Resealing a vent from the top vs R&R

I would never remove a vent unless the roof is getting replaced.

I clean real well around each vent and then I blue tape a nice straight line square configuration around each of the vents. After taping I then use self leveling Dicor and work with a throw away brush working it back and forth well into the surface. This helps keeps it from building up so high and works it into the surface to help assure good adhesion. After working the Dicor to a relatively thinner area nearer the masking tape I slowly pull each piece of tape off, carful not to mess up having a nice clean line.

Should be good to go. I have been doing this to each of my vents twice since I bought new 18 years ago.

That depends on whether you want to do it once, right, and have it sealed for 10 - 15 years or do it every year. Dicor poured on top of the flange is never done on a boat, with good reason - boats sink when filled with water, campers just slowly rot.

Per my experience - butyl tape is the only thing that seals permanently, or let's say 20 years.
All caulking on the top is a band-aid who require annual rechecking and even then some caulk would look good to the eye, when in fact it did not stick on 1 side and was channeling water inside.
Also I found Henry's roof sealer (about $50/gal) the only thing that sticks to everything and last if you want to recoat whole roof.
The roof sealer alone is not good joint sealer as it shrinks when dries.

I think Dicor sticks better to a clean surface which could include other Dicor. I’ve scraped away Dicor to get to clean Dicor. I also wouldn’t remove a vent either unless it’s broken, and I had to.

I’ve used Henry’s on a house, but I wouldn’t use it on an RV. Not saying it could work, but it’s really messy compared to Dicor or Eternabond.

Looks like we are 50/50 on removing and redoing vs resealing from the top.

If it were me, I would remove, inspect and reseal. If you have a leak on a camper in which you do not know the history then it may also be that you do not know what is going under the roof components.

If you had a leak at one time (even if it is sealed now with whatever method) you still may have a ticking time bomb. What I mean is that depending on how much moisture got in, there could be potential for damage.

I bought a 2 year old camper in brand new condition in 2010 and I religiously maintained as best I could. Yet still there was an instance where water unbeknownst to me got in somehow. I discovered it some 6 years later coming in the adjacent vent when doing maintenance around the shower bubble; I ended up replacing and sealing both using eterna-bond where I had to cut back some of the roof membrane, butyl tape and dicor:

Before:



After:

If you get a sudden leak while out camping - recaulk so you can enjoy the rest of the trip, then come home and remove and repair. If you get a leak while home, remove and repair.

If you do remove and reseal, use a proper sealant like 3M or Sikaflex polyurethane. The one I particularly like is 3M 4000UV. What you use will depend on the roof material. No matter what you pour on top of the flange, it will fail, and fairly quickly too. Eternabond will work for awhile because it is thick enough and flexible enough to bridge the moving joint.

In 18 years I mask and coat them like a painted rubber membrane around them and Over the flange, screws and onto the roof for 3-4 inches. Looks nice when masking is pulled leaving a nice clean line. Never have leaked. When you spread it out like that you get a chance to see any spots in the future that wore thru or have become compromised from the elements. See post above as just placing a bead around is hard to tell where the problem may be. When you spread with a brush you are working it into any voids crevasses and going back and forth assures good adhesion.

Assuming proper surface prep, dicor lasts for decades. It should never crack, peal or develop any leaks. Again, it requires proper surface prep.