Floor fix question

[russellseaton1]

Carpentry question. Not a woodworking question. House bathroom I am remodeling. Stripped the floor down to the plywood subfloor. 3/4" plywood. Around the toilet it is sort of, kind of, but not really rotted out a little. 6 inches all around the toilet. Water damage. Top 1/4" or less is flaking and soft and you can pull up the strands, fibers. But underneath, from the basement, it looks like good plywood. No rot underneath. So its surface damage only. I have access from underneath in the basement. Toilet plumbing is right in the middle of the joists.

I do not want to cut out the subfloor between the joists. Put in blocking on the joists. Put a new piece of plywood on top. Partly because the new plywood would be split around the toilet flange. And there would be seams along the edges of the new plywood put in. New flooring to go in will be vinyl sheet.

My plan is to glue and screw a sheet of 3/4" plywood underneath in the basement. Reinforce the damaged area from below. But I also think I need to do something on top too. Epoxy layer over the damaged plywood? Make the top smooth and solid for the new vinyl flooring to go on. With drywall when a wall is torn up and scarred, I just skim coat it with drywall mud and its as good as new. Would that work for a subfloor with epoxy skim coat? And which epoxy to use? Any other ideas?

[Markem618]

"Carpentry question. Not a woodworking question. House bathroom I am remodeling. Stripped the floor down to the plywood sub floor. 3/4" plywood. Around the toilet it is sort of, kind of, but not really rotted out a little. 6 inches all around the toilet. Water damage. Top 1/4" or less is flaking and soft and you can pull up the strands, fibers. But underneath, from the basement, it looks like good plywood. No rot underneath. So its surface damage only. I have access from underneath in the basement. Toilet plumbing is right in the middle of the joists.

I do not want to cut out the sub floor between the joists. Put in blocking on the joists. Put a new piece of plywood on top. Partly because the new plywood would be split around the toilet flange. And there would be seams along the edges of the new plywood put in. New flooring to go in will be vinyl sheet.

My plan is to glue and screw a sheet of 3/4" plywood underneath in the basement. Reinforce the damaged area from below. But I also think I need to do something on top too. Epoxy layer over the damaged plywood? Make the top smooth and solid for the new vinyl flooring to go on. With drywall when a wall is torn up and scarred, I just skim coat it with drywall mud and its as good as new. Would that work for a subfloor with epoxy skim coat? And which epoxy to use? Any other ideas?"

How well is the flange attached, if it needs reinforcing you could do it with the blocking underneath. If the flange rocks it will be a problem later on, wax rings do seal but rocking causes problems with sealing, which can lead to sewer gas causing a stink.

Leveling compound would work it will flow out flat just seal around the pipe.

[krw]

I'd just rip the subfloor up, block it, and replace the subfloor between the two joists. It's not all that difficult. I'd not split a sheet under the toilet.

That certainly wouldn't be my plan.

[Michael]

Maybe I'm not understanding what you're saying, but it would seem to be a lot easier just to cut out a square and replace the subfloor. You can reinforce the seams with blocking.

[Leon]

I would replace the trotted wood. Who knows if it will continue to deteriorate. Then use that sealer stuff on the new floor. IT MIGHT be the RED stuff you paint on behind shower tile.

[Leon]

would replace the trotted wood. Who knows if it will continue to deteriorate. Then use that sealer stuff on the new floor. IT MIGHT be the RED stuff you paint on behind shower tile.

[DerbyDad03]

Maybe a picture would help.

Why would the plywood need to be split? Can't you cut the existing plywood back to mid-joist on both slides of the flange and then cut a hole in the patch for the flange? Use blocking for any seams that are perpendicular to the joists/unsupported.

The main question is "Why a split in the patch and not a hole?"

[Scott Lurndal]

To use your solution (which I agree is better), Russell would need to remove the flange. If ABS, that means cutting the waste pipe below the flange far enough to support adding a coupling, a shorter length of pipe and a new flange. If CI, it may be easier if you can melt the lead/oakum and remove the old flange temporarily.

