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Old 04-29-2019, 08:33 PM   #1
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EternaBond vs Dicor Lap Sealant Repair on Rubber Roof

Was upon the roof cleaning skylights, vents and AC cover etc (lots of black spots, mold I assume), and the Dicor lap sealant (or whatever they used) is pretty bad, even though I have no apparent inside leaks, and have had tons of rain this season.

Not sure exactly what the roof material is, but when I removed the inner shower skylight I can see it's a rubberized material with a velour-type backing.

Been reading various threads, folks saying remove all the caulk, then redo with Dicor, others saying use the EternaBond tape over the old sealant after cleaning it up is just as good, but may make it more difficult to replace vents etc later on. Also have seen videos of the tape installation, and like the way it looks, and folks have said it's lasted many years.

I've already ordered a roll of 4" tape and whether I use it or not, will keep in the the MH for emergency repairs. Just thought I'd toss it out there to see if anyone had any more pros or cons either way.

Entire roof needs a good cleaning, open for suggestions on that as well, though the spots seem to come off even with Windex.

Shots below are of the shower skylight, which has the worst sealant cracking, yet no evidence of leaking yet when the inner skylight was removed. In the close shot you can see the fuzzy underside of the rubber roof material (2010 Tioga 28Y).
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Old 04-29-2019, 09:51 PM   #2
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I'm NOT a fan of applying eternabond over Dicor and wonder why people even think about doing it. Why would you take a lumpy, leaky, uneven sealant and then try to put flat tape over it, even though it is moldable. To me......you either remove the old sealant and reseal with new Dicor, or remove the old sealant, create a flat clean surface and install eternabond.

I think for vents, skylights and other uneven surfaces, the self leveling Dicor is the best choice. The eternabond is good for flat joints like roof seams.
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Old 04-29-2019, 10:55 PM   #3
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Don - On our Bounder, I did a variant! I removed old sealant, cleaned well with Acetone, applied new self leveling Dicor, and the topped with Eternabond.

An old timer tech at Holland Motor Homes in San Diego (Now San Marcos.), suggested that was as good away as any to approach what he called a 'One time maintenance repair!'.

He said for sure, to get the old caulk off, and closely inspect from every angle I could, to ensure no water damage had already started. (And if so, address that damage!). His view was that the self leveling Dicor, added a secondary line of defense, in case the Eternabond was ever compromised.

He also told me to other tips, that I've seen repeated over the years on various threads, on how to apply Eternabond.

1) As mentioned, clean well with Acetone
2) Once Ertnabond is down, go over it with a small 4" wallpaper like roller, and be sure it's got a solid connection the roof, and other areas (Like say the Skylight.).
3) If any wrinkles and or air pockets, cut the tap with an razor blade, and roll over it again with the wallpaper roller, until all air is gone.
4) Especially on leading edges of Etnernabond towards the front of the coach. Apply a bead of Dicor sealant. (It helps gains 50-70MPH's driving, in a rain storm.) He said if you have an area like a skylight, where perhaps a part of the Eternabond tape is sloping upwards (Like on a dome.), to go ahead and caulk that area too...

I did all of his recommendations on our 98 Bounder T28 roof. I did the front and rear cap seams, around the skylight, and also along all of the areas the roof tucked into the sidewall going down over the curved roof. (Sometimes Fleetwood, and others, EPDM roofs would pull loose from the seam to the top rail where the sidewall was. So I ran two 4" wide strips of Eternabond, all along the sides where the roof tucked in.)

The gent I sold the coach to in 2010, does a yearly deep washing of the roof with Dawn, and said that the tape was holding up well. Around 2016, he told me he'd scraped loose as much of the caulking from around the edges of the Eternabond as he could. Cleaned with Acetone, and then applied fresh beads of Dicor Self Leveling caulking to the leading edges, and on the seams where slopes ran down, like the skylight.

I think the key to roof maintenance and a dry coach, is good maintenance. With, or without, Eternabond tape. Yearly close inspection is important, and fresh caulking where needed is too...

To be clear, I do agree with Don that putting Eternabond over old cracking caulking, is not a good practice...

Best to all, have fun, be safe,
Smitty
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Old 04-30-2019, 05:29 AM   #4
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Mine look like that used heat gun to remove old caulking then applied tape then self leveling caulking
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Old 04-30-2019, 07:49 AM   #5
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Quote:
Originally Posted by Dutch Star Don View Post
I'm NOT a fan of applying eternabond over Dicor and wonder why people even think about doing it. Why would you take a lumpy, leaky, uneven sealant and then try to put flat tape over it, even though it is moldable. To me......you either remove the old sealant and reseal with new Dicor, or remove the old sealant, create a flat clean surface and install eternabond.

I think for vents, skylights and other uneven surfaces, the self leveling Dicor is the best choice. The eternabond is good for flat joints like roof seams.
Thanks for the response. I'm assuming that glop they slopped on there is not self-leveling Dicor? I guess there's two versions, one for vertical surfaces, and thinner self-leveling for horizontal, but they used the vertical version on this.

The only reasons I'd consider putting the tape over it is that no one sees it but the birds, it IS still sealing, so I would be adding to the seal, and there's less chance of damaging the rubber roof material if I don't scrap it off.

Other than that, I agree it should be removed and done right BUT I also don't want to do harm in the process. That rubber material isn't very thick, and it's just Styrofoam underneath. If it were a fiberglass roof, I'd remove the old stuff for sure.

