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Discussion Starter · #1 ·
Hi folks!

We are about to do a bathroom reno and the existing floor is 3/4" wood plank. It heaves in the middle and slopes to either wall upwards of 1" over about a 4-5' span.

The way I'm leaning toward doing this is:

-5/8" or 3/4" ply screwed down onto plank
-SLC to level out floor
-Install heat mat
-Install Ditra
-Install tile

Or should we swap the Ditra for backerboard and put the CBU down before the heat mat? And then tile right on the heat mat?

My concern is the height. Doing all of this will raise the floor probably 2.5". Is there any way to avoid that? Is the Ditra or CBU necessary, or can I apply the heatmat right to the SLC and ply, and then tile right on that?

Thank you folks!
 

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Discussion Starter · #2 ·
Is the above overkill? Would I be okay to just go...

-Cover 3/4 planks with 1/2" plywood
-SLC
-heat mat
-tile

If I'm using an SLC to cover the plywood, is that adding enough strength to tile right on without raising the height with CBU or Ditra?
 

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bathroom guru
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Have you considered removing the 3/4" planks and replacing with 3/4" plywood? You may be able to fix the slope issue somewhat that way, either plane down the high spots or add shims to low spots...or sister new joists to level off. Depending on the joist size and spacing, I would add a layer of 1/2" ply on top of the 3/4 ply, then heating cables, then SLC, then ditra or stratamat, then tile. The only part of removing the planks that is a pain is the reframing you usually have to do on the perimeter, but, if you want to keep your overall height down, it would be worth it.
 

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bathroom guru
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FreshConst said:
Is the above overkill? Would I be okay to just go... -Cover 3/4 planks with 1/2" plywood -SLC -heat mat -tile If I'm using an SLC to cover the plywood, is that adding enough strength to tile right on without raising the height with CBU or Ditra?
Btw....SLC isn't going to add any strength to your floor.
And, their is no such thing as overkill! Lol
 

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Discussion Starter · #5 ·
Have you considered removing the 3/4" planks and replacing with 3/4" plywood? You may be able to fix the slope issue somewhat that way, either plane down the high spots or add shims to low spots...or sister new joists to level off. Depending on the joist size and spacing, I would add a layer of 1/2" ply on top of the 3/4 ply, then heating cables, then SLC, then ditra or stratamat, then tile. The only part of removing the planks that is a pain is the reframing you usually have to do on the perimeter, but, if you want to keep your overall height down, it would be worth it.
As far as height, wouldn't replacing the 3/4" plank with 3/4" ply be a wash if I'm putting 1/2" over either anyway?

Unless you're assuming I'll be able to level it out and thus avoid the SLC step?
 

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bathroom guru
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FreshConst said:
As far as height, wouldn't replacing the 3/4" plank with 3/4" ply be a wash if I'm putting 1/2" over either anyway? Unless you're assuming I'll be able to level it out and thus avoid the SLC step?
Yes and No! It may be a wash, but you'll have a much stronger floor and if you can level out the joists you won't have to use as much SLC. That being said, I always cover my heating cables with SLC because I don't like setting tiles on top of the bare cables(although it can be done). One thing I forgot to ask/mention is what size/span are the joists and what type of tile are you installing?
 

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First you better calculate a deflection ratio for the material you want to install.Second it is always best to level out a floor with proper framing and substrate.Take it down to the floor joists and start over, as it has been mentioned already.Just my 2 cents.
 

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Definitely strip it down to the joists. It will be a pain that will take a few hours but will save you hours and hours of headache and hassle. I agree with what was said above sister joists to raise the low spots. 3/4 ply then 1/2 hardibacker then heat mat then SLC and tile. You will have a great product at the finish with less headache and risk of callbacks.
 

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Just a side note: Schluter just came out with a heat mat--sort of like a heated Ditra----something to look into---that would save you a step ---(if the cost is not to high)
 
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