Underbelly protection

[Modstock]

I thought we could discuss underbelly protection. Noticed on some newer trailers that they have some sort of black cloth or plastic to cover up the underbelly.
While researching the matter, it was brought up that some use Coroplast sheets.

I noticed my insulation underneath got pretty tore up from some of the dirt roads/gravel and im due to paint the frame soon. The factory paint didn't do much and starting to show surface rust. Already had to repaint the tongue.

Has anyone here added any underbelly protection ?

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[Wrecit]

My build is base is a 37 year old trailer. My blood iron count has probably doubled from all the rust lol. I pulled the floor then used bedliner as a new undercoat and also painted the new floor underside with it.

[tony.latham]

I use epoxy to seal the bottom of the floor. Nothing seals like it since it soaks into the wood a bit and plasticizes it. I've never noticed any damage to a floor treated with it.

I don't recommend putting a sheet of something or other on the floor because if water gets underneath, it'll just sit there.

Noticed on some newer trailers that they have some sort of black cloth or plastic to cover up the underbelly.

That's the RV's answer to get the "product" through the three-year warranty as cheaply as possible.

Tony

[Staryder61]

Not sure about others, the trailer I bought was a Interstate Trailer. When I researched them before buying.
Found out they use a asphalt based undercoating under the type of trailer I bought.. When I checked it out,
It was coated heavy on the under belly plywood and even the frame was coated heavy.. So we'll have to see how it holds up..
Our trailer will not be pulled off road for long distances like some are..
Most of our traveling will be on paved roads,
where construction is happening, gravel, chip and seal roads. Things that are normal..

Coroplast.. I think would chip and crack after awhile.. letting moisture in and holding it there.. depending on the type of application used..

Now Halfway Danny,, uses plastic laminate on the bottoms of his..
see his post here..
viewtopic.php?f=2&t=74899&p=1292925&hilit=plastic+laminate#p1292925

And I have to agree with a couple things Danny says.. laminate and contact cement creates a very tight water seal.. has been used on kitchen and bath counter tops for years and years..

But that said, that doesn't help with the metal frame under the trailer.. or the insulation..

[JasenC]

If it's not bonded to the ply it's a bad idea. As already stated, it'll trap moisture.

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[Modstock]

Well, what could I do to help protect the 1" insulation underneath.. Or should I replace it every few years ?
I have the silver side facing down.

Did add some mudflaps that should reduce the gravel.

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[Staryder61]

Mod,
hopefully the mud flaps will help some.

Is the insulation that's getting hit by the rocks in front of the trailer axle?
Or all over?

Thought I'd throw this out to the group.. what if laminate, FRP or the coroplast was attached under the trailer, to protect the insulation from getting eat up by road dirt and gravel? Not as to seal it, water could get in between the insulation and what ever was used, but it would also let the water out..
the laminate, FRP or coroplast would not be against the wood..
Only other way, is to redo the insulation and of course the paint every couple years or so..

[Modstock]

That's what im going for, protecting the insulation (not seal it) . Could always leave it a bit short on the sides to allow water to drain.
Keep in mind I live in a desert and driving in rain is kinda rare here also gets stored in a garage during winter.

The insulation is getting tore up pretty much all over, more so in the front.

Gonna put the trailer up on ramps this weekend to repaint the frame. Pics soon.

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[Wrecit]

If you laminate with FRP do not trust adhesion to just adhesive. You will need to run at least washers and screws which will penetrate the water tight seal. To counter this run the screws in then remove and fill the hole with a good silicone then run screws back in.

The reason is FRP will have a bit of weight and if even a small corner breaks free it will eventually work it's way free. A chunk of foam board breaking off going down the highway is annoying to other drivers. A chunk of FRP will just about insure an insurance company getting involved (yours if they get your plate number)

[Staryder61]

Very good point Wrecit..

I just remembered, someone on here used fender washers and screws, to attach their insulation..

Why couldn't that also be done with the FRP or laminate, and right across the front,.
use the fender washers and screws going through a 1" x 1" aluminum angle to secure it over the edge of the FRP, laminate and insulation..
the aluminum, wouldn't be to seal the water out, but with the help of the angle and the screws and washers, it possibly would keep the air flow from breaking off the FRP, laminate..

I'll retire back to my corner now,

[Staryder61]

Modstock, whatever you do.
I would be interested on an update.. seeing, how I'm still working on my trailer at this point..

[dmdc411]

While building my floor, I figured anything I did above and beyond quick coat of color was way more than my 16yo popup had. And it's floor was rotted in the corners, and two joints! It appeared to have a coat of black on the osb. So, two coats exterior primer, and paint! The td has been on the road for 8 yrs think? Towed through a few torrential rain storms, not a leak, no cracked or peeling on the under side! My thoughts? Let it breathe, protect it (the entire camper) from moisture from above. That's where the damaging moisture comes from.

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[Modstock]

The gravel damage wasn't as bad as I thought but it wasn't where I thought it would be.
The most damage was from the axle back. Maybe gravel hitting the axle and bouncing up .

I need to redo the very rear insulation. Also have an idea about protecting it in the future. Involves no drilling, some K-tex material and electrical conduit.
Water shouldn't get trapped cause there will be gaps between it and the insulation.

Front views.
You can see a gash in the center.




Rear.


You see the holes in the bracing. I could sew up a k-tex sleeve with 2 loops, each section and run conduit through to hold em up.
I should be able to get it tight enough.
Sewn up enough dump truck covers in my time.

While under there the frame got sanded, wiped down with wax&grease remover, then brake cleaner.
And painted with 2 cans of VHT chassis paint.
Tested on the tongue and holds up good.


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[Wrecit]

Actually the damage area makes a lot of sense when you think about it. The fenders on a trailer are intended to help divert rocks, ect downward so they don't pop up and hit other cars. The rocks your tires are kicking up are bouncing off the road and hopping up to rip up your rear insulation.

Not positive it will help but some form of mud flap on your trailer may reduce damage.

[Modstock]

Yeah, I was thinking of just replacing those rear sections to see if any improvement.
Most of this is from the jeep with dinky mudflaps and mud tires.

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