Re-use old mud bed?

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Old 12-29-19, 05:42 AM
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Re-use old mud bed?

An older small bathroom (32sq.ft.) with a movie style floor that I want to replace with 12x12 ceramic or porcelain. I tested a spot and was able to knock the old tiles 1"x2" off the mud bed leaving a fairly smooth surface. Do I need to remove the mud bed and start from scratch or can i re-use the mud bed and just put down a thin mud layer to set the new tile? Current mud bed looks to be about an inch thick where I checked it.

-Peter
 

Last edited by pjaffe; 12-29-19 at 05:43 AM. Reason: Typo
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Old 12-29-19, 06:11 AM
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I just remodeled a old bathroom with a mud bed like yours. Some of the tiles came off pretty easy but most we had to break up the mud bed. I would guess you will the same thing. we took it all.out
 
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Old 12-29-19, 06:21 AM
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Sounds like having poorly adhered tiles will be a plus for you.
If the bed is smooth and not cracked then I would reuse it but you will not know that until all the tiles are removed.
 
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Old 12-29-19, 07:35 PM
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Mud bed was not in good shape

As suggested, after removing about 1/3 of the tile I did see that the mud bed was not as pristine as I hoped. I switched to taking up the entire mud bed with the tile. Now, after about 2/3 of the floor removed I am glad I did.

For the next step of planning the new flooring, I am experiencing to use a 12"x12" although I didn't pick it yet. The mud bed with tile was about 1.125". As best as I can tell so far, there is no real subfloor other than planks. I was thinking to put down a 3/4" plywood with a 1/4" cement board. That would give me room for a 1/4" tile. Am I on the right track? The space is small with about a 36" wide floor in a U shaped layout. Total of about 32 sq. Ft.. I have no info on floor joists or type of wood used.

- Peter
 
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Old 12-30-19, 02:18 AM
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Most floor tiles are 1/2" thick or thereabouts.
Are they planks with a gap or tongue and groove?
 
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Old 12-30-19, 04:55 AM
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Another option, one that I prefer, is to use the Prova/Ditra styrofoam bed pan and membrane system.

Guaranteed to not leak and much easier to build than conventional mud bed!
 
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Old 12-30-19, 06:49 AM
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Over the floor joists, I think are planks but I have not gotten down to that layer yet. Still dealing with the last 3 sq ft of mud and tile. Then there is the debris to be cleared out and the black paper/roofing felt to be pulled up. I was hoping to pickup the materials for the subfloor before I head home from work today so help me guess what I need. If I am pretty sure there are planks - not tongue and groove. Is that considered the first layer of subfloor and I should add 1/2" over that or do I need to go with 3/4". I was planing to follow that with either Hardie or Ditra and then tile.

- Peter
 
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Old 12-30-19, 10:19 AM
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1/2" plywood is probably enough but it really depends on your floor joist size and spacing.
 
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Old 12-30-19, 07:26 PM
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Sub floor is not what I expected

I removed the rest of the mud and tile and was surprised to see what I think are the tops of the floor joists with pieces of maybe 1/2" plywood between them. Many of those plywood sections are sagging a and I am not sure what they are nailed to. Maybe some of you have seen this style subfloor before and understand more about it.

I am inclined to just throw a sheet of 3/4" plywood over the top and then go to the Hardie or ditra. I know this is assuming the houses are even and level.

Just to make it more interesting, how do I handle the toilet flange? There is a lead inner section they is folded over the top of the flange. I was going to straighten it out and remove the old flange. Then I would cut a hope in the new plywood and slide it over the lead pipe. Do I wait to see the new flame after the Hardie or the tile?

Please comment since I am guessing as I go along.

Pictures

- Peter
 

Last edited by pjaffe; 12-30-19 at 07:53 PM.
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Old 12-31-19, 03:02 PM
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I bought some 3/4" plywood to put down a first layer. On the one hand I want to use the largest pieces to have the fewest seams but also need to go with smaller pieces to fit under the doorway and bottoms of the walls. Is it better to leave it a little short at the end and sides so I can fit it in with fewer cuts.

- Peter
 
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Old 12-31-19, 04:11 PM
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With your pictures I can see that your mud bed was the actual tile underlayment and not a conventional shower install as I originally thought.

The construction is unusual, have never seen plywood that was installed flush with the joists so I think you have to assume it's not structural and the 3/4" plywood is the minimal to install along with CBU
(personally I have never used less than 1/2" others say 1/4 is acceptable).

As far as layout, I always balance the left right and front rear so that pieces are as similar as possible.

Our current house, spec home we purchase, has tile that is full on one side and I kid you not 1" on opposite, looks like krap!
 
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Old 12-31-19, 04:28 PM
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It was pretty common for plywood to be let into the joists and sit on cleats like that. It saves on height and was common on old mud beds.
 
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