big trouble in little bathroom

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Old 10-05-08, 04:55 PM
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big trouble in little bathroom

I am trying to level /flatten my bathroom floor in order to lay some c/tile. I have mosaic tile in there now that is about 40 years old that is laid on top of about an inch and a half of mortar. I spread self leveling thinset down but it did not work. I think I made problem worse. That stuff is hard to work with, it starts to harden too quickly for me to spread it out and give it a chance to work. I don't want to rip up the existing tile down to the sheathing b/cause I'm not sure about asbestos. I can't lay Hardibacker b'cause that would raise the floor above the toilet flange. If I can tell if the old tile does not have asbestos in it I would rip up the floor then lay Hardibacker down then lay the tile. Any suggestions out there?
 
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Old 10-05-08, 05:11 PM
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Rip it all out. Installing Custome LevelQuick RS is a tough task if you are by yourself. You typically want a helper to mix it, and you set it.

If you are worried about asbestos, wear a dust mask and mist the area with water, you will be fine.

The toilet flange issue should not be whats holding you back. You can easily install a flange extender and/or a thick wax ring.

What are the joists like? Size, spacing & unsupported span.
 
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Old 10-06-08, 09:21 AM
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Are you thinking that the existing mosaic ceramic tile and mud contain asbestos????? I dont think so.
 
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Old 10-06-08, 10:36 PM
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Rip it out. OKC is right. You main concern should be how much weight is on those joists.
 
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Old 10-11-08, 05:48 PM
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Ok I tore out the old tile and mortar down to the metal lath. My ? is should I keep the old lath or should I replace it with new lath. The existing is in descent shape, but very old. If I do replace it should I put down tar paper for a moisture barrier? This was my plan:
1. new paper
2.new lath
3. thinset
4.hardibacker
5.new tile
6.cold beer
Is this a good plan or should I eliminate steps 1 and 2? Thanks for the help guys. P.S. I hope there isn't asbestos in that old mortar and tile. I'm still a little worried about that, I misted the area but there was still alot of dust. I guess I shouldn't worry b'cause it is already done.
 
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Old 10-11-08, 08:29 PM
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No asbestos in mortars..no need to worry. Asbestos was found in the older vinyl type tile and adhesives.

What is the subfloor, concrete or wooden? Doing a good mud screed is typically not for the DIYer, so you may want to get some help with that. A mud floor is not laid with thinset. It's normally made from sand, portland cement, among other things. I've never screeded a entire floor, only a shower, so I may not be the best person to tell you what goes on.
 
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Old 10-12-08, 02:13 AM
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Around here you will be hard pressed to find anyone that knows how to do a "Mud Bed" installation of tile. Old timers never taught the new guys, and with backer boards and membranes these days, Mud beds are a lost art.
 
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Old 10-12-08, 08:15 AM
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I am a little confused right now. I am not looking to create a mortar bed I am looking to lay thinset under the hardibacker so it adheres to the floor and hardibacker. The subfloor is plywood that the hardibacker is going to go over. There is a metal mesh that was laid down from the previous tile job years ago. I am just trying to get the floor flat in order to lay the new tiles. Do I need that metal mesh there to stabilize the mortar and hardibacker or can I just add the mortar to the floor and then lay and screw the hardibacker to the subfloor. If I can't use thinset under the backerboard what type of mortar do I use? I know there are alot of ? but I want to do this right the first time, I don't want to fix this thing a few years from now. Thanks again for the help
 
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Old 10-12-08, 10:50 AM
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I understand a little more now.

Usually lath was used in a mud bed, not just thinsetting tile down.

If your floor is not FLAT, then you should correct your subfloor defects prior to laying down your hardiebacker, like removing the wooden subfloor and replacing with new.

What is the thickness of this wooden subfloor? Can you tell us the size of your floor joists (2x?) and the spacing and unsupported span? We just want to make sure your floor is good enough for a new installation.

You just need to lay your cement board in a bed of thinset and screwed down, then thinset and tile, remembering to tape the seams as you tile. No need for barrier or lath.
 
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Old 10-13-08, 08:04 AM
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Originally Posted by rmarray View Post
I am a little confused right now. I am not looking to create a mortar bed I am looking to lay thinset under the hardibacker so it adheres to the floor and hardibacker. The subfloor is plywood that the hardibacker is going to go over. There is a metal mesh that was laid down from the previous tile job years ago. I am just trying to get the floor flat in order to lay the new tiles. Do I need that metal mesh there to stabilize the mortar and hardibacker or can I just add the mortar to the floor and then lay and screw the hardibacker to the subfloor. If I can't use thinset under the backerboard what type of mortar do I use? I know there are alot of ? but I want to do this right the first time, I don't want to fix this thing a few years from now. Thanks again for the help



I was making a point, that from what you described during removal, it sounds like a good mudbed installation from years long ago.

The subfloor needs to meet strict defection ratings. TCA recommends at least 1-1/8 of wood subfloor, before any cement tile backer board(CBU) is installed. CBU adds no stregth to the subfloor. It is just there to isolate movement(shrink & swell) in the wood substrate.

The mortar under the backer board is not there to get it to stick. Far from it. It is just there to fill any small voids under the CBU. You nail or screw the CBU, the mortar also helps you keep the panels even.

You don't use metal lath under CBU.
 
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Old 10-13-08, 12:08 PM
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Around here you will be hard pressed to find anyone that knows how to do a "Mud Bed" installation of tile. Old timers never taught the new guys, and with backer boards and membranes these days, Mud beds are a lost art.
Definitly not a lost art. I use mud beds every chance I can and know others that do as well. Its least costly and by far the best. No better way to get a nice flat floor. Better than cement board, membranes and anything else you can think of.

The subfloor needs to meet strict defection ratings. TCA recommends at least 1-1/8 of wood subfloor, before any cement tile backer board(CBU) is installed
Not the case. Read instructions from the cement board manufacturers. Most can be used over 5/8" or 3/4" t&g plywood or OSB on 16" centers. TCNA does require 1 1/4" of plywood if you are setting direct to the plywood (no cbu or membrane used).
 
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Old 10-13-08, 05:28 PM
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I'm not sure what the floor joist are underneath. This b/r is on the second floor so I'm assuming the sub-floor is at least 3/4" plywood and the joists are 2x8 @16" o.c. There was alot of old mortar on the floor before ( about an inch of mortar plus the mosaic) so I'm thinking that the Hardibacker and new tile are going to be alot less heavy then the old stuff. The total floor area is not that big about 44 sq ft. not including tub and vanity area so the lbs per sq ft should be strong enough to hold the backer and tile. What do you guys think? Thanks again for the help.
 
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