I posted this a couple of weeks ago in the Class A Motorhome section because it applies in general. But I will repost it here in case some interested Newmartian may have missed it. I'm catching up on a few posts that should have been made quite a while back, posts about some repairs and mods that I've done on my '02 Dutch Star. This is the first, and involves a major repair to the bathroom.
About a year after we bought the coach in mid-2012, I noticed that a hairline crack had appeared in a ceramic floor tile right in front of the toilet. About six months later another crack appeared. Soon I began to notice a bit of flexibility in the floor, the tile started to buckle, and from there the situation only worsened. Clearly there had been some leakage in the past and the floor was deteriorating, although we had observed no wetness or odor. I knew what I was facing, but still managed to procrastinate for another year or more, until finally some action was imperative. I documented the fix for any others who may have to do the same dance.
This is what the floor looked like at the start. A subfloor problem, as obvious as day. As part of the plan I also included a new toilet with a slightly higher seat than the old Thetford, and the flush pedal on the opposite side- the right-hand side as you face it. This would make everything easier for all concerned. So the Thetford was cut from the roster and a new Dometic 320 was ordered.
I disconnected the water, removed the toilet, and went to work with hammer, prybar, and scraper. The tiles removed easily enough, but not without some breakage. I managed to salvage about 6 of the dozen tiles removed. I had ordered a dozen new tiles from Newmar, but I wanted to have some spares, just in case. In the end I didn't need any. Below you see what I was then facing.
The plywood was pretty soft around the flange area, and that black mold looking stuff had spread quite a bit farther. It was quite easy to determine that I had to cut out the entire floor as far back as possible. Toward the two walls visible the old flooring was black on the surface but still solid. A couple of points: 1) the floor flange was in good shape and reusable. The flange itself was glued to a short downpipe. The other end of the downpipe socketed snugly (not glued) into an upright flange built into the top of the black tank directly below the toilet location. All these parts were in good shape and reusable. 2) You'll note in the picture the water supply line is formed of rigid PEX with a couple of pivoting elbows to make it "adjustable", and that there is no water shutoff. I modified this to a better solution. I cut the supply off close to the tee and installed a Sharkbite shutoff valve (directly accessable) and a braided flexible supply line. You'll see this in a later picture. I highly recommend the Sharkbite fittings for PEX. Easy slide-on install and absolutely no leaks.
Once I cut out the old floor, this is what I had.
Even the underlying framing members had some of that black staining. As part of the repair I treated all remaining black areas with some mold killing wood treatment recommended to me at a building supply. Can't recall the name, and there's no container left.
For a strong floor repair I knew I would need proper support around the entire perimeter. I just cut some scrap pieces of 1X pine, as seen in the picture below. Lots of screws visible along the edges of the old flooring to support the rim flanges.
The total floor thickness needed was about 7/8", and there was a tiny bit of wrack to it, so I used a piece of 5/8 for the base subfloor, well screwed to the rim flange all around. Then another layer of 1/4" underlay, screwed down every 6" both ways. Of course, the hole for the waste line was measured and cut into both pieces.
Naturally, repairs like this are never perfectly uniform and flat, so some floor filler was needed to yield a surface the tile would seat on properly. Fortunately, it's a small area. A small second application was needed to finesse a couple of spots See below.
Once the leveller cured it was simply a matter of laying down the tile. Layout was predetermined by the existing floor, and I only required 12 tiles. You'll note that I did not include the single gray diamond tile that would have been visible in the new floor. Newmar had no more of the notched tiles available.
BTW, many have complained of the high prices Newmar charges for parts, but I have not found this to be the case. Perhaps it is because I am buying miscellaneous parts for a sixteen year old coach, stuff for which there is little demand. These floor tiles, for example, only cost a few dollars each, with free shipping, along with some rubber cargo door seal and a few ceiling AC registers. All very reasonably priced.
Anyway, the two tiles that needed trimming for the waste hole were not cemented in the picture above. I measured and marked, then took them out and cut the respective parts.
To make circular cuts in ceramic tile, the best course (imho) is to use a diamond blade either in a saber saw (onsite) or a jigsaw (in your shop). See above.
The size and location of the final hole cut in the tile is important. Of course you want the flange directly above the black tank opening. You can flex it about a 1/4" in any direction, I suppose, but if there is any substantial slant in the pipe you may, over time, accumulate solid material on the sidewall of the down pipe. Not good.
But there's another factor. To properly install the toilet, the installed toilet flange should be resting on the finished floor surface. That is, sitting on the tile. This allows you to securely fasten the toilet down with the two flange bolts, and also get full even compression of the toilet sealing ring. But you also have to set a number of screws through the flange and into the subfloor material to securely hold the flange in place. So, the circular cutout in the tile must be large enough to allow the screw holes to reach the wood subfloor, but still small enough that the outer edge (1/4" or so) of the flange is fully supported all around by the tile itself. Take a look at Picture #11 & 12, below. In picture 12 I have placed the flange piece upside down so you can see that the screw holes are JUST inside the tile cut line, but there's still a fair bit of the flange ring remaining to rest on the tile.
With the tiles properly cut out, they were set in position and the downpipe and flange assembly installed and secured to the subfloor. See Pic #13. After all the tile has set up, apply the grout per instructions (how-to video is all over you-tube) and let that set up for a few days. In pic 14 below you can see the grout applied, and in #15 you can also see the shutoff valve and flexible water supply line I mentioned earlier.
With all the details addressed, it's time for the final step-- install the toilet. Set the flange bolts (T-bolts) into the appropriate position for your particular toilet, then set the flange seal in position on the flange. I use a few dabs of silicone grease to hold the seal in position while the toilet is being lowered onto it. It's easier with two persons, but doable by one. The toilet is not particularly heavy, but it is a bit ackward to handle. With two, one can lower the unit while the other lies on the floor guiding the holes in the toilet base down over the two flange bolts. Once the toilet is seated properly but before tightening, rotate it back and forth just a bit to be sure the seal is seated. Be sure the toilet is aligned, and snug down the nuts onto the bolts. The toilet should be good and snug, but not super tight. You should not be able to rotate the unit easily.
Once set in position and tightened, you're good to go. I hope this has been helpful. Good Luck!