide.

I attached the vinyl to the roof using 3M Marine Adhesive Sealant. Then I mounted the unit to mark the hole locations for pre-drilling. I pre-drilled the holes then laid down RV trailer putty tape recommended to me by a local RV repair business. After installing the unit and replacing the screws, I did an extensive water test and observed no leaks

It looks like someone got carried away torquing those screws. Sounds like you won't have to mess with that again for a long time.

Well to say timing is everything is an understatement. I was just logging into this forum to see what people have used to re-seal the very same vent. Our TM's been open for the past 2 weeks to stock it as an "earthquake ready" unit. Leaving in Southern Calif. and watching the current events has snapped us back to reality. While it’s been up we've had substantial rains in So Cal and I found that I've got quite a leak going on. I'm guessing that I should go the route that Steppy did and remove the entire unit and then re-seal, or can one get away with simply removing the old caulking and reseal from the top side? Also would everyone agree that the 3M Marine Adhesive Sealant is the right product to use?

Your advise will be welcome,
Bruce

[scrubjaysnest]

Originally Posted by b&pcamping

Well to say timing is everything is an understatement. I was just logging into this forum to see what people have used to re-seal the very same vent. Our TM's been open for the past 2 weeks to stock it as an "earthquake ready" unit. Leaving in Southern Calif. and watching the current events has snapped us back to reality. While it’s been up we've had substantial rains in So Cal and I found that I've got quite a leak going on. I'm guessing that I should go the route that Steppy did and remove the entire unit and then re-seal, or can one get away with simply removing the old caulking and reseal from the top side? Also would everyone agree that the 3M Marine Adhesive Sealant is the right product to use?

Your advise will be welcome,
Bruce

Our experience with other trailers and motorhomes is a complete removal, cleaning and reseal is the only option that works. We have never used the 3m marine sealent so have no experience there.

The 3M product is excellent, and well suited for the job. I would recommend it.

Try using a hair dryer to warm up the area that is caulked, it can make the removal a little easier.

[Steppy]

I used 3M 5200 Marine Adhesive Sealant. This stuff is used for permanent jobs and cannot be easily removed. I chose to use 3M 5200 harking back to my sailor days when I used it to bed down all deck and through hull fittings on my sailboat to fix leaks. After using it, I never had any leaks, even around through hull fittings under water.

I found that the factory sealed both the vinyl base and the vent unit to the vinyl base with some sort of clear rubberized sealer that wasn't applied very liberally. That coupled with cracking the vinyl base by not pre-drilling prior to screwing the unit down guaranteed there would be leaks.

Bruce, I'd strongly recommend pulling the entire unit to inspect the vinyl base for cracks. If yours is in as bad a shape as mine was, you'll want to replace the base as well and bed it down correctly and be done with it.

Ed

[Mrfixit]

Just had our first rain with the TM open ... yup- the vent fan leaks. I'll be removing it completely and rebedding as others have, but will be using 3M 4200. It has the same great sealant qualities as 5200, but if you ever need to remove the fan again, you'll be able to with 4200. The 5200 version is 99% permanent. A product called Anti-Bond will soften 3M's polyurethane sealant/adhesives somewhat if removal is needed.


Skip

Originally Posted by Mrfixit

Just had our first rain with the TM open ... yup- the vent fan leaks. I'll be removing it completely and rebedding as others have, but will be using 3M 4200. It has the same great sealant qualities as 5200, but if you ever need to remove the fan again, you'll be able to with 4200. The 5200 version is 99% permanent. A product called Anti-Bond will soften 3M's polyurethane sealant/adhesives somewhat if removal is needed.


Skip

Thanks Skip and Steppy for the low down on both 3M products. I like the idea of being able remove the fan in the future, so I'll look at the 4200 product. We've still got dark skys so it's going to be a while before I can get to this project. Is there anything else I need to look out for in removal of the vent?

[Steppy]

On my 2004 2720SL , the screws used to mount the fan vent have square holes n the screw heads rather than being philips or regular slot screws. After pulling the cracked vinyl base, I gently tapped down the metal pulled up by the screws going into the roof to allow the new vinyl base to sit flush to the roof. I also made sure the old screw holes in the roof were covered well with the 3M 5200.

After applying the sealant to the roof and placing the new base I made on it, I used 8 clamps to hold the base secure for a couple hours to make sure the base was set to the roof.