Forum Discussion

profdant139's avatar
profdant139
Explorer II
Nov 22, 2015

What thickness of Coroplast for enclosing TT underside?

I'm starting to get serious about adding insulation under my TT, especially under my tanks. (We had our first water line freeze recently, while camping in 11 degree weather.) I am planning to use styrofoam board for insulation, with Coroplast underneath to hold it all in and protect it. I will use self-tapping sheet metal screws, with washers, to fasten the Coroplast to the frame. (By the way, does that sound about right??)

So I went onto the Home Depot site, and they have many different thicknesses of Coroplast, from 0.157 inches to 0.393 inches. Usually, I would opt for the thickest one -- bigger is better, right? But are there pros and cons that I am not seeing? For example, are the thicker pieces more brittle or more prone to sagging?

Thanks in advance for your input!
  • Mortimer_Brewst's avatar
    Mortimer_Brewst
    Explorer II
    Nov 22, 2015
    When I worked on our trailer last year I found that the cheapest place to buy Coroplast was from a sign shop. Prices varied widely, but I was able to get it for about $15 for a 4 x 8 sheet of black Coroplast. The thickness was 1/8". I glued foamboard to the decking above for insulation. I also had to add some crosspieces to have something to screw the Coroplast to. I used 1"x3" lumber for this.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Nov 22, 2015
    well, the thinner ones is the one most TT mfg use. I'd guess our outback is about 1/8".

    I would think 1/2" would be stiffer and less sag, but much harder to work with. the 1/8" stuff can easily be cut with a razor blade and rolled up.

    And Idon't think the thick stuff would add much insulation. I'd go for the thinner stuff and foamboard above it.

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