Originally Posted by canyon Rafter
I will start out by saying that you probably know there is no fix it in a can that can repair rotting plywood. Your best bet is to find the rotting wood and replace what is no longer strong enough to hold your toilet in place before you fall
through the bottom of your trailer while sitting on the commode!
good luck and happy camping!
Good point lol. What I did, for better or for worse, was to rip out the floor where I could see it and found out quickly that it was supported by one aluminum or steel cross member and styrofoam. After doing a lot more reading I decided that replacing it with marine plywood was worth a shot. Just because I'm paranoid I coated it with some epoxy wood rot stuff, it takes forever to dry was was as hard as nails. Unfortunately I had to put it in in sections because of the awkward space and the fact that the toilet ring was ABS cemented to the drain going into the black water tank. I glued it down as best I could with styrofoam adhesive and some sheet metal screws through the cross member. Then because I'm still out of a job I used subfloor leveling compound to smooth out the inevitable bumps between the sheets and covered it with a dozen or so stick on vinyl tiles. They are holding for now but when I get a chance I'm going to stick those on with vinyl adhesive. The trailer got over 100 degrees and that seemed to almost nail them to the plywood. I screwed the toilet ring down to the plywood and it went back on easily. It is so much better now it's a huge difference but I don't think I can ever get it rock solid because there are now 3 different pieces of plywood under it, only 1 of which is screwed down.
I tracked down one leaky shower faucet connection and my guess is that it made the situation worse but wasn't the main cause, we rarely use the shower and the water lines are only pressurized maybe 3 weeks a year total. The problem didn't appear all of a sudden and I think last winter was the last straw, it must be leaking from somewhere else. We got one weekend in before the water pump self destructed so I have a guy coming over (eventually) to fix that and an electrical
issue (the pump somehow took out the entire left side of lights
and it never blew either fuse). I replaced the vents over the bathroom, sealed everything with self leveling caulk, sealed every seam whether it looked waterproof or not and replaced the strip seal stuff on all 4 corners. I got some rubber roof coating to put on when I get a break. It needed to be done sooner or later anyway.
So the problem is "solved" although I know it's just a bush fix. The trailer has a limited life span, I always knew it wouldn't last forever after I discovered the insane stuff the previous owner did to it and covered up so I didn't see it right away. So if it gets soft again or any one of a bunch of catastrophic breakdowns happens it's time to go shopping again. We have beat the hell out of it for years so I got my money's worth out of it (well not so much money as I have a few grand of repairs into it lol).