Newbie - Roof sealing questions

[twgiambra]

Hello, we purchased our first RV (2024 Imagine 25DBE) this past December. We just returned from a trip down I-95 (NC to Florida) and I inspected the roof. I see a few spots where the sealant seems to be slightly pulling away from the vents. I did search on Roof maintenance and see posts, but not seeing my specific questions answered.
My questions:

1. Is this normal for a new trailer (4 months since manufacture)? Could the rough roads (and we hit some pretty rough roads, especially 95 in SC) have caused this or is it just the way things are with RV roofs?

2. The manual says only use either "5160 Alphathane non-sag" or "5121 self leveling" sealants. Does it matter which one I use? Should I clean around the area and apply new sealant on top of the old? The existing sealant is not loose in any way. Pictures attached.


Thank you,
Tim

 

[Hoopy Frood]

As much of a pain as it is, I would remove the old sealant and apply new. You might be able to seal it well enough with sealant over the old, but redoing it correctly would give me more peace of mind. But that's JMO of course.

 

[Chaps2018]

My questions:

1. Is this normal for a new trailer (4 months since manufacture)? Could the rough roads (and we hit some pretty rough roads, especially 95 in SC) have caused this or is it just the way things are with RV roofs?

2. The manual says only use either "5160 Alphathane non-sag" or "5121 self leveling" sealants. Does it matter which one I use? Should I clean around the area and apply new sealant on top of the old? The existing sealant is not loose in any way. Pictures attached.

1. I suspect your manual says it is the customer's responsibility to inspect/reseal all surfaces every 90 days. That said, any sealant issue will be "normal" and needs to to be corrected.

In this case, it appears the sealant is peeling back from the vent in that area. However as I look around that area (to the right) there appears to be a trough where it looks to me the sealant may have not been applied properly. It needs to be touched up with sealant. I would recommend you are diligent about inspecting your roof and reseal these sorts of anomalies as required. DO NOT PROCRASTINATE. Water damage is the #1 destroyer of RVs. Water damage is difficult to detect until its too late and is very expensive to repair.

2. The non-sag sealant is for vertical surfaces where as the self leveling is for flat surfaces. I understand your manual recommends Alpha sealants but I just want to point out Dicor Lap Sealant has been the industry standard for some time. It seals well, is durable and it time tested.

I clean with denatured alcohol (also helps with visual inspection as the caulk ages/collects dirt) then apply sealant over the existing sealant. The only time I remove sealant is when doing an underlying repair or it has completely failed. Use the self leveling sealant to encompass the appropriate areas. You will want to make your reseal job visually obvious so that it is easy to inspect as time goes on.

You might find this video helpful. https://www.youtube.com/watch?v=qvQKJiatP-g

 

[Chaps2018]

While on the subject of roof sealing, I would highly recommend you get a small roll of eternabond roof repair tape for your onboard repair kit.

Between this tape and lap sealant you can manage any mishap that tears or pokes a hole in your roof membrane. I would suggest that its not a matter of "if" but "when" you scrape a branch, back into a branch, etc.

These products are very robust and will likely last the life of your rig should you need to make repairs.

 

[retired_engineer]

- snip -

2. The non-sag sealant is for vertical surfaces where as the self leveling is for flat surfaces. I understand your manual recommends Alpha sealants but I just want to point out Dicor Lap Sealant has been the industry standard for some time. It seals well, is durable and it time tested.

- snip -

I used Alpha sealants on a previous trailer that used Alpha's membrane. My experience with Alpha sealants was they didn't stick very well and as a result I was spending quite a bit time replacing lifted sealant. Towards the end of our second season I switched to using Dicor sealants and the sealant life went from months to years. In talking with others it does not sound like I was the only one to run into this.

 

[Hoopy Frood]

FWIW, I've had good luck with the Alpha sealants. They tend to be harder to find than Dicor sealants.

 

[Riverbug]

Naturally, you can do what you want. I started RVing in 1990 in motorhomes and the technology for the roofs has not changed much. The Dicor and similar products have always been inferior and always needed routine maintenance. Even our 2022 and 2023 RV's needed maintenance within the first two weeks. the MLE leaked inside during the first rain. Part of the issue is the roofing products used and the other part of the problem is poor application by the manufacturers. Check along the rear top trim piece and see if there is any cracking/gap in the sealant where the trim meets the roof. The product is often applied so thinly that it cracks and separates after the first couple trips, if not by the time you have it home. The gutters and awning also seem to be problem areas.