[russellseaton1]

I was planning on the split to go around the drain pipe. Figured the plywood would provide better strength running length wise. 2-3 foot long by about 7 inches wide. Work both halves around the drain pipe from the sides. As opposed to your suggestion of putting full width, 15 inches wide, in front and behind the drain pipe. But once glued and screwed in place underneath, probably no difference in support. There has to be some cut in the patch piece underneath. At the circle for the drain pipe. Either across the joist bay or along the joist bay.

I need to go look at the job again. Get a better understanding of how water damaged the subfloor is. And whether the existing drain pipe flange can be secured in place. Or is the water damage already ruined the area around the flange. And evaluate how much access I have underneath and what gymnastics will be required to get wood up under the floor. It may be easiest after all to just cut everything out from up above. Put some support blocks along the joists under the floor. Should be easy to glue and screw those on. Then just lay the patch piece in from the top.

I'll keep you informed of the progress once I figure out more. Based upon the comments from you guys about things I had not thought about.

[russellseaton1]

Its plastic waste pipe. I think. I don't really want to cut it. Its obviously not wide open and easy to get to. Its short and 90 degree elbows under the floor in the joist bay. Memory is bad at the moment. I think its plastic. Or maybe 6 inch copper. It is definitely not cast iron. No cast iron waste pipe.

The split instead of hole was to get the patch piece around the waste pipe from the sides, or front and back. I was always going to drill a hole for the drain pipe flange. But getting the patch around the pipe and flange required a cut of the hole. Either cut the hole length wise parallel to the joists, or side to side across perpendicular to the joists. Working under the assumption I was not going to take the drain pipe and flange out. Work the patch around the pipe while it was in place from underneath the floor.

[russellseaton1]

Right now I need to look at the project a lot more and maybe even take notes. And use the information provided here to evaluate things better. My first idea was maybe a spur of the moment off the top of my head idea. Maybe not the right one after all. Maybe, probably, doing it right by replacing the damaged wood might be the best way to do the job. Maybe. Thanks for the idea of the tile sealer. I'll look it up.

[DerbyDad03]

I don't necessarily agree. Both Danco and Pasco sell toilet flange repair rings with screw tabs that allow you screw the ring to the subfloor outside of the perimeter of the flange itself.

This is the Danco version and my Amazon page showed the Pasco 21013 at the top as an option.

Granted the tabs don't extend very far out onto the subfloor, so it would require a fairly precise hole, although I can think of a couple of ways to make sure that the screws bite into a sufficient amount of wood to be secure.

The fact the OP can access the plywood from below makes that even easier.

Again, not knowing the exact situation/layout makes it hard to give a definitive "Yes, they will work" proclamation, but it might be something worth looking at.

[DerbyDad03]

Not necessarily. Look at my response to Scott about using the Danco or Pasco flange repair rings, which come with screw tabs.

Although, as you said, you have access from underneath, so a seam supported from below, should be fine. In fact, even if you couldn't get underneath, a piece of wood bridging the seam could be done from above. Just screw it to the bottom of one side of the patch. leaving enough overhang to screw the other side of the patch to the brace once it's in place.

Bottom line, I'd still remove the rotten wood. Just be sure that whatever wood you plan to use ends up flush with the existing floor - before you get too far into the project. 3/4" plywood isn't always 3/4", if you know what I mean.

[russellseaton1]

Thanks for the links to flange repair rings. Not sure I need them or not. Right now I am going on memory. And as I have realized over the past number of years, my memory seems to not remember a lot of things. So I have to get back to the house and look at things a lot closer and think about what I should do. Also reassess how water damaged the floor is. And how much floor would need to be replaced. And is the flange attached to anything right now or is it floating in space? And which direction is the waste pipe coming from? Can I get lots of access to it to change it if need be? Things like that. Based on comments here, my initial idea of just putting a piece of plywood on the underside and trying to put a skim coat of epoxy on top to take care of the damaged subfloor may not be correct.

[DerbyDad03]

Please be aware that the only reason I mentioned the repair ring is because the ones I showed have tabs for screws that are outside the perimeter of the flange itself.

I'm *not* saying that your flange may need to be repaired. I'm suggesting a possible solution to your "seam concern". The screw tabs on the repair ring may allow you to use the "single piece of plywood with a hole" method.

