Forum Discussion

WNJeffers's avatar
WNJeffers
Explorer
Apr 23, 2023

Fiberglass roof crack repair

I found a short crack opened up across a small gap between two vent holes cut in the fiberglass roof of my motorhome. It runs from a corner of the refrigerator vent to the corner of a kitchen overhead vent with a Fantastic Fan. Crack is less than 2 feet long. I’m trying to figure out how to best repair it.

My first thought was laminating fiberglass cloth in epoxy resin over the crack. (I have some experience years ago with fiberglass work with boats.) I worry that this could perhaps create a hard spot that may lead to future issues.

My other thought was to simply use Eternabond tape (perhaps a couple of layers in different widths) to seal over the crack but not create a hard spot.

What have others done? Any success stories to share?

Thanks!
Wayne
1997 Safari Sahara
Class A
  • Horsedoc's avatar
    Horsedoc
    Explorer II
    Apr 23, 2023
    Eternabond works great with the fiber backing. Sealed the roof/wall seams on a 2000 Itasca years ago. Then painted the tape with their liquid sealer. Worked great. the fiber backing allowed the tape to flex and seal on corners without the kinks. Was still holding when we sold the coach in 2008. good stuff
    I used a 2" square on the awning that was attacked by an limb. No ripping or tearing from the wound.
  • Gjac's avatar
    Gjac
    Explorer III
    Apr 24, 2023
    Does the crack go through the entire laminate or is it just a surface crack in the gel coat outer surface?
  • oldave's avatar
    oldave
    Explorer
    Apr 24, 2023
    I doubt the crack shows from the ground and running from one opening to another it's not going to keep going so I would use Eternabond. Eternabond will last longer than the RV, no need for 2 layers, but clean & roll it down really well.
  • johnhicks's avatar
    johnhicks
    Explorer
    Apr 25, 2023
    Using Eternabond primer really helps, plus you need a lot of pressure on a hard roller to get it to bond properly.
  • WNJeffers's avatar
    WNJeffers
    Explorer
    Apr 25, 2023
    The crack goes completely through the fiberglass layer, but I cannot see anything structural about the glass layer in the area of the crack. There is plywood underlayment with the relatively thin fiberglass roof sheet on top. (In contrast, the front and back end caps are clearly rigid fiberglass made in molds.)

    My own inclination is to glue or fasten the fiberglass to the underlying plywood along the crack and apply Eternabond tape. I am not sure why it cracked to begin with, but I figure there may have been some movement along this little neck that contributed to it.

    Thanks, everyone!

    Wayne
    1997 Safari Sahara 3540
  • oldave's avatar
    oldave
    Explorer
    Apr 25, 2023
    On my 03 Monaco Windsor the fiberglass roof just floats on top of that plywood
    It may be ok to put some screws or glue there but I probably wouldn't. Those would tend to lock down the area where it needs to be able to move, which might result in another crack in the same area. Eternabond will allow a little movement.
    My guess is it cracked because there was stress in that spot or area. It finally cracked which relieved a great deal of the stress, maybe all of it.
  • WNJeffers's avatar
    WNJeffers
    Explorer
    Apr 26, 2023
    oldave wrote:
    On my 03 Monaco Windsor the fiberglass roof just floats on top of that plywood
    It may be ok to put some screws or glue there but I probably wouldn't. Those would tend to lock down the area where it needs to be able to move, which might result in another crack in the same area. Eternabond will allow a little movement.
    My guess is it cracked because there was stress in that spot or area. It finally cracked which relieved a great deal of the stress, maybe all of it.


    I think the fiberglass just floats on top of the plywood on mine, too. Good point about not locking it down where it may need to be able to move.

    Thanks!

    Wayne
    1997 Safari Sahara
  • Bruce_Brown's avatar
    Bruce_Brown
    Moderator
    Apr 29, 2023
    If it were mine I'd drill a small hole at the end of the crack - they'll keep it from growing, then I'd probably Eternabond it.
  • Rick_Jay's avatar
    Rick_Jay
    Explorer II
    Apr 29, 2023
    As others have said, since the crack can't spread any more, just use Eternabond. It's great stuff. Applied properly you'll never have to worry about it again.

    Good Luck and let us know how you make out with the project.

    ~Rick

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