My approach for years now has been to take a page out of the marine book. Why can we caulk underwater and above water fittings without worrying about them leaking for years? But you can't go 3 months on an RV without the threat of missing a new leak? Materials and application. As I find areas needing maintenance, I remove the old OEM materials and replace with marine adhesive caulking. If I felt like taking the time, I would do everything at once and be done with it. But I tend to do it as I have time or need to. My go-to has been 3M 4200 or 3M 4200UV. I use white for 90% of the areas. I don't care if I have white on black for the most part as most of the RV is white/black. The front is the exception where the trim and front are black on black (on ours anyway) so I find a black adhesive caulk.

4200 is good because it is very strong for bonding and adherence but can be removed with some effort. 5200 is not good for this as it is permanent and you don't want that unless you know it will never be taken off. The UV version will not yellow so using that in visible areas is good, but on the roof it doesn't matter so much. So why don't manufacturers use similar stuff? I can't say but assume ease of use and cost. Adhesive caulk is not forgiving. It's messy and takes a bit of practice. The roof is a great place to start for that reason. It adheres well to roof material as well as Dicor. In a pinch you can cover over Dicor if needed but I like to take it down to the membrane clean it and know that I won't have to do it again for years. (Doesn't mean you don't still need to check things over once or twice a year though.) Regarding cost, a 10oz tube of 4200UV runs around $25 compared to alpha systems self leveling caulk which can be had for less than $10.

I don't know why but every so often I get on this soap box in the forum. Can't help myself. Okay, I'm off now.

 

[Hoopy Frood]

Naturally, you can do what you want. I started RVing in 1990 in motorhomes and the technology for the roofs has not changed much. The Dicor and similar products have always been inferior and always needed routine maintenance. Even our 2022 and 2023 RV's needed maintenance within the first two weeks. the MLE leaked inside during the first rain. Part of the issue is the roofing products used and the other part of the problem is poor application by the manufacturers. Check along the rear top trim piece and see if there is any cracking/gap in the sealant where the trim meets the roof. The product is often applied so thinly that it cracks and separates after the first couple trips, if not by the time you have it home. The gutters and awning also seem to be problem areas.

My approach for years now has been to take a page out of the marine book. Why can we caulk underwater and above water fittings without worrying about them leaking for years? But you can't go 3 months on an RV without the threat of missing a new leak? Materials and application. As I find areas needing maintenance, I remove the old OEM materials and replace with marine adhesive caulking. If I felt like taking the time, I would do everything at once and be done with it. But I tend to do it as I have time or need to. My go-to has been 3M 4200 or 3M 4200UV. I use white for 90% of the areas. I don't care if I have white on black for the most part as most of the RV is white/black. The front is the exception where the trim and front are black on black (on ours anyway) so I find a black adhesive caulk.

4200 is good because it is very strong for bonding and adherence but can be removed with some effort. 5200 is not good for this as it is permanent and you don't want that unless you know it will never be taken off. The UV version will not yellow so using that in visible areas is good, but on the roof it doesn't matter so much. So why don't manufacturers use similar stuff? I can't say but assume ease of use and cost. Adhesive caulk is not forgiving. It's messy and takes a bit of practice. The roof is a great place to start for that reason. It adheres well to roof material as well as Dicor. In a pinch you can cover over Dicor if needed but I like to take it down to the membrane clean it and know that I won't have to do it again for years. (Doesn't mean you don't still need to check things over once or twice a year though.) Regarding cost, a 10oz tube of 4200UV runs around $25 compared to alpha systems self leveling caulk which can be had for less than $10.

I don't know why but every so often I get on this soap box in the forum. Can't help myself. Okay, I'm off now.

I, for one, like to hear differing opinions on subjects such as this. As long as they aren't presented as the ONLY route to take. You've presented your views in an even handed manner. Thank you.

 

[Riverbug]

I, for one, like to hear differing opinions on subjects such as this. As long as they aren't presented as the ONLY route to take. You've presented your views in an even handed manner. Thank you.

You're very kind, thank you.

 

[Chaps2018]

The marine product appears to be robust. I assume you verified compatibility with the roof membrane.

Alternately, I have used Eternabond tape on the front cap/roof and rear wall/roof joints. They are notorious for leaking as you note.

You mention the gutters and awning…I am having trouble tracking down the source of those leaks.

I also see the thin sealant issue you mention along the sides where the roof/ side wall joint. I have seen folks wrap Eternabond tape from roof down to the side trim. Have you tried the marine sealant along the sides as well?

 

[Riverbug]

The marine product appears to be robust. I assume you verified compatibility with the roof membrane.

Alternately, I have used Eternabond tape on the front cap/roof and rear wall/roof joints. They are notorious for leaking as you note.

You mention the gutters and awning…I am having trouble tracking down the source of those leaks.

I also see the thin sealant issue you mention along the sides where the roof/ side wall joint. I have seen folks wrap Eternabond tape from roof down to the side trim. Have you tried the marine sealant along the sides as well?

