Leak-Proof Roof Hatch and Fan Openings - Page 2 - Fiberglass RV

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Old 03-05-2014, 11:44 AM   #15
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Name: Russ
Trailer: Scamp 16' side dinette
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In theory the roofs of our trailers are molded with crown to allow water to run off without ponding. But in real life the roofs sag and allow the water to collect in the low spots. If the low spot is next to a roof hatch or vent the lapped joint is vulnerable to a tiny amount of hydrostatic pressure, and if the caulking is dried or un-adhered to the two surfaces the water will enter the interior. The added curb, if higher than the ponding water level could be an effective deterrent to leaking. It is true that dried caulking should be replaced when discovered. My Scamp is 10 yrs. old and so far has not shown any leaks. I have no idea what caulking material they used, but appears to be silicone. Silicone is next to impossible to remove adequately to allow any new material to adhere, so my reluctance to do maintenance. If and when it leaks I will tackle that.

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Old 03-05-2014, 01:23 PM   #16
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RV Putty tape goes on fine over where silicone caulk was removed with a razor blade. I also use a bit of acetone to remove any residue when recaulking.

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Old 03-20-2014, 10:24 AM   #17
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Name: Conrad
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I do a lot of fiberglass work, and this is a top rate professional job you did. Looking forward to seeing the final pictures.

For those considering this type of work, the hardest part seems to be cutting the hole. Once you get over the idea of cutting up a perfectly solid surface, you can accomplish anything!
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Old 03-21-2014, 07:29 PM   #18
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Yeppers, doubt there will be any "ponding" on the roof when peterh gets finished. Did you see all the mods he's done to lift the roof from the inside? Yeowser...
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Old 03-22-2014, 08:15 AM   #19
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Name: Larry H
Trailer: Trillium
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A slightly simpler solution?

My 2 cents worth-

Using ACE butyl Rubber caulk should work well.
It comes in several colors and stays somewhat
soft when it cures. Masking the edges is helpful
as the stuff sticks so well to anything that touches it.

Larry H
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Old 03-22-2014, 08:49 AM   #20
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Hmmm. I've used butyl tape, but that looks interesting. I have an entire trailer that needs all it's hookup ports and windows installed.

Just for clarification, I do think butyl tape does a great job and lasts a very long time, but trailers do occasionally leak, and depending on butyl tape creates a single-point of failure that can allow that to happen.

Installing a curb around any roof features creates a second engineering feature that would also need to be overcome. Perhaps this is silly, because I'm not creating a curb or gutter for our windows and other through-holes on the sides of our trailer, but with so many reports of people who have leaky fan vents, this seemed like a good idea.
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Old 03-22-2014, 09:32 AM   #21
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Name: Pam
Trailer: U-Haul 1985
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Very nice job, and excellent documentation. I think the curbing is brilliant, and when combined with proper maintenance, it will not leak. I would think that by building up the curb, the opening has been reinforced, so less flexing around the vent.
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Old 03-22-2014, 09:33 AM   #22
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Trailer: 1973 Hunter Compact II
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A properly done putty tape sealing job should last a minimum of 5-7 years with many lasting more than twice that long. Do we have any such history on this stuff in a tube?????

Most leaks are found on trailers that have not been maintained in even a reasonable manner. Joe buys a used trailer and, 2 years later finds a roof leak in what is now 15 year old putty, and declares that "Putty Tape is No Good" and piles on some other untried goop-in-a-tube that seals the leak, for a while.

When I removed the windows when I repainted my Hunter they had not leaked and the edges of the putty still showed evidence of the repaint color that was applied over 30 years ago.

My Rule #17: When I buy a used trailer I reseal everything on a horizontal surface and anything on the sides except the windows with putty tape. Windows I inspect carefully and remove and reseal with putty tape if there is any evidence of silicone type sealers gooped around the edges.

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