Forum Discussion

GPG52_'s avatar
GPG52_
Explorer II
Jan 29, 2018

COUGAR, POLAR PACKAGE -COROPLAST UNDER BELLY

We have a 2014 Keystone, Cougar 327 RES equipped with the Polar Package and totally love it but we do have one concern.
The under belly is covered with what I believe is COROPLAST (corrugated plastic sheets).
On two occasions last year we had to travel for several hundred miles during heavy rain.Once stopped at our destination we noticed an alarming large amount of water coming down from behind the coroplast. On closer inspection we also noticed the coroplast was sagging in some places.
Has anyone experienced similar problems?
Anyone find a fix to prevent water from entering behind the coroplast?
Any fix for the sagging coroplast?
I have asked our dealer to look into the problem and suggested that pieces of light angle iron be placed at intervals along the under belly to support the sags.
Any insight would be helpfull.
GPG
  • GPG52! wrote:
    We have a 2014 Keystone, Cougar 327 RES equipped with the Polar Package and totally love it but we do have one concern.
    The under belly is covered with what I believe is COROPLAST (corrugated plastic sheets).
    On two occasions last year we had to travel for several hundred miles during heavy rain.Once stopped at our destination we noticed an alarming large amount of water coming down from behind the coroplast. On closer inspection we also noticed the coroplast was sagging in some places.
    Has anyone experienced similar problems?
    Anyone find a fix to prevent water from entering behind the coroplast?
    Any fix for the sagging coroplast?
    I have asked our dealer to look into the problem and suggested that pieces of light angle iron be placed at intervals along the under belly to support the sags.
    Any insight would be helpfull.
    GPG


    Put fender washers on the screws when you reinstall the coroplast to prevent breakthrough.

    Here is a thread regarding replacing fiberglass with polystyrene:

    http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25743045
  • If towing in heavy rain, most FWs will get some water inside coroplast. I would cut several 3-sided windows in areas that are lower, to drain water, and check for type insulation. If you have fiber insulation, and it is soaked, it should be removed. Mine has the foil covered plastic bubble insulation, that will not absorb water. If I tow in heavy rain, I later open 3 factory cut 3-sided windows, to let drain/dry out. Mine also came with over size coroplast covers screwed over these 3-sided windows. They are actually designed to give access to tank drain valves.

    Jerry
  • You can use the spray expanding foam to seal around piping and the aluminum tape on seams.
  • Mine looks like the middle off the ocean with huge waves. Its coming off this spring just to inspect under body. Want to check the straps for holding tanks and any other issue
  • My Outback has the same covering on the under belly. I've noticed the seems are not sealed tight at all. There are screws everywhere, including the middle of each sheet, indicating they are screwed into something. I've noticed a bit of sag, but probably not as much as you are describing.

    My guess would be, at one time or another, you've had water get through those cracks when traveling in the rain. The water absorbs into the insulation under there, and that increases the weight. Being enclosed, the water can't evaporate very easy. Next rain, it does the same thing, adding more weight, and then over time, the Coroplast begins to sag, due to the weight now.

    If yours is attached by screws, see if you can remove one panel that sagging and check it out for wetness. If it's dry, then it's sagging, simply because of age. Add a few more screws, or switch it to another underbelly material.

    If it's wet, then with one panel off, you can force air under there and dry all the insulation out. This will take time, but it can be done. Then when dry, replace the panel and take some time to run some caulking along each seam. You'll run through a lot of caulking tubes, but this is about the only way to stop water intrusion from underneath.

    Because it's plastic, I'd probably try Liquid Nails for Projects. This variation of Liquid Nails is maid to use on Styrofoam and won't melt Styrofoam or plastic. Original Liquid Nails will melt some plastics.
  • All coroplast underliners are good for is to hide things they do not want you to see. Pull it on down, but do not be surprised what you find in there. It saves on dumpster capacity at the factory, as well as labor and materials when it comes to attaching wires and such.

    I did as plastic weld on a water tank for a guy once, and pulled a petrified, half eaten bologna sandwich from above his coroplast LOL.
  • Probably water getting in at cracks where coroplast is not screwed down tight or lousy fit. But to be sure...

    1 Pressure test plumbing to psi to what year model your RV is supposed to tested to. If any leaks found, fix. I have one RV that supposed to hold 85 and one that standards are 55 I believe.

    2. If no leaks...think like a rain drop and see where you could get in at. Don't forget wheel wells and drain side of plumbing.

    2. Then Remove that insulation. Replace with foam insulation. Type you have once wet mats up and lays down, never to come back up or insulate right again and will soak up water, little alone ever dry out. (Well maybe 3 months in AZ with fans 24/7) Replace screws with something bigger head to get better grip on coroplast when putting back in, if your screw heads are smaller. Local sign makers sell that stuff cheaper than RV places, if you need any. Foam board not as good as insulator IMO but doesn't care if it gets wet.

    Then seal every crack to seal out water with whatever method you choose. From strong duct tape (gorilla) or (what ever works for you).

    Don't rip out insulation in a mad fit. When pulling it out pay attention to where it is the wettest at, might give you clues to where water is getting in at. Might be nothing more than water getting in where is screwed at sides, but you won't know till you dig in.

    You'll also get to see just what a "polar" package is.

    Just my 2 cents.