Material question - fabric under trailer

Sorry to hear this, from what I've seen on this forum over the years I hope my RV never springs a leak.

I started pulling the underbelly apart last night and salvaged nothing. I'll need to replace part of the trailer floor as it looks like moisture was being trapped between the vinyl floor and Darco. I'm opening it up to let it get airflow and will be fixing the trailer from the roof down.

Marine plywood and unddercoating was my original plan as well. It seemed to make sense, but I wasn't sure what it's purpose was. If I can salvage what I have it seems tough and light. I also used to do signs and have a local source for 4x8 sheets of coroplast. It's been raining for the last few days and I haven't gotten to take it out yet, but I'm hoping to do it tomorrow.

It sounds like the same material I had in the wheel wells of my 5'r. Tire blow-outs, last year, tore the stuff up pretty bad and exposed some water lines, etc. I replaced it with thin marine plywood and then covered it with the spray undercoating from the auto parts store. Seems to be holding up nicely.

Thanks!!! It looks like it's Darco. I punched a hole in it yesterday to drain water, but I see they sell seam tape as well. I'll try to salvage it, but at least I know what it is now if I need to replace it.

Sounds like you are talking about Darco Darco I would replace it when done.

The covering that posters are referencing above is probably Coroplast (plastic cardboard) that manufactures use as a second floor for an insulated underbelly. Coroplast

A typical underbelly would be wood, insulation(sometimes) Darco,then holding tanks.

A typical insulated underbelly would be wood, insulation, Darco, holding tanks, insulation, then Coroplast

It's called rodent barrier in the trade. It's also a vapor barrier and very durable. If you can salvage it then it's desireable to keep it. The plywood will probably work but I would be concerned about it getting soaked during wet travel and staying that way a long time. Could be a mold issue.

The black plastic sheeting is the best method for sealing up the bottom. I would carefully remove it fix the problem and then replace the plastic and use adhesive and screws to hold it in place and seal the new seams with silicone.

I think almost all of the larger trailers have the underbelly fabric in place. Helps with keeping the tanks from freezing up and keeps all of the road trash from building up under the trailer.

Sure is pain when you have wiring projects...

I found a couple of places where I had alot of wiring in one place and cut me a weather tight trap door there... As you probably have found out already there are a pretty good number of screws to remove the plastic...

I think you will want to put it back when you get done with your rebuild items...

My trailer floor uses the 3/4-inch OSB flooring and I have some kind of black sealant on the bottom side. This is under my POPUP which does not have the under belly membrane installed.

Roy Ken

Thanks for the reply. I'm going to pull it out tonight to get a good look at it (assuming the rain holds off).