Fan sealant

[KaLvan]

How often should we reapply DiCor self leveling sealant around our roof fan? We put the fan in 2 years ago and sealed it at that time. All still appears to be fine (no water leakage). Should we apply more for prevention? Any advice appreciated.

 

[bullfrog !]

Every RV manufacture I know says to check or replace yearly cause they don’t want to honor warranties. It will “dry up” shrink and eventually leak if not scraped off and replaced. I started using automotive windshield sealants on my builds and thicker metal framing after owning a Barth Class A motorhome with heavy aluminum framing. DiCor self leveling is the industry standard but does require frequent inspection and replacement as once you get a leak any wood that gets wet will most likely mold and need to be replaced.

 

[maki2]

The butyl rubber mounting tape is what is doing the primary sealing job. That is considered to be a lifetime product. It will harden on the exposed to air surface but remains soft where not exposed to the air. The Dicor is an additional topper that is mostly protecting the screws used to install the fan. When I install items such as a fan or other items where screws penetrate into the interior structure I put butyl rubber tape around the screw threads from top to bottom. That keeps rain water from running along the helical threads using them as a pathway into the interior of wood framing. Excess butyl tape will squeeze out under the screw head as the fastener is tightened creating an even better seal under the screw head instead of just a Dicor coating over it. A simple belt and suspenders approach to prevent those pinpoint leaks from screws but the butyl rubber tape while helping prevent screws from backing out from vibrations does not make them difficult to remove as it stays pliable along the screw threads as it is not exposed to UV. .

Understanding how things are installed and mounted and what the properties of the various sealants are and what they do and which ones work best for a task leads to greater piece of mind as well as the ability to DIY fix things if a leak should develop or an accessory such as a fan needs replacing.

 

[jasper]

The eleven year old fantastic fan on my camper recently developed a very small leak. The original clear sealant seemed well bonded. Finally, after a lot of testing, a small, almost invisible crack showed up in the flat white plastic between the upturned lip underneath the top cover and the sealed outer perimeter edge.

The original sealant was clear and definitely non-leveling. It looked like a sealer I've used called Lexcel, in a toothpaste type tube or caulk gun tube. That caused water to build up, moat-like, and drip through that barely perceptible crack. I already had the tools ready and really dreaded removing the sealant. The Lexcel cured the leak.

It's a tough call deciding to fix it if it ain't broke.

 

[maki2]

For some plastics the watery thin clear scale model makers Testors brand, that kind that comes in a small bottle with a brush cap, will literally melt then dry and weld the edges if a hairline crack back together. I keep a little bottle of that in my repair kit. It saved me a hundred dollars when my portable toilet developed a few cracks. I also used it to plastic weld seal a couple of cracks in a polycarbonate over the cab front window on an older Sunrader motorhome. That saved the owner hundreds of dollars versus replacing it. It does not work on every plastic type such as the soft plastics, think milk bottles, but it works great on many of the hard plastics. Being a very small bottle it does not take up much room in a roadside repair kit. Hobby Lobby stores have it in the model cars hobby area. I doubt it can be shipped via the USPS even though it is a very small bottle.