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Old 04-18-2016, 01:06 AM   #1
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Vent install- Eternatape over screw heads?

After way too many hours, finally got my new MaxiFan on and almost weatherproofed. Used 2 rows of butyl under the flange, and then non-levelling Dicor at the edge.

Would like to put a final layer of Eternatape on, but how do you deal with the protruding screws? Seems like the tape would wrinkle as you went over it, rather difficult to get a good seal in a wrinkle.

Anyhow, some pics.
Bothe the sides of the fan hole were literally unsupported. the fan base was just screwed into the fiberglass roof and the luan:





I made up some filler pieces, and epoxied them to the luan to provide something for the MaxiFan base screws to sink into: These pics were of the trial fit before being epoxied in place:





After I had predrilled my holes; looks like swiss cheese: the holes I drilled, the ones the previous fan were held on with, and the duplicate set that someone at AS screwed up on. I cleaned out the un-needed holes with a drill bit, and filled them with Dicor prior to applying the MaxiFan base with the butyl:



One more edge to caulk with the Dicor:


And the final result: you can see the edge of the previous caulk - over 2" wider on each side...


So. Back to the original query. Do most people just apply the Eternatape over the screws? There has to be a better way. I was almost tempted to get out my countersink bit and recess the screw holes for a flat top screw. But the MaxFan folks appear to have provided the bare minimum of support around each screw. The bottom of the flange is relieved to the max; there is prolly only 50% of the material left, with a small solid boss for each screw support. They may have saved at least a dime of plastic on each fan... maybe a dollar tops. Jeez.

Anybody solved this other than by slathering a tube of Dicor on each side building up a flat ramp for the Eternatape to stick to?
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Old 04-18-2016, 07:09 AM   #2
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Use of Eternabond tape at your peril! I have seen tape delaminations over the last 16 years that I have been in the RV industry that allow water protrusion on almost every installation that has it. The stuff does NOT PERFORM as advertised and is nearly impossible to remove cleanly if you want to replace it. The small dimples in your roof will also defeat the bonding abilities of the adhesive that the tape uses.

You are far better off using a quality polyurethane like SikaFlex and manually smoothing it over your coverage area, or using a quality self-leveling sealant like Alpha 1021. I also would NOT USE DICOR as it is very high in VOCs and will show cracking as it dries that are usually visible within 6-12 months of application.

Sika also makes a good self-leveling sealant called 715.
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Old 04-18-2016, 12:46 PM   #3
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Thanks for your response.
Interesting. Yours is the first post I have seen cautioning against it's use. It has been almost universally praised as the best solution, period.

The PO's had apparently used Dicor everywhere; sometime up to an inch thick...Maybe 70% of it has also started cracking; I knew that VOC's are nasty in the EPA world, but did not make the connection to eventually cracking in the long run.

My intent was to used the Eternatape as my 1st line of defense; with the Dicor sealing the base to roof edge seam, and the butyl under the Fan flashing.

Sounds like you are recommending to basically enlarge my sealant joint? Probably covering the screwheads totally, and then widening the sealant are on the deck?

Any pics of what you would consider a well-waterproofed fan base?
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Old 04-18-2016, 06:10 PM   #4
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I have used Etra.. For over seven years. Still perfect.
Pff
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Old 04-18-2016, 06:32 PM   #5
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Here are a couple of shots pertaining to this topic.

One is moisture that gets beneath the Eternabond tape. It was very pervasive and even rested the mounting screws of the fan. This was a change-out of a Fantastic Fan for a MaxxFan.

The next shot is of a skylight replacement on a large motorhome that the client cracked when he slipped on his roof. The original was sealed with Alpha 1021 and the photo shows the new skylight with the same sealant used. 5 tubes to be precise.

You will not find ANY major RV manufacturer that uses Eternabond tape. Many DO use Alpha 1021 self leveling sealant, as it is very low in VOC, cures to a thick, hard rubbery consistency and is extremely tenacious when bonding to many surfaces when properly prepped; metal, fiberglass, TPO, EPDM and vinyl. IT DOES NOT LEAK!!!!!

Many of you apply this stuff ONCE and think it's great. I remove tons of it when changing roof components like fans and skylights and more often than not find excessive moisture beneath it.

Just string MY experiences over the last 16 years as a full time RV tech.

It's your coach….use what you like!!
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Old 04-18-2016, 06:46 PM   #6
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That picture on the left looks like someone did a really poor job of prep'ing the surface before applying the Eternabond tape.
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Old 04-18-2016, 06:54 PM   #7
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My experience is similar Lewster's.
A PO had used Eternabond tape on my Safari around a Fantastic fan. It delaminated in spots and leaking like a sieve.
Never again will I use any kind of tape flashing that is exposed.
I used Dicor on the screws heads and around the perimeter, three years ago. It still looks good, no cracks.
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Old 04-18-2016, 07:32 PM   #8
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Quote:
Originally Posted by PaulnGina View Post
That picture on the left looks like someone did a really poor job of prep'ing the surface before applying the Eternabond tape.

