Stevo Posted December 30, 2012 Share Posted December 30, 2012 I just bought a 1984 21' Sunrader and I can feel (and hear) under the carpet that the subfloor at about mid-point is rotted and will need replacing. I'll probably replace the entire subfloor since I'm going to gut the interior (excluding the bathroom). I assume the existing subfloor is particle board (heavy!) and was wondering for those that have replaced the subfloor what material they replaced it with? Maybe something lighter than particle/wafer board? Thanks Quote Link to comment Share on other sites More sharing options...
zero Posted December 30, 2012 Share Posted December 30, 2012 I just bought a 1984 21' Sunrader and I can feel (and hear) under the carpet that the subfloor at about mid-point is rotted and will need replacing. I'll probably replace the entire subfloor since I'm going to gut the interior (excluding the bathroom). I assume the existing subfloor is particle board (heavy!) and was wondering for those that have replaced the subfloor what material they replaced it with? Maybe something lighter than particle/wafer board? Thanks OEM Sunrader floor was a "sandwich" design. starting at the bottom on the aluminum skin is 1/8" plywood, then 3/4" foam-board, then 1/2" CDX plywood (5/8" for plywood in total). Where I live in New York state, just about any motorhome or camper I work on has rot all the way down. I use foundation-grade 3/4" plywood on the bottom which is sort of overkill. But it won't rot and I don't like doing repairs twice. "Foundation grade" plywood is pressure-treated for rot resistance and then kiln dried and uses water-proof glue. Lumberyards rarely stock it and it has to be special ordered. Not to be confused with the PT sort of 3/4" plywood that is normally stocked and not dry - and of less wood quality. Any motorhome/camper/RV I've worked on had unvented floors with aluminum skin on the bottom against the road and weather. Moisure can build up in there and there is no venting that I've seen. After X amount of years - rot is common. I've got the floors torn out of my 1978 Toyota Chinook right now. They were all 5/8" plywood against the aluminum skin and just about all the wood is gone. If you want to do your Sunrader as it was originally - and all the wood is rotten - then I suggest you find some 1/8" hard-wood based plywood like marine-grade Sapele for the 1st layer.. I suspect when the Sunader was built they were using Mahogany. Then the foam. The new stuff would be polyC board made for compression. Then a layer of exterior grade 1/2" plywood. If saving weight is your primary concern - I guess you'd better study some of the newer synthetic materials being used. Just keep in mind that an RV doesn't have floor joists spaced every 12" or 16" like a building has. So something with inherent strength is needed. Quote Link to comment Share on other sites More sharing options...
Stevo Posted December 30, 2012 Author Share Posted December 30, 2012 Thanks! 1) Were all the materials used to create that OEM "sandwich" laminated or glued to each other, or was each layer of material laid on top of the next? 2) Regarding the aluminum skin at the bottom of the subfloor sandwich... Is it the aluminum skin that is touching the trucks chassis or is the aluminum skin laying down on top of the bottom of the coach which is made of fiberglass just like the rest of the coach? (which would mean that fiberglass bottom of the coach is what is touching the trucks chassis) Thanks again. Quote Link to comment Share on other sites More sharing options...
linda s Posted December 30, 2012 Share Posted December 30, 2012 here's a brochure which shows the sandwich section for the floor and ceiling http://f1.grp.yahoofs.com/v1/YLngUD22jIJC5kzQkuxSlGqy2SkHz5qgykTKRQNOLcrHASo_1_5Pi8XSEh2njsbGci7hup6sh34ve_Hr2J9fwQfevGWx6So/Coach%20Manufacturer%27s%20Information/Owners%20Manuals%20and%20Brochures%2C%20Etc./Sunrader/Sunrader%20Brochures/SunraderClassics.pdf The is no fiberglass on the bottom. Stuctural integrity is cause the floor sections are actually glassed into the side. I reinforced my 3/8 inch rotted floor with resin and hardiner like they use on This Old House to save old wood. Lots of little holes, pour it in and smooth out. Then I used 1/4 luan over that. Almost perfectly solid but if I had to do it again I would go with 3/8. I think 3/4 is just too heavy and takes away too much headroom Linda S Quote Link to comment Share on other sites More sharing options...
zero Posted December 31, 2012 Share Posted December 31, 2012 here's a brochure which shows the sandwich section for the floor and ceiling http://f1.grp.yahoof...derClassics.pdf The is no fiberglass on the bottom. Stuctural integrity is cause the floor sections are actually glassed into the side. I reinforced my 3/8 inch rotted floor with resin and hardiner like they use on This Old House to save old wood. Lots of little holes, pour it in and smooth out. Then I used 1/4 luan over that. Almost perfectly solid but if I had to do it again I would go with 3/8. I think 3/4 is just too heavy and takes away too much headroom Linda S I suspect that when the Sunrader was built - the hard faced polyiso-board made to take pressure was not available yet. Thus the reason (I assume) that they used a sheet of 1/8" plywood on the bottom with common soft styrofoam board over it. The thin sheet of plywood provided a hard layer in case pebbles or whatever came off the road and hit the aluminum. All-in-all the original floor was 1 3/8" total thickness. It could be repaired with a sheet of 5/8"hard-faced polyiso board and 3/4" plywood and no head-room would be lost at all. Or 1" polyiso board and 5/8" plywood over it. When it comes to floors and strength, 5/8" is about the minimum. I haven't checked lately on what is the current trend with hard-faced polyisocyanurate board but things have changed a lot since I worked in construction. Also if someone is not concerned about insulation - just wood could be used. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted December 31, 2012 Share Posted December 31, 2012 Nida-Core's the hi-tech way to go. http://nida-core.com/english/ http://thesupercamper.blogspot.ca/2006/09/super-camper-inspiration-concept-and.html Quote Link to comment Share on other sites More sharing options...
zero Posted December 31, 2012 Share Posted December 31, 2012 So don't panic, keep a cool head, stay sensible in your analysis. You may not need to do radical surgery to fix the bad section of the flooring. That may be true for RVs in drier and/or warmer parts of the country. Rarely holds true where I live in the northeast. In every case of RVs I've worked on, when a little rot was found "on top" it was just the "tip of the iceberg." Moisture soaks into wood and often lies in places you cannot see. Rot spreads the same way. In my part of the world, RVs spend a lot more time parked then going down the road and suffer from snow and rain damage. I just got done putting a whole new bottom in a 2002 truck camper and that's only 10 years old. My 1978 Toyota Chinook had a soft-spot in the floor so I pulled it all up. Underneath where the 5/8" plywood touched the aluminum skin, it was rotted everywhere (in a hidden area). Had I just fixed the one soft spot that was evident, the rest would of had kept rotting and spreading. Quote Link to comment Share on other sites More sharing options...
linda s Posted December 31, 2012 Share Posted December 31, 2012 The Sunrader that I fixed the floor on was my 86 Nissan. Spent most of it's life in Fairbanks Alaska and then was abandoned in a field in upstate New York for 2 years. Power cord stuck out the side and funneled water into the floor the whole time. Is that cold and wet enough for you. Gutting and ripping the whole thing apart was not required. Linda S Quote Link to comment Share on other sites More sharing options...
zero Posted December 31, 2012 Share Posted December 31, 2012 The Sunrader that I fixed the floor on was my 86 Nissan. Spent most of it's life in Fairbanks Alaska and then was abandoned in a field in upstate New York for 2 years. Power cord stuck out the side and funneled water into the floor the whole time. Is that cold and wet enough for you. Gutting and ripping the whole thing apart was not required. Linda S I can't speak for something you've worked on. Just commenting on what I've worked on. Also, the Sunrader is somewhat of an exception since it is seamless on top (not counting possible leaks around vents, AC, etc.). I've been tearing apart RVs (and boats) for over 40 years. Not once have found one with a rot-spot on the floor that did not have a lot more rot hidden elsewhere. I suspect your's was the same and it went un-noticed - but obviously, there are exceptions to everything. Even when all is not rotten, it is often "on the way", watersoaked and heavy. Where I live, boats suffer the same fate as RVs. Being used in the water isn't the killer. It's sitting outside and being filled with snow that does many in. That's the case with the Lesharo RV I just got. All the water damage is from snow. It collects all winter and then in the spring, melts slowly and creeps into near everything. I just stripped a lot of parts out of a 1983 Sunrader that's spent a few years in a northern NY junkyard. The floor is rotten/watersoaked everywhere. I at first wanted to buy the whole RV and fix it up but then decided it was just too far gone for the price. The junkyard owner wanted $800 for it. The 1978 Toyota Chinook I'm working on came from Louisiana. No NY winters. The floor had a few soft spots. I tore it all out and it's all rotten underneath where it touchs the aluminum skin. Unlike the Sunrader - it was not multilayered. Just 5/8" CDX plywood. Quote Link to comment Share on other sites More sharing options...
RHS Posted January 1, 2013 Share Posted January 1, 2013 The sunrader floor can feel spongie even when not rotted. a stiffener can often be added on the underside of the coach & laminate flooring on top can help. P.S. it doesn't get wetter in very many places than it does where karin lives. Quote Link to comment Share on other sites More sharing options...
linda s Posted January 2, 2013 Share Posted January 2, 2013 Karen My power cord could not be pushed all the way back in to the hatch because the previous owner had made a huge box in the closet area where the drawers had been. Went all the way to the wall taking up the space the power cord normally went. I took that out, installed new drawer system and replaced the power cord hatch. New ones are available at rv stores and ebay. Closes nicely now and water tight. http://www.ebay.com/itm/RV-trailer-electric-POWER-CORD-CABLE-HATCH-camper-NEW-s-/350593569896?pt=Motors_RV_Trailer_Camper_Parts_Accessories&hash=item51a1015468&vxp=mtr Linda S Quote Link to comment Share on other sites More sharing options...
Redwing Posted March 31, 2020 Share Posted March 31, 2020 Thought I'd resurrect this old post as Im in need of doing the subfloor on my 'Rader Looking for the strongest possible solution since I'm having to do it anyways, might as well do it right. Would NidaCore be stronger than Ply? Has anybody ever used it before? Will i need to build out a framing system below for added support/stability? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
JaySam Posted April 1, 2020 Share Posted April 1, 2020 I started by building metal support wings welded to the frame underneath, then replaced the 3/4" foam with 3/4" PT ply and then built up from there. Here's a thread that has some pics of what I and Rick did with our rotten floors: http://toyotamotorhome.org/forums/index.php?/topic/11826-help-with-rotten-floor-sunrader/ And here's another thread about the rebuild process I'm going through with some others posted as well http://toyotamotorhome.org/forums/index.php?/topic/11856-sunrader-floor-repair-gut-and-rebuild/ Good luck with everything! Quote Link to comment Share on other sites More sharing options...
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