Preventing RV Roof Leaks (Dicor Maintenance)

TheRVgeeks Annual Maintenance, Maintenance, Repair 24 Comments

Just about everything attached to the roof of an RV is a potential entry point for water. The TV antenna, vent fans, satellite dish, plumbing vents, solar panel mounts or anything else screwed into, or transitioning through the roof to the interior are places that invite leaks.

The main line of defense against water damage is vigilance — periodic inspection of the Dicor waterproof sealant. Dicor self-leveling lap sealant is ubiquitous in the RV industry, sealing roofs on everything from pop-up trailers to diesel pusher motorhomes and everything in between.

The best way to avoid ever developing a leak in your RV is to check the roof at least a couple of times a year, looking for any cracks in the Dicor. One of the surest signs that an owner is meticulous in caring for their RV is to look for the tell-tale signs of Dicor patching on the roof. Dicor develops small cracks over time, and the periodic application of fresh Dicor to cover those cracks leads to the patchwork look of a well-maintained roof.

Dicor is available at just about any camping supply store or RV dealer, and requires only a standard caulk gun to apply. Before applying new sealant, just clean the area to be patched with mineral spirits. We have a fiberglass roof but if you have a rubber (EPDM) roof, it’s OK to clean the Dicor with mineral spirits. Just go easy on the quantity, being sure not to soak the rubber.

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Comments 24

  1. Hi Guys! What product do you recommend to seal other parts of the RV. For instance, around the lights or receptacles on the side on the RV. Thanks!

    1. Post

      Hi Chris! We generally recommend that you contact your manufacturer to ask what they use in that application. Seems like they all have their own preference… or engineering need based on flex, etc. Barring being able to do that, we like ProFlex Clear Sealant ( for sealing things on the sidewalls. It’s clear AND UV-stabilized, so it will last. And since it’s not silicone, it doesn’t cause problems with preventing anything else from sticking. The only down side is that it’s not quite as “friendly” to work with as a pure silicone caulk would be, so it takes a little bit more care when applying it (we recommend using painter’s tape to mask off the area so that you can apply the ProFlex, then immediately pull up the painter’s tape to leave a nice clean, smooth edge). Hope this helps!

  2. Great post as always guys!! I also have a fiberglass roof that I clean every six months or so and then seal it with 303 protectant. I do notice that as years go by i can’t get it as sparkling white as the previous cleaning which drives me nuts. Do you guys ever reseal your roof with elastomeric paint or another coating from time to time?

    1. Post

      Thanks, Mark! Sounds like you’re doing more than we do, as we don’t put anything on our roof. We used 303 once, and didn’t like how slippery it made it… we’re up there too often and it was dangerous. We just power wash ours regularly and get it as clean as we can with regular car wash. We’ve never considered any kind of coating, as we’re not convinced it won’t end up requiring more upkeep over time… and we can live with a not-quite-white roof! ?

  3. Hello RV Geeks, I’m a New to the RV world and I am learning a lot from your videos. I really appreciate them! In one of your episodes that you covered replacing the roof wood after a leak and you stressed inspecting all of your joints and seals for possible leaks.

    Now, I’ve read several articles and watched many videos regarding this same subject. But it occurred to me that no one has ever done a video of what some of the signs would be if a joint or seal was leaking. Although this might be a tough thing to do, would it be possible to make a video covering how to inspect the roof/side joints and seals and things to look out for when inspecting.

    Thank you.

    1. Post

      Hi Gary! The only signs we’re aware of that leaking is occurring are water stains on the interior walls of the RV, or softness in an area of the roof. The latter symptom is how the owners of the RV in the other video realized that there had been water penetration. We’re quite certain that because they had only owned the rig for a short time, it was very well underway during the time the previous owner had the rig. The best thing to do is have a professional pre-purchase inspection done (which theses buyers did do, but it was apparently missed). It can be an insidious problem, and the inspection and touch-up steps we’ve outlined in this video have kept us dry for over 13 years in our Mountain Aire.

    1. Post

      Hi Ken,

      We haven’t had to do this on our RV, but we’ve asked Newmar specifically what we SHOULD use and they told us “Dow Corning 999 Clear Silicone Sealant”. So our first suggestion would be to contact your manufacturer and ask them. Silicone is common, but so is ProFlex… and there could be other sealants that we’re not even aware of. If you can’t get an answer out of your manufacturer, you could also try posting that question to the appropriate brand forum over on It’s free to join, free to post, and there’s likely someone out there with your exact coach who has already tackled this project.

      Sorry we can’t be of more help!

  4. Just watched the video on checking the roof seals.
    How do you know when it’s time to remove all the dicor and start over again with cleaning and reapply new sealant?
    Tks for the info

    1. Post
      1. Thank you for the reply.the wife and I are working on getting our first RV.we’re learning a lot from your videos.
        Thank you and keep up the great videos.

  5. Glad to see you mentioned EternaBond, after watching
    I decided to remove all my Dicor and replace with EternaBond.
    WOW, so much better.
    Have you considered doing that?