With the repair ring the subfloor doesn't need to go under the flange since the repair ring can reach out onto the patch.

Good luck Keep us updated.

[russellseaton1]

I was able to get back over to the house and reassess things. Apparently having the subfloor exposed to the air resulted in a lot more damage over the past week. Amazing. I am positive the subfloor was not that damaged last time I looked at it. It will have to be replaced.

I began the process. By drilling a couple holes in the floor near the drywall to mark out the back end of the patch. Looks like all the wood behind the toilet pipe in the joist bay will have to come out. Back to the drywall. And about 1 inch in front of the toilet pipe. That is the wood part. Easy enough to figure out. And I have to cut the new plywood subfloor around the toilet pipe and the water pipe sticking up through the floor. But that is just cutting and gluing and screwing pieces in place.

Now the odd part. The toilet drain. Sticks up through the floor about 1/4" or so. But it has no flange on it. Where you put the T bolts that move back and forth and go up into the porcelain toilet. Its just a 4 inch pipe, plastic, with a rubber cone on top. About 1 inch or so thick rubber cone on top of the pipe. Tapered rubber cone. Obviously that is where the toilet sits down onto and the wax ring. But the flange for the T bolts is completely separate. I did not tear the toilet out so cannot remember if there was a separate ring that was also torn up. Assume so but I will have to ask. Buying a separate metal flange ring is no big deal. Easy to screw it down.

But I am wondering about the support for the waste pipe in the basement. It has some metal straps underneath it to keep it in place. But its not really super solid. You can bang on the waste pipe and move it a little bit. I have never dealt with toilet drains that did not have the flange built into the pipe itself. Glued on fitting that has the screw holding slots. Fitting is glued onto the waste pipe. Then you screw the fitting into the subfloor. I can and likely will have to buy some more support straps and secure the waste pipe even more. And maybe add some wood blocking to really secure the waste pipe in place so it cannot possibly move.

I'm sure it works. Having the flange that capture the T bolts completely separate from the waste pipe itself. But its different than what I am experienced with.

[Markem618]

The old flange probably has been removed, maybe it is still on the old toilet because it would not unbolt? The tapered cone sounds like a seal for a non glued flange screwed to the disintegrated plywood.

Make sure the waste pipe is half a bubble off and secure it so it won't move would be my fix to make just a bit better.

Four inch PVC would fit through a four and a half hole, so if you have a hole saw that size would save a seam around the pipe.

[russellseaton1]

Just talked to my brother and the old metal flange was tossed out into the yard by my mother. I'll look at it for fun when I get back there. Yes the rubber tapered cone is designed to fit into the hole on the bottom of the toilet. With wax ring to seal it completely. I will buy a new metal flange to go around the tapered rubber cone. After putting in new subfloor so there is something solid to screw to.

But I was just unaware of this method of installing a toilet. Flange not attached to the drain pipe? So the toilet is not bolted solidly to the drain pipe? Seems weird to me. All the toilets I have installed in the past had the flange, where the T bolts go, attached to the drain pipe. So there was a mechanical connection between the toilet and the drain pipe. With the wax to seal it up for gases. But it was all mechanically connected. But with this method, there is no mechanical attachment between the toilet and the pipe. Seems odd to me.

Assume by "half a bubble off" you mean the bubble in the level is pointing so the drain pipe is sloping downwards in the right direction. I will definitely check the slope and make sure the drain pipe is secured from every angle.

4 and 1/8" hole saw. Just installed some round electrical boxes in the garage ceiling and that size was perfect. May have to use a jigsaw to make the hole a little bigger to fit over the drain pipe cone thing sticking up through the floor a little bit. Or just buy the right size hole saw. That's probably the better idea.

[Markem618]

I have seen it done on TV, but have never run into one in life. Correct on the level, carpenters centered, plumbers a half off.

[DerbyDad03]

Have you measure the rough-in of the waste pipe? Any chance it was this type of toilet?

Have you removed the rubber cone? Maybe the old plastic flange was broken and removed. Then the cone was stuck in the pipe and a repair ring was screwed to the floor as a separate piece.

Any chance you could post a picture of what you currently have?