Resealing a vent from the top vs R&R

[silverbullet555]

Our new to us camper needs to have the normal sealing maintenance done. Some of it is being done by a shop as they are removing a window and resealing it.

We had a heavy rainstorm last night and I found I had water come in from the emergency hatch which the shop will be taking care of on Thursday. I also found a few drips under another vent.

My question is, when do you seal only from the top using dicor self leveling vs removing a vent, replacing the butyl tape and topping off with dicor?

[JimK-NY]

HMS Beagle wrote:


And yet, I've seen multiple cases of failure within 2 years, on factory sealing jobs. It cracks at the edge of the flange were there is guaranteed to be movement. ....

This is a separate issue. Many RVs are really poorly built. The joints move and open up cracks that are often quite large. Dicor does a great job of sealing even with some movement because it remains flexible. Even so no sealant can withstand a poorly built unit with lots of movement.

My RV is 18 years old and I have owned it for 10 years. I needlessly replaced some of the original sealant when I bought the unit. The original sealant and that I added 10 years ago is still good. I do inspect every square inch at least once or twice a year. I have not added or replaced any sealant in several years.

[toedtoes]

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

And regular checks. Just because it should never leak, doesn't mean it can't happen.

Regardless of what you use or how you do the repair, the first rule in RV life is: check for leaks after the first rain of the season and after every big rainstorm.

Otherwise, that forever roof will spring a leak and you will arrive come spring to a soggy pile of nothing.

[HMS_Beagle]

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

And yet, I've seen multiple cases of failure within 2 years, on factory sealing jobs. It cracks at the edge of the flange were there is guaranteed to be movement. If it were really good for decades, there would not be dozens of threads on this forum about resealing your Dicor. Dicor is used only when price is the issue. Pouring it on top of a flange is at best a temporary benefit, and can be a longer term liability. This material is never used on yachts, where cost is less of an issue and sealing all important.

[JIMNLIN]

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

Many assume the sealant on top is Dicor.
I've done all the maintenance on my '97 32' 10" 5th wheel trailers roof since it was 3 months old. Having owned my own RV/mobilhome repair part time business specializing in exterior/structure (years ago) I do a twice a year roof check...once in the spring before hitting the road and late fall when put away for the winter where it sits for 5-6 months.
I've had to replace all roof jacks and fixtures on this unit due to the sun making them brittle and then crack or break.
I use the OEM method when reinstalling...butyle tape as the first line of defense then a self leveling sealant like Dicor over the scr heads and flange edge for the second line of defense against leaks. I never add a tape over any screw heads.

We saw many roofs where the owner had piled sealant over more sealant creating a dam for water to sit (lake effect). Very hard on sealants especially in the winter when it freezing and thawing.

Deciding when to just reseal or replace can't be made over the net or the phone. Each unit will be different than the next. Now if a roof jack or other roof fixture is broken/cracked then of course it will have to be removed and replaced.

[JimK-NY]

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

[covered_wagon]

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.

[HMS_Beagle]

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.

[toedtoes]

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.

[d3500ram]

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:

[silverbullet555]

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

[jimh406]

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.

[Kayteg1]

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.

[HMS_Beagle]

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.

[covered_wagon]

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.