A122S A-frame Lexan skylight installation

[RunningDog]

My first post here. We purchased a 2015 A122S in 2021. Eventually we found that all three skylights have the commonly reported cracks in the corners. Two of them leaked. White 4" Eternabond tape had been applied , but the cracked corners were still exposed.


I decided to replace them with Lexan (poly-carbonate) skylights, instead of the acrylic ones installed by Forest River. I'm looking for no more cracking corners, and high resistance to damage.


The trailer is prepped for the new skylights. I plan to top them with black 3" Eternabond tape. But what to use to bond the skylights to the fiberglass roof?


The manufacturer of the poly-carbonate skylights I purchased recommends silicon. I know silicon has detractors due in part to nothing ever sticking to the surfaces again. Butyl rubber has suggested as an alternative to silicon, and it is easily removed and reapplied if needed. And there are a variety of bonding agents such as SikaFlex 221, which is said to be permanent. The original epoxy used on my trailer is only available in bulk per one thread here.



I do not plan to use a lap sealer. Note that Dicor lap sealer is not compatible with poly-carbonate per the skylight manufacturer due to it containing naptha.



If you've installed poly-carbonate skylights on your A-frame, I'd love to hear what you used to bond it to the roof. The length of time needed for it to cure before applying the Eternabond tape will also be useful to me.


Thanks in advance.


Here's what it looked like when purchased, and with the skylights removed in preparation for the new ones:

[OYO]

Welcome. And thanks!

I have no input.

This is something I'd love to do, but ours are still keeping the water out. I just can't justify doing it for ascetic reasons.

Keep us posted.

[Fuji]

I have replaced the big one. Let me do some digging and find the adhesive that I used. It was recommended by the tech at FR.

[Fuji]

SikaFlex 221. Amazon sells it. It is not two part like the factory uses but they use this in a pinch. Use the black or white, doesn't matter. I wiped it down with alcohol first, let it dry then put a 1/4"- 3/8" bead of caulk on top of the old stuff. Set the new skylight on the bead of caulk and then weight down the edges with a 2x6 wooden frame. Throw a couple of concrete blocks on top of the frame for extra weight. 24 hours later, you can run the 4" EternaBond around the edges and roll down with a roller to make the bond permanent. If you need any more info, post back.

[OYO]

Originally Posted by OYO

Welcome. And thanks!

I have no input.

This is something I'd love to do, but ours are still keeping the water out. I just can't justify doing it for ascetic reasons.

Keep us posted.

I just realized spell check did me no favors: Aesthetic not ascetic.

Apologies.

[Czars]

I have leaky skylights also. Where can I get net LEXAN skylights??

[Fuji]

Eztopswordwide.com

[Larry-NC]

Lexan is a brand name; polycarbonate is the generic term.

The good news is that polycarbonate is a lot tougher than acrylic (Plexiglas is a brand name.). The bad news is that polycarbonate is a lot less resistant to UV (ultra-violet=sunshine) than acrylic. You will notice yellowing in a year or two, and it will be really yellow after five years.

[Fuji]

I think Larry is correct. If camper is stored outside, and not covered, you might want the acrylic ones. I have polished the two original small skylights with pretty good results. Not perfect, but you couldn't see through them at all before polishing.

[Czars]

Thanks for the info.

[Larry-NC]

Originally Posted by Fuji

I think Larry is correct. If camper is stored outside, and not covered, you might want the acrylic ones. I have polished the two original small skylights with pretty good results. Not perfect, but you couldn't see through them at all before polishing.

Unfortunately, the yellowing goes clear through, not just on the surface.

I replaced two flat (atop the slideouts) 1/16"polycarbonate panels with 1/8" panels. The original ones, 12 years old, had gotten yellow and brittle and one broke when hit by an errant pine branch. The new ones are thicker, but that just means they will filter even more light once they yellow. They are exposed all the time.

[Fuji]

This is the frame that I built to weight down the edges of the skylight once I applied the adhesive. Not shown is a couple of more boards laid on top with a couple of concrete blocks to further add weight. Be careful placing the blocks, you don't want to drop them on your new skylight! I think the best price for the skylight was $450 and was ordered straight from Camping World. Insane price for a piece of plastic, but I looked quite a bit and could find nothing less expensive.

[Fuji]

Forgot to add once I looked at the photo is I put waxed paper on the edges of the skylight before I added the wood frame. I was afraid that the adhesive might squeeze out and glue the wood frame to the skylight once the adhesive set up.

[mzak]

This is from forest river

[RunningDog]

Originally Posted by Fuji

SikaFlex 221. Amazon sells it. It is not two part like the factory uses but they use this in a pinch.

Thank you for the suggestion. I used SikaFlex 221 to bond my new vent/fan to the roof, followed by DiCor lap sealant then Eternabond tape. I've worried ever since that it will be too permanent, meaning the vent can never be replaced again because of the SikaFlex. For the skylights I was hoping for something that can be redone if needed. Like butyl rubber and Eternabond, which the skylight manufacturer says many of their A-frame customers use.


But permanent is OK. SikaFlex 221 vs silicone, any opinions?

[RunningDog]

Originally Posted by Fuji

I put waxed paper on the edges of the skylight before I added the wood frame.

Great idea, the waxed paper.

[RunningDog]

Originally Posted by Larry-NC

Unfortunately, the yellowing goes clear through, not just on the surface.

I replaced two flat (atop the slideouts) 1/16"polycarbonate panels with 1/8" panels.

Thanks for the information on yellowing. We are storing it mostly closed with a cover. What adhesive did you use for the flat polycarbonate panels you installed?

[RunningDog]

Originally Posted by mzak

This is from forest river

Thank you, this is interesting. I like the steel skylight weights, those must be what they use at the factory.


The Sika 3131 glue they mention is what they are using on the acrylic skylights. I think it is available in bulk quantities only.

[mzak]

Originally Posted by RunningDog

Thank you, this is interesting. I like the steel skylight weights, those must be what they use at the factory.


The Sika 3131 glue they mention is what they are using on the acrylic skylights. I think it is available in bulk quantities only.

It is available in 16.5 ounce cartridge but yes it is for acrylic.
https://weareissi.com/product/sikafast-3131/

[RunningDog]

Thanks again for all the suggestions. The new polycarbonate skylights have arrived and are ready to install.



I'm still not decided on what adhesive to use on the skylights. I have not had many specific suggestions from people that have done it with polycarbonate, and searches are turning up few specific examples.



The skylight manufacturer strongly prefers silicone. In another forum someone had success with Gorilla Glue construction adhesive with silicone around the edges. And no tape.



The skylight manufacturer let me know that many of their A-frame customers have successfully used butyl rubber followed by Eternabond tape. But I'm reluctant.



I have a confession to make. This is really Part 2 of this story, and it is the second set of new polycarbonate skylights that I am now installing. In Part 1, for the first set of new skylights I used butyl rubber, with Dicor self leveling lap sealer on the edges, followed by 3" Eternabond tape.


After a couple of weeks in the direct sun with the trailer open, the rear skylight slid down about 4", leaving a gooey trail of soft butyl rubber, lap sealer, and Eternabond tape adhesive. And an open gap at the top.


Why did this happen? Apparently the Dicor lap sealer contains naptha, which is not compatible with polycarbonate, per the skylight manufacturer. And, the Dicor lap sealer was not completely cured when I sealed it up with the tape. One or both of these might have contributed.


Luckily this mess was easy to remove. And the trailer is ready for the second set of windows. I just have to make up my mind on what adhesive to use.