Old bathroom subfloor question

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Old 03-02-13, 02:12 PM
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Old bathroom subfloor question

Hello Folks

I'm in the middle of a bathroom remodel. My new cast iron tub (installed by a plumber) is not as wide as the original one, which was installed when the house was built in 1949. As a result, I have a gap next to the tub between it and the existing mud/mosaic floor. The gap is 5" wide and 60" long where the framing is exposed. So, I filled it with 3 layers of 1/2" Durock which brings it even with the existing floor. I screwed them down but they still don't seem rigid enough, as there is slight movement when I lean on it with my hands.

Two questions: 1) Should I remove the durock and tack down some wire mesh and pour some type of mortar to fill the gap level, and 2) If so, what type of mortar should I use that can be poured 1 1/2" thick and be compatible with the mortar I'm going to use for my new tile? (I'm not using the premix stuff.)

Thanks
 
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Old 03-02-13, 03:36 PM
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Durock is not structural. That gap needs to be filled with plywood or OSB subflooring material, then only 1/4" durock under the tile. Set the durock in a bed of thinset and screw it to the plywood.
 
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Old 03-02-13, 03:44 PM
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OK that's what I'll do. Thanks a million for you help.
 
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Old 03-02-13, 03:47 PM
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Unless the edge of the existing tile and the lip of the tub both split a floor joists, you will also have to add cross blocking to support Larry's (correct) recommendation of Plywood or OSB subflooring.

Without access from below, I think that a tear-out will need to take place to stiffen up the subfloor sufficiently for a successful tile install.
 
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Old 03-02-13, 04:18 PM
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The edge of the tile rests on cross blocks but the tub does not. I've removed the durock. This is what it looks like now.
 
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Old 03-02-13, 06:38 PM
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So the tub is not sitting on subflooring?? Difficult to tell. What is the centering of the floor joists? Are they 2x4? Is that a ceiling attached to the bottoms of the joists? Sorry for the questions, but you opened a new can of worms.
 
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Old 03-03-13, 12:14 PM
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Actually, the joists run in the same direction as the tub. The framing visible in the picture is running across the joists. They are spaced at 24" and the tub is resting directly on them. There is some kind of planking, possibly T&G, also running across the joists.
 
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Old 03-03-13, 02:28 PM
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Others may have differing opinions and I respect that, so hang in there for their comments. In my opinion, this set up will fail. The tub should have never been set on 24" spaced scabs as they are. It should be resting on a subflooring. Your plumber knows that, or at least he should have. This incorrect installation will cause failure, and will not allow you to install subflooring for the tile in a proper manner. Let's see what some of the others have to say.
 
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Old 03-03-13, 02:51 PM
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I cant see the pictures well enough to know whats actually there. Is there a basement? Take better well lit pics close up. And from the basement where the tub sits.

Post #7 is somewhat confusing....
 
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Old 03-03-13, 03:49 PM
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Mike: from what I see, the tub is sitting directly on sleepers set at 24" oc, which are perpendicular to joisting and possible plywood underlayment. I think this bathroom was raised 2 1/2", and the plumber didn't set the tub on any subflooring (if that is a problem).
 
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Old 03-03-13, 04:15 PM
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Were the sleepers there I wonder? He should have cut the sleepers IMO and put plywood down to raise the tub. ( If that was the intention )

New cast iron tubs have 4 feet now but i still use a runner along the studs. It would seem then the tub is resting on the sleepers from the apron.

I wonder if its even level????
 
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Old 03-03-13, 05:04 PM
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And I wonder about the sharp edge force being placed by the tub's edge on the sleepers.
 
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Old 03-03-13, 05:32 PM
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Hello Folks

I'll try to clear up some of the questions. This bathroom is on the 2nd floor and is located over the back of my attached garage. There are 2x8 joists under the tub, spaced 12" oc. The joists run in the same direction as the tub, so they're perpendicular to the sleepers you see in the pictures. There's a ledger attached to the studs on the back wall (the 60" wall) and that length of the tub rests on it. The original cast iron tub was set in exactly the same way this one is. The tub is level. I took some additional pictures that I hope will add a better perspective.

The first shows the view into the room from the hallway. The far wall is an exterior wall.
The next two came out dark but I hope you can see that along the edge if the existing tile there is additional framing running parallel to the tub and the tile. The third pic is a closeup of the framing and sleeper. About 4 inches under the tub (not visible in the pic) is additional framing that runs parallel to the tub.
The last two are just to give some perspective on how the tub is situated in the room.
 
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Old 03-03-13, 06:21 PM
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Could you tell me what brand tub that is? Looks like a Kohler. Im not fond of the intallation, even though the other tub was installed resting on the apron....


