Why You Should Use Dicor to Seal RV Seams

Preventative maintenance is important to keep your RV in the best condition possible. Many such tasks are not as difficult as they are tedious and time consuming. But the alternative is an expensive trip to the shop to get it done—or worse yet, an even more expensive trip if you don’t do them! Case in point: re-sealing the exterior seams on your RV.

Previously, I’ve described How To Replace Exterior RV Weather Molding. Recently, I took the time to remove and replace all the Dicor used to seal the seams on our exterior walls, roof and trim.

Why Dicor Instead of Caulk?

On our previous rig, I had once used silicone caulk to seal an exposed area of trim that was allowing moisture into the wooden wall. I regretted that later when I had to remove it and do the job right.

No silicone caulk on RV trim!

Do not use silicone caulk on RV trim.

Yes, silicone caulk is waterproof. But it will eventually dry hard and crack over time. And it is a serious bitch to clean off!

Dicor Lap Sealant will never harden. It remains flexible and water-tight as it ages. It can, however get ugly and dirty, and after many years it may have a tendency to shrink and separate. That’s why it’s important to frequently inspect all exterior seams—around all trim and any vents or light fixtures.

Re-seal old Dicor Lap Sealant DIY RV Maintenance

Aging Dicor can get ugly.

Depending on the RV manufacturer, Dicor is often applied rather sloppily. Once you are fed up with the droopy looking brown goop, take the time to remove it and replace it with the right stuff.

Re-seal old Dicor Lap Sealant DIY RV Maintenance

Clean off all old Dicor to ensure good seam with new sealant.

Caulking tools or some sort of dull plastic blade is great for removing the bulk of any old Dicor. Use a rag or sponge and some alcohol to get rid of remaining residue.

Re-seal old Dicor Lap Sealant DIY RV Maintenance

Clean trim ready for new Dicor sealant.

Make sure you have plenty of Dicor on hand before you get started. I used four tubes to reseal our rig, and always like to have some on hand for any emergency repairs.

dicorWhat Kind of Sealant is Best for RV Trim

Be sure to use the right type of lap sealant too! Dicor is the most popular brand name. It is available in a few different shades, but there are two kinds you want to pay attention to when ordering Dicor.

Self Leveling Dicor is more fluid, it is best used on the roof or flat surfaces where even spreading of the sealant is desired.

Non-Leveling Dicor is best for trim on vertical surfaces since it will not sag as much. Like so…

Re-seal old Dicor Lap Sealant DIY RV Maintenance

Use non-sag Dicor on vertical surfaces to avoid drooping.

See what I mean by sloppy application?

TIP: Use a steady hand with a 3/8″± bead of sealant and apply long smooth strips at a time. Do not try to smooth out the sealant with your finger, as you might when applying caulk. Before it dries, Dicor is very sticky!

Resealing the trim on your RV is a time consuming job, but the reward is a clean looking rig without the potential for water damage.

Re-seal old Dicor Lap Sealant DIY RV Maintenance

Clean water-tight seam with new Dicor lap sealant.

Any Questions?

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17 Responses to “Why You Should Use Dicor to Seal RV Seams”

  1. Can Dicor 551LSW be used for horizontal & vertical trim seams on the sidewalls?

  2. Hi Jim, I’m planning on resealing and coating my 2008 Winnie Access WF29T roof with the Dicor Fiberglass roof coating. You mentioned the Dicor Lap sealant is for EPDM and TPO sheeting but there website says it sticks to Fiberglass. Have you seen less then satisfactory results there or do you feel there product will work/stick well on fiberglass roof material?

  3. Donald K. Laing Sr. August 10, 2020 at 11:26 am Reply

    You did not mention any additional tooling to the freshly applied sealants? Should you or can you smooth it out?

  4. what is dicor lap sealant made of is it silicone or some type of edpm..I am getting ready to remove some.

  5. Hi there. Thanks for writing this article. Any tips for how to remove layers of goopy Dicor on the upper corner trim on my travel trailer? It looks like my trailer has some weird growth on the top.

  6. Hi Jim,

    What method you recommend to smooth the dicor bead?


    • For best results, the least messy method is to not smooth the bead at all. Just apply an ample consistent amount. When necessary, I have found a moistened finger works best.

  7. Hey Jim. What do you think about the trim typically facing front or rear that has the long vinyl piece covering the screw holes; in respect to whether it is water-tight or not? My vinyl shrunk and ripped loose from the screw “designed” to keep the vinyl in place. I am thinking taking off the vinyl and fill the groove/ screw hole … I need black. I just found your site and was just reading Rene’s satanic experiences. What I have heard about working there was a good gig. I realize this was during the dark days of 2009, but awful, huh? The Dicor seam you reworked looks nice.

    • Thanks for the comment Clint! I would replace the trim, and wrote a post all about that: How To Replace Exterior RV Weather Molding

      As far as Amazon Camperforce goes, based on Rene’s experience and what I hear in the Workampers Facebook Group, you will either love it or hate it. Only one way to find out! But the Fernley warehouse is no more, and I’ve heard other locations were managed much better.

  8. Thanks Jim, we can all use your suggestions

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