Dicor, Sikaflex, or 3M - which do you love and why?

Discussion in 'Roof/Floor Repair & Maintenance' started by MIlover, Sep 27, 2015.

  1. MIlover

    MIlover Member

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    Portal folks,

    We need to seal our Fleetwood's roof-mount tracks, and also the corner roof caps. Like many, I've fallen into the abyss of over-analysis after reading too many posts about caulk.

    I've come to the conclusion that Sikaflex 221/715, Dicor self-leveling, and 3M4200 are all acceptable choices; and have learned that self-leveling versions should only be used for horizontal, but not vertical surfaces. Sounds good so far, right? Please tell me which of these sealants you would use for the aforementioned job on your own pup, and why. If possible, I'd prefer one that would work for the roof tracks and corner caps, and am leaning toward Sikaflex 221. But then, I read it tends to yellow with UV exposure?

    Thanks for your opinions!
     
  2. StageLover

    StageLover Member

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    Hi Lover! (Sorry, couldn't resist)

    I use both Sikaflex and 4200 on the boat. Both work very well but, you are right, the Sikaflex tends to become more of a creamy color with UV exposure. I haven't noticed that with the 4200 but it may be because I used the Sikaflex in places like where the chainplate goes through the deck, areas that I tend to inspect more often. My gut feel is the Sikaflex may be a bit more flexible, thus less likely to crack and leak but that wouldn't be an issue with roof racks anyway. It is more of an issue with the chainplates because the sails put a tremendous amount of pressure on the mast and shrouds which causes a lot of flexing of the chainplates. I have had lesser sealants fail in that application.

    That said, I have found 4200 and even 5200 are somewhat flexible so it may be a moot point anyway.

    I've never tried Dicor. There are no truly horizontal surfaces on a sailboat and I tend to use the same products on the trailer as I use on the boat because I am familiar with them.

    All that said, I would probably use Sikaflex, mostly because I tend to use it more often and happen to have a couple of tubes hanging around right now. [;)]
     
  3. Snow

    Snow Well-Known Member

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    I have used Dicor on the roof of the TT for resealing the rubber roof seams, roof vents, antennas, skylight and fridge vent. Works great on flat or nearly flat surfaces.
     
  4. MIlover

    MIlover Member

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    Right back to you Lover. [LOL] Have you used the Sikaflex 715? Does it yellow like the 221 does?

    Thanks Snow. Does the self-leveling Dicor yellow with age? Would you use it on the vertical sides of corner roof caps? The fridge vent must have been a vertical surface, right?
     
  5. StageLover

    StageLover Member

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    Actually, now that I think about it, it is probably Sikaflex 291 that I use. Unfortunately, I don't know for sure and would have to go down to the boat to check a tube. I haven't used 715 so I can't comment on it. However, the Sika website only mentions UV with one product - Sikaflex 505 UV HV. I would assume the other products are susceptible, as are most products in the market.

    Since you are using it as a sealant, thus you want it between the components, and since Sikaflex can be wiped clean before it sets and trimmed after, the color may not be an issue if it is mostly not visible.
     
  6. Snow

    Snow Well-Known Member

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    This was the first time I used the self leveling, but even the original stuff that was on the roof was still a white-ish colour..

    The self leveling Dicor can't be used on vertical surfaces, it is designed to flow and will just run off any vertical surface.. Dicor does have a thicker sealant for vertical use..

    The lower vent is vertical, the upper vent is on the roof.. So far I have only redone sealant on the roof, next summers project will be to start doing vertical seams..
     
  7. billy1

    billy1 New Member

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    I've used Dicor self leveling on my Fleetwood this past summer. It worked great on Vertical and horizontal surfaces. The trick to doing vertical surfaces is to make sure you "tool" the caulking bead after you lay it down, and to not lay down a really large bead.
     
  8. xxxapache

    xxxapache Well-Known Member

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    I use Sikaflex 221 where I need a smooth bead around 1/4". I use Vulkem for larger gaps. I use Parabond for tiny gaps.
     
  9. Barefoot311

    Barefoot311 Member

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    Most manufacturers use Dicor rubber on their campers now so Dicor products are becoming more frequent. Silkaflex is a great product but I have always had a preference to Dicor simply because it has never yellowed on me. Dicors lap sealant will work great on the verticals and the self leveler will do good on the flat
     
  10. MIlover

    MIlover Member

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    Thanks for weighing in everyone. I ended up ordering the Sikaflex 221 for the corner caps, and will use the self-leveling Sikaflex 715 for the roof-mount tracks. I figured we could use both anyway, as vents and other exterior fixtures will need to be addressed at some point.

    I was close to buying Dicor since it seems to be something of an industry favorite, but the supposed "ease" of applying Sikaflex won me over. If you've experienced otherwise, well, I don't want to know!
     

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