2fiftyr
Advanced Member
I posted a separate thread "395MS Fresh Water Leak - Wet Underbelly" to explain a water leak due to a manufacturer defect (1 3/8" tank hose connecting both tanks was punctured by a self-tapping screw after 3 years of use). Model 395MS 2021. In this thread I wanted to share some thoughts and tips that might help others when having to remove the coroplast underbelly on these large trailers and then re-install. I appreciate this forum and how much information and tips I have gathered as I do all my own RV repairs.
1) Before starting, I drove the trailer up on some wood planks (3" total thinkness) to gain additional space underneath to move freely on my creeper I bought at HF for $50 dollars. That worked so well on my concrete driveway. I moved about very easily.
2) I split the the underbelly midway between the two water tanks to create a more manageable way to remove and replace the coroplast. I added a piece of 3/4" steel tubing I had to an existing cross member to adequately connect the corroplast. I then bought some aluminum flooring thresholds at HD to secure the edges. I split the coroplast right behind the forward tank fresh water drop as I didn't need to go any further forward on the underbelly. The visible signs of water were all to the rear of that point.
3) While I had everything open, I took time to inspect all the wire, plumbing, and hydraulic routing. For the most part it was pretty good, but I did tie wrap and strain relief some areas.
4) The R7 insulation the factory installed was damaged and torn. I wore a mask and clothing of course and removed all of it. I replaced with new unfaced batts of R11 (3 1/2" x 15 1/4" x 93"). 16 batts per package and my cost $66. While it was just a little thicker, it compressed at the tanks just fine. The width and lengths worked perfectly between all the cross members. I also added a lot more insulation in areas I could to really improve the overall insulation in the floor. I bought a box of the 24" steel wire insulation retainers typically used in ceilings and floors to hold up insulation. They worked great to secure all the insulation up in the frame. This made it super easy. They could be looped together, cut, bent, stuck through the insulation, etc. in so many ways to neatly hold all the insulation in place. No more relying on the coroplast to hold it up. A tip I suggest is to place a box fan on side of were you are working (on the ground) so it creates air flow to move away any of the insulation fibers and dust from the underbelly as you work to tuck and secure each batt. It is summer so it also kept me cool.
5) I used a bunch of 5 gallon buckets and stiff foam blocks I had to elevate the entire coroplast sheet up against the bottom of the frame/insulation while I positioned it into place and secured it. That worked really well. Anything like cardboard boxes etc. would work.
I hope others can benefit from this information.
1) Before starting, I drove the trailer up on some wood planks (3" total thinkness) to gain additional space underneath to move freely on my creeper I bought at HF for $50 dollars. That worked so well on my concrete driveway. I moved about very easily.
2) I split the the underbelly midway between the two water tanks to create a more manageable way to remove and replace the coroplast. I added a piece of 3/4" steel tubing I had to an existing cross member to adequately connect the corroplast. I then bought some aluminum flooring thresholds at HD to secure the edges. I split the coroplast right behind the forward tank fresh water drop as I didn't need to go any further forward on the underbelly. The visible signs of water were all to the rear of that point.
3) While I had everything open, I took time to inspect all the wire, plumbing, and hydraulic routing. For the most part it was pretty good, but I did tie wrap and strain relief some areas.
4) The R7 insulation the factory installed was damaged and torn. I wore a mask and clothing of course and removed all of it. I replaced with new unfaced batts of R11 (3 1/2" x 15 1/4" x 93"). 16 batts per package and my cost $66. While it was just a little thicker, it compressed at the tanks just fine. The width and lengths worked perfectly between all the cross members. I also added a lot more insulation in areas I could to really improve the overall insulation in the floor. I bought a box of the 24" steel wire insulation retainers typically used in ceilings and floors to hold up insulation. They worked great to secure all the insulation up in the frame. This made it super easy. They could be looped together, cut, bent, stuck through the insulation, etc. in so many ways to neatly hold all the insulation in place. No more relying on the coroplast to hold it up. A tip I suggest is to place a box fan on side of were you are working (on the ground) so it creates air flow to move away any of the insulation fibers and dust from the underbelly as you work to tuck and secure each batt. It is summer so it also kept me cool.
5) I used a bunch of 5 gallon buckets and stiff foam blocks I had to elevate the entire coroplast sheet up against the bottom of the frame/insulation while I positioned it into place and secured it. That worked really well. Anything like cardboard boxes etc. would work.
I hope others can benefit from this information.
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