Waterproofing & Sealing the Bottom - Fiberglass RV

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Old 05-03-2006, 04:33 AM   #1
Lindy Auble
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Greetings. We just purchased a very nice, newly refurbished 1978 13' Scamp. We love it & hope to have around for a long time. It needs very little in the way of updates, etc; but we are concerned about waterproofing/sealing the underside. Years ago we bought an older Omega trailer with rotted out floor boards -- and quickly learned about problems with mice, etc. It was so bad we finally gave up on it & got rid of it. So we're looking for any suggestions on what might be the best (and most cost efficient) way to seal & waterproof the underside of our new egg? Is there a product available that might act as a resin-based coating, that we could just paint/roll-on, ourselves?
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Old 05-03-2006, 08:23 AM   #2
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Trailer: 84 16 ft Scamp
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I'm not sure you need to do that.

There's two schools of thought on this issue
1) Seal the water out (easier said than done).
2) Leave floor panels exposed underneath and let any moisture evaporate.

Some manufacturers have chosen the first. Burro comes to mind. Others such as Scamp are in the second group. I have a Scamp and would consider it almost impossible to seal the floor effectively.

A better approach, I would think, would be to possibly paint on some anti-rot or anti-fungual stuff on the bottom of the floor boards. Before I did it, though, I would be very concerned with the smell and health effects of the product.

Replacing a piece of floor isn't such a big deal. In twenty years in western Washington, the only rotted piece was right next to the door. A dust mask and a four or five inch angle grinder makes for quick extraction. Screw and glue a doubler flange underneath, cut your patch to size and screw it down. That's the basic process.
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Old 05-03-2006, 10:38 AM   #3
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Actually the Burro floor is coated with fiberglass resin top and bottom. So it's sealed.
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Old 05-03-2006, 01:48 PM   #4
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True of my Burro too, but I go on the assumption that any time anything penetrates the fiberglass (screws into it from the inner shell) and into the wood there is a potential for rot if given enough water seepage.

I don't think we can necessarily rely on the fiberglass seal to either be perfect from the factory or remain that way through years of use. Trust, but verify.
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Old 05-03-2006, 05:59 PM   #5
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New Mexico
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And though Burro floors were indeed coated with fiberglass that sure won't stop rot forever, relentless assaults by water permitting. Note tip of iceberg below. Regardless, IMHO, it makes practical sense to coat raw, replacement plywood flooring with fiberglass resin, no matter how painful the job.
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Old 05-03-2006, 10:00 PM   #6
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Many of the owners of older trailer on this site have totally solid floors that are bare plywood underneath the trailer. IMHO the failure of a floor is always due to water from above and not under the trailer. If all leaks from windows, doors, roof mounted vents or air conditioners, refrigerators, and plumbing are fixed, the floor will be good. And if water is getting into the trailer from any of these sources, having a floor that is "sealed" both top and bottom may just trap the water in areas where it cannot evaporate easily.

Tom Trostel
1980 Bigfoot 17' & former owner of 1973 Compact Jr
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Old 05-03-2006, 10:46 PM   #7
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Tom, that is my feeling also. I ended up removing all the vinyl from our Scamp, cleaned all the glue with a heat gun and scraper and sanded the floor smooth.

Then I coated it with several coats of grey latex floor paint.

I know it won't win any beauty contests, but I want it to be able to breathe. I might be carrying this a bit too far, but it just seems like the best thing for me to do.
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Old 05-04-2006, 05:12 AM   #8
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Trailer: Escape
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Now that I think about it, my trailer did have a heavy rug on its floor, a 14 inch square ceiling vent opening that was covered by a duct taped-on cheap aluminum turkey dish, water stained window curtains, and a sizeable gap at the door bottom. Plus, rusted old refrigerator vents, and the thing lay unused under a tree for 13 years.

Hmmm. See your point, guys. Yes, that could be major to my rotted floor.
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Old 05-05-2006, 08:54 AM   #9
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When I rebuilt my first trailer, the water for the floor damage did indeed come from inside. I believe it was seriously enhanced because the trailer had carpet. The carpet stayed wet for long periods, right next to a bare plywood floor. Another spot was a leaky toilet flange, just as in many houses.

What I did was:

1. install the plywood
2. force chopped fiberglass mat and resin into the floor cracks with a stiff putty knife
3. cover the floor top with fiberglass resin
4. lay a light fiberglass matt on/in it
5. When it dried, cover with a second coat of resin
6. when it dried, instal high quality linoleum
7. lie on my back under the trailer, and paint the floor bottom with varathane gloss almond paint.(2-3coats)

I never had another problem. A key point with the fiberglass is that i have had experiences where adding too much hardener overheated the resin, creating cracks/bubbles, and a much weaker seal. In this case, i intentionally went with an underdose of hardener.

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Old 05-05-2006, 04:39 PM   #10
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Trailer: 84 16 ft Scamp
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Sounds like you will get another 25 years or more out of your Fiberstream without needing structural repairs to your floor.
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Old 05-05-2006, 06:53 PM   #11
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Trailer: 1992 13 ft Scamp
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Greetings Lindy, from the west end of Big Sea Shining Water,

We purchased a '92 Scamp 13ft. almost a year ago and had to do a lot of floor repair/replacement. It is cronicled in an album in Yahoo Scampers Group photos section under "Dave and Diane's Project Scamp".

The rot issues we encountered were almost all from the inside out caused by leaks not recognized and/or ignored. The underside of our scamp floor wood is coated with the fiberglass resin. The interior side is not really treated with waterproofing. In the work we did, all replacement wood was coated on all sides and edges with two coats of polyester resin (Fiberglass, resin only) before instalation. The areas under the kitchenette and front bench were sanded and double coated as well. The main floor area in front of the kitchenette was not coated since it was not possible to seal the edges without pulling the floor in that area. We didn't want to have the top and bottom sealed, only to have water soak into the edges and have no escape.......our logic anyway.

On the underside of the floor, in areas not replaced with new, we recoated the existing wood as best we could with fiberglass resin. We did this by jacking the trailer up, supporting it securely, and sliding under on a large sheet of cardboard. Of course, wear old clothes, goggles and rubber or vinyl gloves. My wife set up several 2-3 ounce paper cups of resin. I cut several squares of heavy plastic sheeting (construction house wrap weight) to a convienent size. For me that meant at least 1 sq ft or larger. I slid under the trailer, got comfy, planned my attack strategy, and then asked for my wife to mix the first cup of resin. With me holding the plastic sheet sort of bowl like, she poured about half (more or less) of the resin onto the plastic. I plastered it to the underside of the trailer and smeared it around into all the nooks and crannies I could. The plastic sheet kept the resin from dripping back on me and alowed for it to be easily spread with much less mess than I was prepared to endure. My wife mixed the resin and kept it comming at about the speed I could spread it. Once a sheet of plastic got too gummy, I'd discard it and grab a fresh sheet and keep going. The job went pretty fast and two coats were applied in about an hour.

Well, that's what we did and how we did it. We'll find out if it was the right thing to do if the floor is still sound when the kids inherit the Scamp in about 30 years (dosen't hurt to be optimistic)

Dave and Diane
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