During heavy rain found water on table next to head of bed. Upon inspection it seems that the trim along cap seam was needing to be redone. I am in taking trim off cleaning. The sides where all smeared with silicone so using mineral sprits and scrapper to remove silicone. Then I am washing with soap & water to hopefully remove any silicone residue so that dicor will stick to fiberglass. Under the trim will use butyl tape and then seal edge with dicor.
Also I am putting dicor between the 2 panels as I put trim back on.
Ken
You might want to try isopropyl alcohol as a remover or one of the adhesive removers such as
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Silicone is nasty stuff, hard to remove, very hard to clean well enough to get anything to stick on top of it including more silicone.
I used 3M 4200 UV adhesive. It doesn't get as dirty looking as dicor in my experience.
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Be sure to put sealant in every hole before the screws go back in. Put some on the screw as well. Don't over tighten and strip the screw holes.
Roger
I assume that mineral spirits is enough after subbing to get all visible silicone off. Then 3m or dicor will stick? Have have some 4000.
Ken
It's a future job of mine as well. I've noticed that there were some leaks in the past in that same area. My plan is to do pretty much what you're doing except for I overdrill each hole about twice the size, fill with a thickened epoxy that I make with west systems and a thickener, and then have the screw go into that with a pilot hole. Butyl tape to seal it all up. I've got several tubes of dicor so I'll probably use that but I also have a clear sealant that works really well too.
My plan is actually to do all of them not just the back cap. Although if I go to Mexico next year and have the coach painted down there I may just get them to do it. My plan is also to have the roof painted and it would be a perfect time to do it all. I've thought about removing the ladder on the back as well and just filling in all the holes with the epoxy. Don't like really using it much. And I have a ladder that would get me to the top from anywhere on the coach. With all of the solar panels up top navigating it can get a little bit tricky. And I don't find that those RV ladders are all that stable anyway. Coach would look cleaner without it as well. But I do have a new ladder that the previous owner left with me so maybe I'll just put that one on. I did take off the useless luggage rack which was just a trip hazard and temporarily sealed the holes with sealant. Good luck in your project!
I pulled all of my seams and glued the caps on with structural glue while adding to rivets between the screws . Now the screws simply hold the trim on.