What is the preferred method of sealing new vent?

[Jeff_in_The_Dalles]

Last week I was working on removing the old lap sealant around the various vents and stuff on the roof, and reapplying dicor lap sealant.

While I had the sealant off, it occurred to me to be the perfect time to put a fantastic fan over the shower, in place of the noisy small fan...

I figured once I have the old one up and the electrical connections made, I'd run some dicor sealant around the opening, screw it down, and lap seal over the flange and screw holes...

The guy at the RV shop (who I trust) said they use butyl tape between the flange and the roof, then dicor lap sealant over the flange and screws. He said they get a good reliable seal, and if the vent has to be removed it is easier to do (avoiding damaging the EDPM).

The directions for the fan/vent say to use their gasket around the flange, followed by lap sealant over the seam and screw holes...

I was just curious, what's the preferred method of people here?

[TXiceman]

I replaced the vent on my old trailer with a new Fantastic Fan and I installed it with the supplied foam gasket and then covered the edges and screw holes with the Ertnabond tape. No leaks so far. This was recommented by my RV dealer.

Ken

[Ray,IN]

Jeff, both methods are acceptable. No lap sealant under the flange is correct.

[Jeff_in_The_Dalles]

Thanks guys.

It looked like the original equipment vent was installed with buytle tape between the flange and EDPM, with lap sealant over the edge and screws.

After looking at the supplied foam gasket, I went ahead and used it.

I don't know why so many RV's come with the small, loud, single speed fan. A nice quiet multi-speed one isn't all that much more, especially when you look at the price of the typical RV...

The only thing I've got left to do is to run back by the RV shop and see if I can trade the opaque dome for a translucent one.