That's the tape's adhesive residue remaining after scraping the tape off the roof.
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Old 04-18-2016, 08:44 PM   #9
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Quote:
Originally Posted by lewster View Post
That's the tape's adhesive residue remaining after scraping the tape off the roof.

I still say that on a properly prepared surface, a properly applied Eternabond tape will stick much better than that. Any way of telling if the tape was rolled when it was applied? The Eternabond on top of my Avion was applied per their guidelines, including the use of a roller. It isn't coming up unless I make it come up. ( and I expect it will be a bear to get up if it ever is removed.)
Shoot, even with lots of years in the business, I wouldn't be assured that it was done right unless I was watching it being done. (Which will never happen, just like I won't let anyone do an oil change on my vehicles. In my experience, the give-a-crap quotient of repair facilities is very low these days..... Not just in the RV world, either. There ARE exceptions, though,)


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Old 04-18-2016, 09:56 PM   #10
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Eternabond applied 6 years ago, stopped vent flange leaks and has not leaked, delaminated, curled, yet. Trailer sits outside, on Louisiana gulf coast in torrential wet, salt, humid, high UV, hot weather. Don't understand the tape issue unless maybe freezing damages it.
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Old 04-19-2016, 09:11 AM   #11
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Jeeze. So much conflicting info, and everybody appears to have valid info.

I like the tape, because the concept seems to work so well; and it looks ...finished. But Lew sure seems to have valid points, in spite of all the testimonials...

The goop certainly looks effective, but it looks like a last minute solution (How we gonna keep this from leaking Joe? Easy Fred, just put a bunch of sealant on top), and every occurrence I have seen where it was used, it has eventually cracked and looks like crap. Guess that is to be expected, as it is exposed to the sun and the elements every day.

Guess nobody has REALLY solved this? Something like goop on the inside, covered by a fiberglass or stainless trim piece that would cover the goop and not allow it to be deteriorated by the weather, and also make it look like it was a thought out design solution...

Hey, this ain't rocket science.
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Old 04-19-2016, 09:46 AM   #12
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This is the first I have ever heard negatives on Eternabond tape. I used it extensively on vintage Scotty rebuilds for seams and vent sealing with good experience.

BUT, I also prescribe to the theme "your experiences may vary."
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Old 04-19-2016, 11:59 PM   #13
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OK, the merits of Eternabond aside, there has to be a better way to do this. I spent some time in a boring meeting today and came up with this. A little crude, but the idea is sound; I think .



Screw detail:


A bona fide engineered solution - at least for a Maxx Fan base...

I'm going to stop by a friends shop who has a waterjet and a break and see what he thinks. Maybe 3/32" stainless, so no worries about metal distortion squeezing out the butyl as the screws are tightened. The screws are a bit pricey, but should last almost forever and NEVER leak. If they do, a new o-ring solves the problem.

Basically, a full sealed flashing on top of the current dicor/butyl seal. Sun proof, wind proof, rainproof (I hope)...

Comments welcome in case I missed something.... would not be the first time... The only problem I see so far is the corners. Hard to bend metal in a compound curve in a corner...
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Old 04-20-2016, 06:57 AM   #14
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Quote:
Originally Posted by pago cruiser View Post
OK, the merits of Eternabond aside, there has to be a better way to do this. I spent some time in a boring meeting today and came up with this. A little crude, but the idea is sound; I think .



Screw detail:


A bona fide engineered solution - at least for a Maxx Fan base...

I'm going to stop by a friends shop who has a waterjet and a break and see what he thinks. Maybe 3/32" stainless, so no worries about metal distortion squeezing out the butyl as the screws are tightened. The screws are a bit pricey, but should last almost forever and NEVER leak. If they do, a new o-ring solves the problem.

Basically, a full sealed flashing on top of the current dicor/butyl seal. Sun proof, wind proof, rainproof (I hope)...

Comments welcome in case I missed something.... would not be the first time... The only problem I see so far is the corners. Hard to bend metal in a compound curve in a corner...
Nice idea by WAY over-engineered and totally unnecessary, especially the second course of screw holes required to keep the flange to the roof. You do realize that the purpose of the butyl tape is to provide for a waterproof seal at the fan-base/roof junction? This material stays pliable thru it's life and maintains that seal if it was properly installed at onset. I have seen fan installations with no top layer of sealant over the screws that did not leak…..right from the factory!

In addition, it also seals the screw holes in the roof, making the entire fan base water-tight. The secondary coating of a self-leveling sealant is 'insurance' against any potential small gaps in the butyl tape seal.

This is why putty tape is no longer used, as for a couple of bucks additional per roll, you get a permanent, supple seal that IS removable if you need to change out or remove that base.

Even on the super high-end Newell and Prevost million $+ coaches, you won't ever find any roof seal other than butyl tape, stainless screws and a quality self-levelling sealant like Alpha 1021 (NOT Dicor).

That's all I have to say……………………I'm not trying to convince anyone of anything….simply giving you a 'professional's view with just a 'bit' more experience that the average RV owner and that of some of the major RV builders.

As was stated previously…………YMMV!

PS: If any of you are in need of a roll or 2 of Eternabond tape, I have some available still in the plastic wrapping. PM me……. Such a deal!!!!
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