    1. Post

      Hi Nyle! While we also love Eternabond, we’ve never taken the time to replace our Dicor with it. But it’s a great idea in many places. Just be sure you’re careful about using it in any spots where you might want to remove it, such as around an antenna that could break or fail and need replacing at some point. Because the “Eterna” in the name is no joke. It will NEVER com off! ;-)

  6. I have a 2006 bounder that needs roof maintenance. The roof seems to be rubber, how do I clean it and what products should I use, I bought it used and don’t have all of the paper work.
    I have two slide out, one on the bedroom and a big one behind the driver,I now have a leak that seems to be coming from the driver side and when it rains water floods the top of the big slide out and then runs out into the inside of the coach, although when I pull the slide out this does not seem to happen. Do I need to replace the slide slide outer seal?. Your help is greatly appreciated, I enjoy all of your videos. I live in southern California and rarely rains, but when it does, I have this problem.
    Thanks a lot.

    1. Post

      Hi Rick,

      While the term “rubber roof” is commonly used for anything that isn’t fiberglass, your Bounder most likely has a TPO or EPDM roof. You want to be careful using anything that could damage the roof material itself… or which could penetrate through the material and affect the adhesive bonding it to the roof.

      Typically, you’d need two products to accomplish the task: a cleaner and a conditioner (adds moisturizers and protectants to keep the material from degrading). It’s been a long time since we had an EPDM roof (on our 2002 Bounder Diesel), so we don’t have any current recommendations for products. Anything you can pick up at your local RV supply store should work just fine (Camco, Thetford and Dicor brands are widely available). But if you want to be extra careful, it couldn’t hurt to call Fleetwood and ask if they have recommendations for your roof.

      As far as the slide seal, it sounds like it could one of two things causing it to allow water to enter when the slide is closed:

      1. The slide could be out of alignment and therefore not properly sealing against the sidewall when closed. Check to see if it looks flush from the outside when you close it… and if the gaps around the edge look even. Not sure what the alignment procedures are like on your Bounder (you can either Google them or look on the forums) or take it in for service to a Fleetwood repair location.
      2. Like you suggested, the outer seal on the slide could be failing and needs to be replaced. Installation techniques vary, but most often they’re just stuck on with adhesive. You’d want to be sure you completely remove the old seal and thoroughly clean the surface before installing the replacement.

      Hope this helps!

  7. I am about to reseal my 2000 Fleetwood Southwind roof.
    Should I consider the extra expense of pulling the AC units to replace the gaskets?

    Great work guys. Excellent presentations.

    1. Post

      Hi David. We’re gonna go with the “If it ain’t broke, don’t fix it” school of thought here. Personally, we would never consider taking such an extreme step unless signs of water leakage were evident. Disturbing the A/C unit unnecessarily could lead to a lot more problems than leaks!

  8. What about bubbling? I had the roof worked on (professional) last Fall and when I inspected it today, I see bubbles (air pockets?) on one of the front corners where the roof meets the body of the coach (Class A). Should I touch that up with Dicor or is that normal?

    1. Post

      Hi Nadja. We assume you have a rubber roof (TPO or EPDM)? That’s tough to diagnose without seeing it. How large are the bubbles? Like dime sized, or larger areas? From your description, it sounds like it’s possible that whoever did the repairs didn’t get proper adhesion between the rubber material and the underlying roof structure. Are you nearby this tech so that you can have them inspect it? If it’s separating due to improper adhesion, it’s probably not a big deal, especially if the bubbles are small and don’t spread more over time. But if it’s due to water penetration, that should be addressed ASAP. If that’s the case, determining where the water is getting in is key. If the person who did the work is not available, you should have it inspected by someone else as soon as you can.

  9. Wondering if you have a video on fixing a leak that is coming through the vent on the front AC unit. After a hard rain I get a leak through the vent for about a full day. I have tightened the 4 bolts as much as I feel comfortable with but that has not solved the problem. Hopefully I don’t have to remove the AC unit to solve the problem.

    Searched for something on your utube site but haven’t found anything.

    1. Hi Gerry. Since your leak appears only after a hard rain, it’s obviously not coming from the A/C unit itself (i.e. condensation). Finding a leak can be a real challenge, since water can run along inside the RV (in ductwork for example) and drip somewhere other than the exterior entry point. But since your leak is coming in at a known point of entry from the exterior (the AC unit) that narrows the most likely suspected area down to the unit itself. Unfortunately, it’s difficult to see where the AC unit meets the roof, so therefore difficult to check the seal. You may have to remove the shroud and see if you can spot the point where the unit meets the roof, so that you can check for cracking or other suspected sealant failure. But we suspect that the unit may need to be removed, which we’ve never had to do before. We’d suggest that posting your question on the iRV2 forums would be very helpful. Someone there is surely more knowledgable than we are about this topic. It’s free to join the forums and post: Sorry we’re not able to be of more help here. Please let us know how you make out.

      1. Thanks so much for your reply. I have searched at length on Irv2. Read everything I could find and suspect that I will have to remove the AC to trace this down.

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