Probably not compatible according to the manufacturers but I am not concerned about that given the inferior products they find compatible. Adhesive caulk doesn't eat through the material, it adheres better than the products they use, and it has lasted several years in my experience.

Yes, I use the adhesive caulk for just about everything on the outside. What's nice is that it can be layered or glopped on and spread as needed, or small/thin layers as needed. But I admit it is challenging to get a nice smooth finish. When re-doing the top trim I run a line of masking tape about a quarter inch in from the top edge outward. That way when I am done laying down the caulk I pull the tape up (toward the roof while it is still wet) and have a pretty smooth edge without it going over trim edge where you can see it from the ground. I say pull it toward the roof because it is very sticky; pulling it toward the roof a bit will ensure it falls onto itself rather than over the outside edge. For things like the hardware for solar panels, I caulk the screw holes, screw down the feet, mask the area with tape then lay up caulk over the entire foot so that it is completely sealed. You'll have a very hard time removing this stuff from a rubber type roof without tearing it. If you do tear it, you can spread caulk over the area and it will be just fine as it adheres just as well to the wood underneath. I do not use it for things that may need regular removal, it's just too hard to remove if you want to check for water line connection leaks for something. But things like water heater, lights, trim, etc., I always use it.

In the past, I also had very good luck with Eternabond tape but personally find adhesive caulk to be more flexible and adheres better over screws and other things (such as self leveling caulk-when it cannot be removed in a pinch or laziness).

Regarding the awning and gutters...I suggest re-caulking the usual areas, then remove the screws/bolts one at a time, put some caulk in the hole, and replace the screw/bolt. Just do them all and that will save you headaches down the road. On the side trim, I caulk the edges as normal, pull the vinyl trim that covers the screws, caulk the holes and put the screws back in. Often you'll find some of the screws already show rust, which means there has been water getting to them. I find this is easier to do now that I'm retired, but it still take alot of time, and a challenge when we travel months at a time.

 

[Texdan]

Not to hijack this thread but had an accidental roof scraping from a low car port and wondering how to fix it? Eternabond tape, self leveling caulk, ? 2020 Grand Design 29RS. Thanks.

 

[Chaps2018]

If it were mine…

1-I would want the torn roof membrane to be as flat as possible before patching with eternabond. So, I would either glue it down, cut off the parts that won’t lie flat, etc.

2-apply a single eternabond patch to cover the entire opening. The starting edge would be the top of the metal edge on the vertical side.

3-apply Dicor lap sealant to the edges of the eternabond patch. Sides and top of the patch. This will result in a bullet proof seal that will likely last the life of your camper.

An example, while not the same roof line, you will get the idea

 

[Texdan]

Thanks! I was hoping this would be the way to go. Luckily we are parked under a carport so I have time to fix it without worrying about rain!

 

[jlk111]

Thanks! I was hoping this would be the way to go. Luckily we are parked under a carport so I have time to fix it without worrying about rain!

I would lap the Eternal bond tape into the gutter about 1/8 inch from bottom of gutter to prevent wicking. You could paint the tape black along the current black roofline to match both ends. I feel it would prevent one edge from ever coming loose without being spotted from ground. My $.02.

 

[Texdan]

Is this the right Eternabond? It says if for rubber roofs so does it work on the GD roofs? Thanks.

https://www.amazon.com/gp/product/B003RW29FW/ref=ox_sc_act_title_4?smid=A2PK7117F7TKMV&psc=1

 

[Riverbug]

Is this the right Eternabond? It says if for rubber roofs so does it work on the GD roofs? Thanks.

https://www.amazon.com/gp/product/B003RW29FW/ref=ox_sc_act_title_4?smid=A2PK7117F7TKMV&psc=1

I'm always skeptical of fakes on Amazon. The picture doesn't look right to me, but I don't know. If you look at others they have the Eternabond label that you would see on a store shelf (I know, they can fake a label too).

 

[Texdan]

I'm always skeptical of fakes on Amazon. The picture doesn't look right to me, but I don't know. If you look at others they have the Eternabond label that you would see on a store shelf (I know, they can fake a label too).

I agree, going with the 'good' stuff! https://www.amazon.com/gp/product/B002RSIK4G/ref=ox_sc_act_title_1?smid=A2PDLNP7KSJHNM&th=1

 

[Riverbug]

I agree, going with the 'good' stuff! https://www.amazon.com/gp/product/B002RSIK4G/ref=ox_sc_act_title_1?smid=A2PDLNP7KSJHNM&th=1

Yeah, looks more legit to me.

 

[Hoopy Frood]

JMO, but just because it says "Eternabond Store" may not mean it truly is the real deal. Amazon is pretty reputable, but they aren't perfect. That being said, I would likely buy it, if I needed that much anyway.