Installing a Fantastic vent with proper sealant

Nice work Jon. I was going to replace my crappy fan in the bathroom with a Fantastic one. So I am saving this tread for when I do.

Thanks.

I did not use the foam gasket. I would not use any gasket in this application and the one provided is polyethylene foam which it seems to me is particularly unsuitable. If the roof was crowned enough to require something other than sealant it should be filled with something solid and shaped to the crown, then wet sealed without a gasket.

Gaskets generally work if the flange and the surface are stiff enough to retain some clamping pressure between the fasteners over the long term. The flange is certainly not stiff enough, and the roof is suspect!

Great job and pictures. I had bad experience with the foam pieces after a few years. Removing the sealer etc I too sealed under mine without the gasket. Never had an issue after that. Great idea for the tape. Didn't think of that one.

Looks great. I use painters tape for all my roof work, too. Did you still use the foam gasket that came with the fan?

that is a very neat and clean looking job

When it is a clean as I can get it, I immediately peel the tape. This sealant can be messy and you want to have plenty of rags or paper towels and solvent available. The tape will have sealant on it and anything it touches will too! This is what the joint looks like after the tape is peeled. Resist the temptation to further tool or smooth the joint! You will only make things worse at this point. Note that I do not have the "finger fillet" so common to these kinds of joints. This thin tail of sealant does no good for anything in my opinion, and is most often the first point of failure as it peels up. The sealant that is doing the work is between the flange and the roof:



The completed install. I would guarantee no leaks on this without any maintenance for 10 years, and would be very surprised if it leaked in 20 years:



In contrast the factory installed Fantastic vent just aft of this one already after 4 years has nearly total failure of the secondary sealant smeared on top, the black cracks are due to dirty and water collecting in the failed sealant. It doesn't leak yet but will be a mess to clean up and do right:

Next I applied a double bead of sealant to the roof. I want it to squeeze out of the joint, but due to the roof thickness and vent spigot, there is no opportunity to clean up on the inside, so I put a smaller bead towards the inside:



The vent is carefully dropped into place. I but a small dab of sealant in each screw hole, This will wet the screw threads and seal under the head:



I installed the screws, making them up just barely snug. I do not want to squeeze all the sealant out, a thicker joint allows for more movement without failure. There is a little bit squeezing out from under the screw heads too. Fantastic provides steel flat head screws, but I substituted SS oval head screws instead. A flat head will sink into the countersink on the flange, leaving a small pool for water to collect in a very vulnerable spot. The oval heads fill the countersink and shed water. Every little detail counts! I then raked the sealant off tight to the flange with a sharp cornered tool:



This is how it looks with the excess sealant removed. I want to remove all the sealant I can without undercutting the joint. I also wiped a bit around the screw heads, mostly this is the "obsessive attention to detail" of which I have been accused: