Intimidated by floor repair, looking for guidance

[daveemac]

1989 Odyssey Americana--rear door, rear bath.  Previous owner made a LOT of changes, including removing the toilet.  I felt a soft spot under the plank flooring and figured it was where the toilet hole is...I thought I'd have to patch the round holes, which only worried me a little.

Now I've got the planks off and find myself with a situation--basically the holes weren't weatherized properly and water got in there, so there's a good sized chunk of rot.  It's the center third of the rear third of the coach--in line with the trailer hitch, just inside the wall.  The wood at the peripheral edges of this section seems fine, but the back edge is gone I think.

I've watched a bunch of videos, but most of them are for campers with joists, or with metal reinforcement.  I haven't seen anything quite like my situation, so I'm really not sure what to do.  I dropped the black tank today which gave me a better look, but I'm still not sure how to do this.  (Fwiw, I made many searches of the archives here....but it seems like 75%+ of the entries are about Sunraders. I couldn't find much about my situation.)

I want to know:  how much wood I need to replace, what kind of wood & preparation, how to attach it, how to integrate the new piece with the waterproof barrier on the bottom, integration and weather sealing with the back edge, etc.  If there's a link that explains how, that would be great--I'm not expecting someone to type the whole thing out.  I saw a thread from 10 years back where a forum expert said there was an easy way to do it, but he didn't explain the method.

I'm also curious to know how much you think a shop might charge to fix it.  I'm in Sacramento, and if you have any suggestions they are most welcome.  Thanks!

[linda s]

Sunrader floors aren't fiberglass. They are wood same as yours. Look at Toyoguy, Bobthebuilder and some others work. You can find it a search or just search Sunrader floor. 

Yours looks pretty bad. Replace everything with any damage. Layers, sheet metal at bottom to protect from road, layer of plywood, insulation then top it off with top layer of wood. Fiberglass over all for durability. 

Linda S

[IdahoDoug]

A shop would charge you more than the coach is worth to repair that.  The instructions are great, and no technical skills are needed beyond the ability to cut shapes in wood that fit, and a willingness to learn the simple talent of laying fiberglas.  You can do this!

[daveemac]

Thank you Linda and Doug.  My floor doesn't seem to use the "sandwich" floor of Sunraders--no styrofoam, and no aluminum underbelly.  Seems to be 3/4" ply plus the strong plastic sheet that covers the entire underside of the RV.

I need to patch the holes, waterproof the patches, and fix the plastic sheet.

I'm not sure how to graft the new piece(s) in, or how to reseal the plastic sheet to prevent water entry.  I'm most concerned about how to get new plywood under the shell, but I'm hoping I can keep the piece that's under there now--reinforce it somehow and graft to it so I don't have to mess with shell stuff.

I'll cut away all the rot today and get a better idea of what's usable.  Is it easier to graft to straight edges, ie, should I cut away a rectangle? 

I'll keep reading the archives, any further links or suggestions are appreciated, thanks again.  
 

[linda s]

That plastic sheet you're talking according to Odyssey is ABS sheeting. One of the easiest things to bond to other sections of ABS. Search site for ABS slurry. I've posted it tons of times. Odyssey also claims the floor was insulated. Could it just have compressed so much you can't see it. 

Cut out more than you need. keeping it square or rectangle will make it easier. Fiberglass over whatever you do will certainly make it last longer and help tie it to walls. Tie it all together with a 1/2 inch sheet of plywood over all existing floor. I know it's a lot of work but all the more reason to make sure you only have to do it once. 

Linda S

[daveemac]

I think if I cut it right I can position a piece of plywood so that it's supported on all four sides, plus one crossmember support.  Three sides would rest on a metal beam (sharing with the old wood), and the back edge has its own support.  I'd staple the edges at the seams, seems it'd be super strong

My biggest concern is the back edge.  I'm worried about how I'll get the new plywood under the wall and on top of the rear beam--hopefully the wall won't drop too much when I pull out the old piece.

My biggest questions:  1) what thickness and grade of plywood should I use, and should I coat it with anything?  The wood I'm pulling up seems to be 5/8, or maybe a compressed 3/4

2) I'm hoping to keep the membrane in place as I do this.  How do I wrap the rearmost edge of membrane as it goes under the wall--does the membrane come under the rear edge and fold over the top at the edge?

Thanks as always!

 

[linda s]

Staples are not strong. Marine plywood and the thickness is determined by how many layers and current thickness of floor. I have mentioned fiberglass and fiberglass epoxy many times. That is the best thing to coat wood with but at minimum polyurethane. ABS does not come in sheets like a plastic bag. Even the thinest requires heat to bend. You do not want to use the thinest. Thicker means stronger. 

I have fixed a Sunrader floor but nowhere near this extent. I still screwed up. Top layer of plywood was too thin and floor flexes too much.

Hey guys someone else need to help on this. I'm at a loss.

Linda S

[daveemac]

Thanks as always Linda.  I've not been ignoring your fiberglass epoxy advice--I'm just not sure how to implement it. I know it will strengthen a piece of wood, but are you recommending it as a means for joining wood?  I have pretty much zero fiberglass experience...

The method I've described above seems like my best option, but I'd love some more input before I cut my floor back to share the support beams.  

And:  does anyone knows the proper way to deal with the ABS membrane as the wood passes under the wall?

 

[linda s]

When I say fiberglass epoxy think epoxy glue. When you really want something to hold your not going to buy Elmer's, your going to buy epoxy. Instead of a little tube now you've got a bucket of glue.  Add some mat which doesn't add a lot of thickness and now what you've put together has a shear strength of hundreds of pounds more than staples are going to give you. The wood itself is stronger too. Any other type of fasteners will pull out of the wood under the constant vibration and stress of a motorhome.  There are lots of floor repairs on this site. Please take some time to look at them

Linda S 

[ToyoGuy]

Hi daveemac,

This below, is just my observations, experience and opinion(s) on a big floor job that turned into an entire rehab due to "evolved moisture invasion".

I am one of the SunRader guys you mentioned, so I can't define a fix for you, but when I did my extensive floor repairs, there were few people who could tell me exactly "what to do" as well, and I had to figure most of it out anyway. I had to buy or find portions of materials and adhesives and experiment with Linda's and others suggestions on the bench, not on the rig. I also had a fairly evolved skillset including woodworking, fiberglass, welding and adhesives.

ie. Asking how to do some of this more complex stuff online can be like attempting brain-surgery on a walkie-talkie. I mean, how bad does plywood have to "look" to say "tear it out" ?

Key points IMHO:

You mention lots of re-fab on this rig, and that this particular work was done incorrectly.

I would be somewhat suspicious of other repairs and look more closely at the rest of the rig and think about what it's worth.

This is the time to re-inspect and re-evaluate your skill level, tolerance for learning how to safely work, willingness to spend money (it's always more than you think) , your time availability (mine took way longer than expected) and space to work safely and efficiently.

 I do not see this as a quickie, unless you want to adopt the PO's results.

You mention " I have pretty much zero fiberglass experience..."

I have seen mobile-RV repair guys on CL in your area, as there are a preponderance of RV's in Sac. and I don't think it will cost anything to hear what someone would charge and how they would deal with it. (Read "Aw yeah, here's how I did the last one of these" here)

Still want take the plunge? Look for someone (again, maybe Craig's List) who has some skills on RV's and fiberglass/epoxy resins.

Your previous posts are on an Oddessy 1 yr earlier, you may be able to learn some useful techniques from looking at that rig.

Not trying to dampen your enthusiasm, just wish I had done some of the above before I ended up waaay more invested in time and money than I thought I would be.

And lastly..................

" I saw a thread from 10 years back where a forum expert said there was an easy way to do it, but he didn't explain the method."

 Ummm, no comment.

BR,

TG