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Removing factory rooftop fan, put dime size hole in membrane - dumb

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  • Removing factory rooftop fan, put dime size hole in membrane - dumb

    I have a number of issues today with our 2022 2500RL and I am having a hard time finding information -

    1 - taking out factory toy fan on roof to replace with Maxair. Pulled a dime size piece out of the membrane about an inch away from the fan mounting. I see all over if you rip the membrane it has to be replaced. I have the recommended Alpha lap sealant I will be using when I get the old stuff cleaned up. And I saw some YouTubers not using lap sealant at all and using Eternabond instead.

    I don't think I will go that way, but after the lap sealant is cured I am thinking of putting Eternabond over the leading edge since the little tear is in the toward the front of the trailer. After taking off that factory lap sealant I don't a hurricane will ever lift it.

    2 - I looked at the Maxair install instructions, and they said all the calk has to be removed for 2 inches all around. I am getting it pretty well down to the membrane, but doesn't lap sealant stick to previous lap sealant if it is clean and prepped properly? Is there a solvent that I can use?

    3 - the factory used some black stuff directly under their toy fan that to me is not as easy to remove as the gray stuff that I will use for the new fan. It is really hard to scrape off. Maybe heat for the remaining lap sealant the the black stuff? I'll be using the gray calking tape. Is there a solvent I can use?

    I had my best luck using an oscillating saw, low speed and a metal blade that I ground the saw part off and beveled. Loosened and pried with plastic scrapers.

    Thanks in advance - John
    Attached Files
    New 2500RL, F250 Super Duty Platinum Diesel

  • #2
    I would use a piece of eternabond for the hole then use self leveling sealant over that.

    Brian
    Brian & Michelle
    2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
    630 ah battery, Victron Multiplus 2, 800 watts solar, 100/50 SCC
    2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K

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    • #3
      low heat (hair dryer or heat gun on low) helps to remove old sealant. Then add in copious amounts of patience and persistence. "Rolling" the sealant with your fingers can work, too, but hurts after awhile(!). Be extra diligent to limit further damage to the roof.
      Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

      2017 Ford F-350 DRW, '19 315RLTSPlus

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      • #4
        After having used the self leveling sealers and eternabond. Either will work. HOWEVER MY OPINION IS: eternabond first, self leveler second if you plan to use both. The Eternabond over the leveler will not seal correctly.

        I did use eternabond on an H i had to cut in the membrane on our 1st trailer to fix the hole the tree limb put when it speared the slide.
        Joseph
        Tow
        Vehicle: 2018 GMC K2500 Denali Diesel
        Coach: 303RLS Delivered March 5, 2021
        South of Houston Texas

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        • #5
          Brian, Joseph and Howson - thanks for your input. Sounds like maybe Eternabond for edge to front where little hole is and self leveling over that and the rest. I will use heat to try and deal with the remaining calk and black goo. Appreciate y'all. Up on the roof today and maybe get this done.

          So glad I don't have to replace the membrane. Just kidding.

          I saw a YouTuber doing the same as me, also on a GD trailer, that suggested all the builders have a universal mounting so any fan could be swapped. Makes too much sense maybe?

          John
          New 2500RL, F250 Super Duty Platinum Diesel

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          • #6
            RV Tailors Personally I would run the eternabond all the way around. Cut the corners square and do not overlap the stuff.

            Idea is to keep the mounting flange of the fan on as close of a "flat" playing field as possible. The eternabond if on bottom before the fan is put on will leave a crack on the trailing edge of the tape under the flange where it changes elevation.
            Joseph
            Tow
            Vehicle: 2018 GMC K2500 Denali Diesel
            Coach: 303RLS Delivered March 5, 2021
            South of Houston Texas

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            • #7
              Yes Joseph, so far the plan is to put the butyl tape on the flange, screw the fan down, Eternabond over the flange on all 4 sides not overlapping. And self leveling on all inside and outside seams and edges.


              Did I get it right?
              New 2500RL, F250 Super Duty Platinum Diesel

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              • #8
                One more thing. Is the black butyl tape better than the gray? The black was on the old fan installed at the factory and it is incredibly hard to remove the residue and it makes a mess if I track it around.
                New 2500RL, F250 Super Duty Platinum Diesel

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                • #9
                  RV TailorsI have white, grey, and black Butyl tape. It's all the same stuff different color.