I need to think about this some, but I assume it does not matter. Im sure your not removing the tub.

I believe sister joists and a sub floor would answer your flex issues. It all was plain as day that this would happen and the installer should of offered options.

What to do now? IDK..... Larryr?
 
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Old 03-03-13, 06:34 PM
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The walls are set for tile, so as Mike said, the tub isn't moving. My answer before all this took place would have been to slip two pieces of 3/4" subflooring under the tub to give it universal support. You were building it up 1 1/2" anyway, so that would bring the tub to existing floor level. As you have it now, you will bury the tub by 1 1/2". Maybe Czizzi will check in on this again with more information.
 
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Old 03-03-13, 06:52 PM
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Yes, the tub is a Kohler but I'm not having any issues with flex. The tub doesn't move at all.
 
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Old 03-04-13, 06:25 AM
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Guess I should have checked in earlier.......

Several observations and some questions. First off, you said that you are installing this cast iron tub to replace a previous one. What was wrong with the previous one, cast iron tubs last forever and it would have been a lot easier to reglaze the tub instead of replace. So give us the back history on the old tub. My curiosity has been raised as I see a rather large shim under the service end of the tub on the first sleeper. Why the large settlement in that area? Does the floor sag or list to that direction? The tile appears to lay flush to the sleepers on the mud bed.

I see you have rolled on some sort of waterproofing membrane on the cbu. Did you also include a vapor barrier behind the cbu?

I think that to carry the load of the tub and transfer the majority of weight off the sleepers, I would do the following. On the plumbing end of the tub, I would open up the wall behind the tub and install a jack stud under a ledger that takes the load off the sleepers and transfers it directly to an actual floor joist (Unless of course there is already a ledger board that runs along both short walls). Blocking tied directly into the exterior wall framing and under the skirt will remove pressure from the tail end of the tub on the sleepers.

Cross blocking between the sleepers will be needed to serve as a base for the rebuild of the floor to accept plywood/OSB/cbu and provide enough rigidity to install tile without flex. I would try to insert a 4x4 slightly staggered between the sleepers so that you can get framing nails into the end grain of these cross blocks as opposed to simple toe nailing. This would also allow for any height adjustments needed given the sagging sleeper in relation to the rest of the floor. Should also give him a sturdy enough platform should he need to make adjustments to try to duplicate the height of the existing mud bed.

This is one time, I wish I was actually standing in the room scratching my head. Would love to test everything for movement and such before closing it all up.
 
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Old 03-04-13, 06:54 AM
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Here is what Kohler says.

( I would say its the plumbers fault unless you gave an OK to have the tub installed like that. Any experienced plumber would never install it like that.)

Floor support under the bath must provide for a minimum of
49 lbs/square foot (239 kg/square meter) loading.



Additionally it says this.

Important Information
The bath must only be supported by
the feet. Do not support the bath by
the rim.


Make sure the bath is level, plumb,
and resting on all four feet. Install
metal shims as needed.
 
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Old 03-04-13, 07:15 AM
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I assumed that the apron was carrying the weight of the tub as it does look like it is pretty tight on the 2nd two sleepers. And the shim says that the tub is not resting on the sleeper at the front end at all. Which brings up another question, Does the drain clear the sleeper or did he have to cut it out to make all connections?
 
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Old 03-04-13, 07:34 AM
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Important Information
The bath must only be supported by
the feet. Do not support the bath by
the rim.
Sort of says it all, IMO. If I had the job to do, the tub would be removed and replaced on two layers of Subflooring material. I can't, in good conscience advise otherwise.
 
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Old 03-04-13, 07:51 AM
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If I had the job to do, the tub would be removed and replaced on two layers of Subflooring material. I can't, in good conscience advise otherwise.
I'm with you on that Larry and agree.

If I was the homeowner and the plumber did not say anything about the floor to me before he installed it , I would ask him to remove the tub at his expense. They get the carpenter to fix the floor, then have the plumber come back and re install at his expense.

I'm sorry but the plumber has to eat this one. And should if he has any type of professionalism.

But we do not know what was communicated with the homeowner.


 
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Old 03-04-13, 03:54 PM
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After reviewing several Kohler tub rough-in dimensions, I am crossing my fingers and asking this question of the homeowner. The general location of the feet on all the drawings I reviewed is in close vicinity to where the #1 and #3 sleepers are positioned. So there is a chance that the tub is in fact supported on its legs as required. Mully, reach your hand under the tub, feel for the feet (knobs on the underbelly of the tub) and are they resting on the sleepers? If they are, we can continue with the tile end of the discussion.
 
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