I had to replace my freshwater tank and repair some wiring in the underbelly of our TT chassis. To do that I had to remove the corrugated plastic cover that they are now installing under most TT and fivers.
When I tried to replace the plastic, I made it about half way to the back when I noticed that the original holes in the plastic were getting further and further off from the holes in the chassis. By the time I got to the back, I was 2" short. I tried again starting in the middle and worked to the front and then the back. Same thing. Does this stuff shrink? Does it make any difference if I don't reinstall it, other than it is a good place for undesirable vermin to set up housekeeping? Maybe it is easier to get a new roll and start over, trimming off what I don't need? Any suggestions are appreciated.
Jayco Eagle HT 23.5 RBS, Ford 2011 Super Crew F-150 3.5 Liter EcoBoost/3.73/Max Tow
I don't know about the shrinkage issue since I haven't had to pull it down and re-attach. Many sign shops use the same type material for a variety of cheap signs and they may be able to sell a short piece that can fill the gap you are dealing with.
Cedar Creek RLSA34, GMC3500HD Duramax
My guess is that there is a bulge in the coroplast (the black stuff that looks like black plastic corrugated paper) and/or the coroplast was changed in orientation when replacing it. Sometimes it seems that the stuff shrinks, but if you work at it a little, you will find that it really doesn't. It's very helpful to have someone else help you by holding up the coroplast) while another person applies the screws. And you might consider putting washers under your screw heads if they aren't there already.
And Yes, you really do need the covering on the bottom of your trailer. If the underbelly is insulated, it keeps the insulation dry. If not, it keeps out most of the dirt, mud, road kill, etc
As Ron said, you have to support the sheet in the middle to take out the bulge. You can use a floor jack and a piece of plywood to support the center while you attach the edges. Just be careful and remember you are only holding up the plastic sheet with the jack. If you apply too much pressure you could damage a tank or something else on the other side of the plastic.
1996 Suburban 4x4. 350, 4.10 3/4 ton
2005 Jayco Jay Flight 27BH
1986 Coleman Columbia Popup.
I like the plywood and floor jack idea. Unfortunately, I have no one to help with the reinstallation of the Coroplast, nice to know what it is really called. Regarding the orientation, I am sure of the orientation, as there are several cut-outs and the waste drain to line things up and yes, there was a belly in the Coroplast when I tried to install it. The Coroplast was anchored with screws and large washers and they will be going back on.
I am thinking of installing the front edge with loose bolts, then sliding a sheet of plywood under the Coroplast, then a pair of long beams I have under the plywood and using short 2x4’s under the beams to raise the beams and plywood to the undercarriage. I have several sheets of plywood so I could rise the Coroplash almost the entire length at one time.
Although the Coroplast was originally sealed with urethane foam around the various pipes that penetrate the plastic sheet, the rodents apparently found a small hole in the foam and enlarged it to get in. Fortunately, they did not get into the TT, only the undercarriage and roof area. We had a cover on the TT and we did not see any problems until we took the cover off. My patio awning looked like Swiss cheese, along with a few holes in the rubber roof which were easily repaired.
I plan on reapplying the black urethane foam around the pipes, then overlapping the entire perimeter and around all other penetrations with black Eternabond tape. I know that any water that gets into the undercarriage needs to get out, so I plan to install soffit vents at the low spots to allow air circulation, drain water and keep things out. Any thoughts?