From videos I've seen they cut 4 pieces for the vents (overlapping the ends) and it is very moldable. Actually doesn't look bad afterward IMO, and again... it's a roof, not the front end of the vehicle. Looks are less important to me than function.

BTW, not arguing with you, just thinking it through.
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Old 04-30-2019, 10:00 AM   #6
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Reading around, I see the sealant Fleetwood slopped around this shower skylight was probably Surebond, not Dicor. Have the tape coming today, I think I'll get up there and see how stuck it is, maybe go ahead and try to pry it off. If it's stuck really well, I may just clean it and the roof area around it with alcohol, and tape over it. Just don't want to compromise the bond between the rubber material and surface below it by using acetone or aggressive prying.

Have read about first putting a strip across the back, extending out from the skylight a few inches, then down the sides, overlapping the tape in the back, then across the front, overlapping the side strips is a good idea. Then maybe some self-leveling Dicor to smooth the edges and protect from wind lifting the tape.
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Old 04-30-2019, 12:30 PM   #7
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Quote:
Reading around, I see the sealant Fleetwood slopped around this shower skylight was probably Surebond, not Dicor.

Maybe more recently, but back when it was the Fleetwood Corporation (not Rev Group), they used Alpha Systems self-leveling lap sealant on horizontal surfaces. No practical difference between that and Dicor.
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Old 04-30-2019, 12:38 PM   #8
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I'm with Dutch Star Don - caulk (whether self-leveling or cling) is easiest & best around uneven surfaces, corners or curves. Tape (Eternabond of Dicor's equivalent) is better suited to smooth, flat surfaces. I'm a fan of Eternabond, but it's not the answer to every situation.
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Old 04-30-2019, 02:04 PM   #9
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Thank you all for the comments and suggestions.Yes Gary I saw that Fleetwood also used Alpha, which this may well be. I just scraped most of it off and underneath it's still very pliable and seems well-sealed as-is. Thinking of scraping a bit more to level then tape it off, or maybe get a tube of Alpha or Dicor?

Of course another question is: I probably should replace that 9 year old skylight, but there's no cracks, and I can see they've used some kind of black adhesive underneath. May be a real bear to remove. Hmmm...
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Old 04-30-2019, 02:15 PM   #10
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EternaBond vs Dicor Lap Sealant Repair on Rubber Roof

Most likely butyl tape under the flange . After seeing what happens over time when Eternabond is placed over failing caulk I would never do it on my coach. I would clean and use Dicor to get a fully sealed surface. Then if you want a layer of eternabond it is then a third layer of protection.
Your “sealing” edges are pretty small around the skylight all it takes is a very small opening and now water is free to move around in all the cracks of your failing caulk. I have seen this in multiple locations on my coach where a PO placed Eternabond over failing caulk.


Here is a good example of what happens. Water was present under the tape and was free to move around and also cause rusting on fasteners and further deterioration of the caulk. Eternabond bond was also slowly failing and not attached in many areas.
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This is the same area after cleaned and sealed with fresh Dicor Self Leveling.
Has not fully leveled out as this was shortly after application.
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Old 04-30-2019, 02:22 PM   #11
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I recently removed and resealed my shower skylight. I went with Butyl tape as the sealing gasket and then dicor at the seam and the screw heads. Happy with the results
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Old 04-30-2019, 02:32 PM   #12
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A good place for using eternabond over dicor or any other sealant would be at the end caps. Sealant needs to be able to stretch. Where it bonds to the substrate, the distance between bonding points is the amount of room it has to stretch. In the building industry, we always allow 4 times the estimated movement to determine how wide the sealant joints need to be between bond points, so 1/4" movement = a 1" wide joint. The end caps experience more movement than any other sealed joint on the roof. There is not enough distance between bonding surfaces for much movement, only the thickness of the end cap. This will cause the sealant to begin tearing from the bottom up as it tries to stretch but can't. Those are in my opinion always the first joints to fail. Putting eternabond over the sealant will create a lot of room for the eternabond to stretch because it will not bond well to the dicor or other sealants. I used a preformed, precured silicone sealant strip on a previous rv set in silicone sealant, a very high quality silicone, not bathtub caulk and it lasted for eight years and was still in great shape when I traded the coach.
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Old 04-30-2019, 02:44 PM   #13
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Quote:
Originally Posted by Spk64 View Post
Most likely butyl tape under the flange . After seeing what happens over time when Eternabond is placed over failing caulk I would never do it on my coach. I would clean and use Dicor to get a fully sealed surface. Then if you want a layer of eternabond it is then a third layer of protection.
Your “sealing” edges are pretty small around the skylight all it takes is a very small opening and now water is free to move around in all the cracks of your failing caulk. I have seen this in multiple locations on my coach where a PO placed Eternabond over failing caulk.


Here is a good example of what happens. Water was present under the tape and was free to move around and also cause rusting on fasteners and further deterioration of the caulk. Eternabond bond was also slowly failing and not attached in many areas.
Attachment 244218

This is the same area after cleaned and sealed with fresh Dicor Self Leveling.
Has not fully leveled out as this was shortly after application.
Attachment 244219

Yep, I'm coming to the realization that the EB tape is not a good solution for the skylight. Need some Butyl tape or caulk underneath if I replace it, then Dicor the top like it was, along the edges and over the screws heads.


Just watched a video of a tech removing an old skylight that the owner had put EB tape over the old failing caulk. It didn't seal and left a wet mess.
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Old 04-30-2019, 05:53 PM   #14
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There is no good reason to not remove failing caulk of any kind.
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