Leaky Vents - Fiberglass RV

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Old 03-31-2003, 10:13 PM   #1
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Leaky Vents

(This note is from my husband, Mike.)

After having some leaking in the front ceiling vent on our way back
from CO with our newly acquired 1992 Scamp 5th wheel, I recaulked it over the weekend.

It is raining heavily this afternoon and when I went out to the
trailer, it turns out that it is leaking at both vents!

The caulking seemd to make no difference. I think my job was sound.

When I climbed up in the rain to look at the vents, I see some
hairline cracks around some of the rivets and the water seems to be
pooling on the ledge around the domed top of the cover.

The place where both vents are leaking is on the middle of the long
side toward the inside of the trailer.

There are two screws on each side that hold the metal bar in place
underneath the cover, but the water does not seem to be entering
where the screws are located.

Any suggestions on what to try now? Do I need to buy a new vent

Any help appreciated.


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Old 03-31-2003, 11:15 PM   #2
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Hi Mike
I had a few leaks in my Old Boler.I used silicon to make repairs.What I did was to remove all the old junk that was there and recaulked.Low and behold I still had a leak.What I found was that One of the hair line crackes was leaking.This took a long time to find.Did silicon repair and no more leak.Hope this helps,


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Old 04-01-2003, 07:29 AM   #3
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Water Travels

Hi, Mike

I have never seen a Scamp 5er up close and personal...only admired them from afar...so I can't be specific. We do have some others on here, so they will probably be able to help.

When I got my older Casita, I had a couple of very elusive leaks. Took me forever to find them, but find them I did and you will find them also...just take heart.

Remember...water travels. Since I have not seen yours, I can't say for sure, but my guess is that the source may be somewhere other than where you think. Mine was leaking around the vent pipe, hitting the top of the fiberglass shower and rolling down between the walls landing underneath where the city water inlet was. I drove myself nuts looking for plumbing leaks before I finally discovered the true source of the leak was on top. I even thought that it might be coming from one of the windows.

When you say vents, do you mean the vent pipes for the plumbing or do you mean the vents for air circulation?

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Old 04-01-2003, 07:44 AM   #4
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Mike ... did you remove the old caulk before recaulking (the preferred method) or just lay some new caulk over the old caulk (which sometimes fails to fix the leak, because of a broken or hardened caulk line)?

Also, what kind of caulk did you use? Go to a local RV or boating place and ask for help selecting a caulk. Try to get a caulk that is self-leveling and "hi flow." Self-leveling will give a nice looking caulk line. "Hi-flow" will allow the caulk to run and seek into many cracks ... however, you should only use "hi-flow" caulk on flat level surfaces. If you use "hi-flow" caulk on vertical (side of trailer), the caulk will just run off the trailer.

I assume that you caulked over the exposed screw and rivet heads? It's possible that whomever installed them, didn't "caulk the hole first." Failing to caulk a screw or rivet hole first almost guarantees a leak.

Now, if all else fails, and you are sure that there is not a hairline crack in the plastic vent cover, try getting some "Capt Tolley's Creeping Crack Cure." When all else fails, this stuff almost seems to magically find and fix an elusive leak.

PS ... since I assume the vents are standard RV vents (although most of them are square, so your "long side" throws me a little bit). If so, it wouldn't been too difficult for an RV place (or you) to replace both leaking vents with new ones.

Also, I will agree with Suz ... water you think is leaking from one place is often a leak "running" (even along the underside of a flat surface) from another place ... so broaden your search for possible leak sources.

PPS -- It's stuff like this that makes owning an RV a lot of fun, in my opinion! Have no fear, you'll find and fix the source ... and be able to fill us all in on how you did it!

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Old 04-01-2003, 01:38 PM   #5
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I agree with Suz, water travels all over the place in the layer between the outside roof and the inner ceiling.
Plus look over all the old calking see if something was calked that did not need calking. My trailer leaked very badly in the first couple of rain storms. I calked it with 7 or 8 tubes of silicon, leaks just got worse. Then I was working on the AC and realised I had added my calk to the old owners calk and it was sealing the AC cover to the roof and causing rain and condensate to collect inside rather than flow on under the edge of the cover and off the roof. The water had to build up to almost 2 inches deep before it would then flow over the inner lip, into the trailer through the AC hole . It fell to the floor out of the nearest light fixture.
Calk removed , leak stopped , owner embarrised, but dry.

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Old 04-01-2003, 07:56 PM   #6
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Leaky Vent

I agree with all that has been pointed out, especially trying to remove some or most of the old caulking. We had a leaky vent last summer as well that stained the ceiling somewhat on the inside. I was able to discover that the water was seeping through a hairline crack on the vent and then down a hole from a screw from the inside of the camper (kind of hard to describe!). Anyway I recaulked and everything is ok since. By the way, my gifted wife was able to mask the small stain area by sponge painting it. It gave a very close match to the rest of the ceiling , so much so that it is hardly noticeable! Don't despair Nancy , you'll solve it!

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Old 04-01-2003, 10:00 PM   #7
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vent seal

If it's a standard roof vent, new gaskets are available for em.

I wouldn't take a chance. :o

Remove the vent (both), have it done, whichever. Remove all the caulk....Get it fixed, replaced, resealed. Then sleep well on a stormy night. :)

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Old 04-01-2003, 10:59 PM   #8
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Leaky Vent Fixed...I hope

My wife Nancy posted my note about leaking vents here, and I appreciate all of your thoughtful and prompt replies.

I kept adding caulking to the places on the vent covers where we had hairline cracks and it finally worked!

I rained lots today and there were no leaks when I got home tonight.

Thanks everyone for your notes.

After spending time in communion with my trailer roof, I can see how putting caulking in the wrong place could create a little dam that might cause more problems. Thanks for the warning.

The information about different types of caulking was interesting. I had never heard of hi-flow caulk or the Creeping Crack Cure before.

I got the most expensive (GE type II) that I could find around here. I used that on a dry day over the weekend. Yes, I did remove the old caulking before I added new.

When we started having the leaks yesterday, Nancy found some caulk that works in the rain. The brand is Pro-Seal.

The Pro-Seal is a bit sticky to use. I ended up applying it on the general area with my caulking gun and then patting into place and shaping it with my finger after it had started forming a skin. I guess I finally reached the critical mass of caulk or pushed it into the right places after about 10 trips up and down the ladder. Phew!

I said that the leak was on the long side of the vent because the Scamp vents are rectangular.

The gaskets on the underside of the vent top look nice and pliable, so I think they are okay.

Thanks everyone, I will keep your helpful comments on file.

Mike Gillespie

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Old 04-12-2003, 09:05 AM   #9
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leaky vents

Check to see if the vent frame is plastic. If it is, you will almost never be able to stop it from leaking. The reason being that the plastic frame keeps cracking. I had the experience of installing a plastic frame vent once and it leaked within one year. After caulking and caulking and caulking I finally realized that the frame was cracking all over the place. Finally replaced the vent with a metal (aluminum) framed vent and installed with 3M 5200. No more leaks.
Good luck,
Rick D.

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Old 04-12-2003, 12:13 PM   #10
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leaky vents


I replaced my 2 year old metal framed vent with a fantastic fan which has a plastic frame. No problem here (yet).

And found that the original silicon caulk that the factory used did not adhere to the galvanized metal frame but stuck well to the fiberglass. Must be some difference between the galvanized steel and aluminum.

Aren't all fantastic fan frames made of plastic?


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