                  As for eternabond, that works. It sounded as if you were going to put the eternabond down first only on the front edge, then put the fan, then tube sealer. That's why I stated to not overlap and to do all sides. The Eteranbond on top of the fan flange is not really required, unless the hole is visible.

                  Plus like it's name states "ETERN"abond it's almost eternal. So if you ever have to remove the fan, it's not going to be pretty.
                  Joseph
                  Tow
                  Vehicle: 2018 GMC K2500 Denali Diesel
                  Coach: 303RLS Delivered March 5, 2021
                  South of Houston Texas

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                  • #10
                    Ok, scraped, picked, heated today. It is 90 deg here in cent Tex so heat didn't make much difference. I may spend some time tomorrow but I think I got as much as I can off without messing up any more membrane.

                    I will order the black butyl tape since that was on there by the factory. Might bond better. The Maxfan flange is wider so I will put two strips all around. I dropped the new fan in the hole for the night. I didn't check if the wider flange covered the hole. If the wider flange covers the hole I just go with self leveling with a little square of Eterna over the hole. I not covered by flange will go Eterna all around with self leveling.

                    Will check if the flange covers the hole tomorrow. I dropped the new fan in the opening but didn't notice if it covered the hole.

                    Have to order new butyl and Eterna as mine is to old to trust.

                    Thanks for your help and is much appreciated.
                    New 2500RL, F250 Super Duty Platinum Diesel

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                    • #11
                      If Eternabond tape is not to be overlapped, how does it meet up with 90-degree junctions? It doesn't 'SEAM' adequate to butt the edges of the tape to each other.
                      Last edited by aPair'OMacs; 09-22-2022, 01:11 PM.
                      Shane & Annette
                      Dillon & Ali, Min Golden Doodles
                      New to camping, learning the ropes
                      2021 GD Imagine 17MKE XLS
                      2017 Toyota Taco, SR5, V6

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                      • #12
                        Even if it's close but does not completely cover, the self leveling compound will seal the hole. As for the age of the eternabond. If it sticks, it's still good. I think mine is about 6 years old and would not think twice about using it tomorrow on the roof.
                        Joseph
                        Tow
                        Vehicle: 2018 GMC K2500 Denali Diesel
                        Coach: 303RLS Delivered March 5, 2021
                        South of Houston Texas

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                        • #13
                          From when I replaced my skylights. Eternabond first, butyl tape under the flange of the skylight then self-leveling covering it all. Hasn't leaked once.
                          Attached Files
                          Bill & Cindy
                          2021 Transcend Xplor 221RB
                          2021 Nissan Titan Pro4X
                          Central Texas

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                          • #14
                            Ok y'all - here is my plan (so far) from all the super appreciated help:

                            1 - Eterna, start at back flange, then do each side, then the front flange where the dime-sized hole in the membrane is about an inch in front of the front flange. Reason - cover that darn hole I made in the membrane and have the Eterna overlap in the proper direction, front to back.

                            2 - butyl (in the refrig now) on the flanges double wide on the sides, squish it out, trim it off that which was squished out. Reason - that's what we are supposed to do.

                            3 - screw the Maxifan down (hinge to the front). Reason - couple of YouTubes where the guy had to rotate 90 Degrees after putting it in wrong.

                            4 - garnish it after trimming aforementioned garnish. (don't screw measurements up) Reason - same as 2 and 3

                            5 - return to refrig for a Shiner. Reason - same as 2 3 and 4.

                            Did I miss anything or any comments or suggestions?

                            Thanks for your input - John
                            New 2500RL, F250 Super Duty Platinum Diesel

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                            • #15
                              Why is the butyl in the refrigerator? I would put it int he sun to let it warm up as hard butyl will not squish and seal. From personal experience the butyl may need to be trimmed a couple of times if it's squishing out the sides.

                              I don't think you need double wide Butyl on the flange. Do plan on putting it where the screws go through, but I think it's a secondary seal (oh crud type of thing) in case the self leveling compound develops issues, plus it seals the flange so the leveling compound does not run under if the decking is not 100% to the flange.

                              That's funny that people put the hinge any direction but forward. I always explain things about wind forces by saying "stick your hand out the window while doing 60 and lift the front edge". Even side mounting it will rip that cover off, plus you cannot put the vent cover on there https://www.amazon.com/Maxxair-503-1...s%2C119&sr=8-4
                              Joseph
                              Tow
                              Vehicle: 2018 GMC K2500 Denali Diesel
                              Coach: 303RLS Delivered March 5, 2021
                              South of Houston Texas

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