# ditra over hardiebacker?



## JazMan (Feb 17, 2007)

Hi, how about a name to call you by?

Sounds like being the "ex" was well deserved. You need to remove the Hardie attempting to salvage if possible, and start over with someone that is a tile setter and not a handyman. 

It sounds like the subfloor needs help too. Hardie, or any CBU without thinset under is a fatal mistake that will results in cracked grout at min. or cracked tile eventually. You might be ok for a few months or even a few years, but it will fail....guaranteed. 

I've seen it hundreds of times including the repair I'm doing right now. This job should all be ripped out, but it would be costly so I'm trying to give the customer a few years. Do it right, you're not too deep yet.

Let us know what's going on.

Jaz


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## JetSwet (Jan 21, 2012)

Jazman is right this is unfortunate but good that you caught it in time was this floor installed from joists up?

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## magdacap (Jan 24, 2012)

Thanks for replying Jaz. My name is Magda, you can call me Maggie.
Here is th story:
I hired a "pro" to install my kitchen tile and obviously prepare subfloor. As I watched, he prepared my playwood sub (looked like a thick sandwich of ply,vynil, ply) by adding some modified thinset mix to the areas that he thought needed leveling, then place all the hardiebacker sheets and screw them to the plywood. I though he needed to add thinset all under the hardie not just some areas so next day when I was going to complain he actually had added thinset to the hardie board joints without puting tape. So, this is when I asked him to stop and I went online and spent hours on researching. My conclusion is that he did all of it wrong and that if I install my 12×24 expensive porcelain tiles on that sub they will crack for sure. He swears and stomps thru saying the floor is sound and ready and that he had never had set all cementboard with all thinset under. Also, a Home Depot guy actually backed him up saying the tape was not required! I am very concerned as I saw the thinset on the hardie joints go in and delineate the joint again as if the thinset was going inside and (maybe under?) de hardie board.
So, I sent him on sabatical and decided to fix this mess. I thought on 3 optons:
a) demo everything and start again – not my choice as the screws will b a nightmare and t will cost me some bad sweat, time and money
b) scrape the thinset on th joints (it’s coming off sort of easily) , put more thinset and tape.- I am still concerned by the non-thinset layer under all the hardie boards
c) install ditra on top of the installed hardiebacker boards using unmodified and then tile using unmodified.
I already bought Ditra and am ready to move with C but I think your thoughts would be very beneficial in my current state of mind.

Why would ditra on hardie be a bad option? JUst want to understand, I am new to tiling science but I learn very fast. 
If I do the demo.. should I redo with Hardie or just do the ditra over the plywood. Also, he did an irregular patch of modified thinset over a plywood filled space where the base cabinets were located. Other than that the plywood was clean on top and flat and even leveled. 

I am traumatized on hiring a pro now... I may just give it a shot myself and follow the instructions carefully instead of throwing my money away again.

Thanks for all your help!!! I hope you can sense my angst and forgive my long message.


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## JazMan (Feb 17, 2007)

Maggie,

Yes I feel your angst, here's a virtual hug. :thumbsup:

Remove the Hardie and take it to the curb. You can not simply install the Ditra over the improperly installed Hardie and expect it to work, long term. Then prepare the plywood subfloor as needed to make it flat and refasten well. Once you're happy, install Ditra using a good modified thinset per directions. Then install your tiles using a premium unmodified mortar per Schluter's wishes. A modified mortar will work fine too, but you loose any Schluter warrantee if that matters to you. 

Let us know what specific brands are available to you there.......and where there is.

Jaz


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## JetSwet (Jan 21, 2012)

Did you just say ply, vinyl, ply sandwich?!
If this is the case I'm am going to have to question reality lol

Sent from my iPhone 4 ios5


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## magdacap (Jan 24, 2012)

Thank you Jaz and JetSwet as well for helping me out. 

Yes, I said Ply, Vinyl, Ply... Looks like some smart person wanted to install the cheap Vinyl (the one I took off in a second) and decided to add plywood instead of taking the old one off. Maybe they had those hard to remove vinyl squares. So what I found when I bought the house was a 23x13' kitchen with ply subfloor of vinyl sandwich. Nevertheless, the plywood on the top ws in pretty good flat condition with the exception of the areas where the cabnets were located. So, the contractor filled in those spaces with more plywood, leveled with modified thinset and screwed up the Hardie... twice...if you know what I mean. He used Versabond. I got unmodified in HD... they just have one brand... maybe a bad one I presume. Lowes is an option for me too. They have Megabond, would that work?
I guess I'll remove the hardie.. the screws are my biggest nightmare.

I think there will be patches of the thinset... what to do with those? just make sure they are flush?

THANKS REALLY REALLY A LOT!


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## magdacap (Jan 24, 2012)

Oh, and I live in NJ near NYC. If you happen to know a good tile setter here please let me know!!


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## JetSwet (Jan 21, 2012)

So you took the vinyl up before the second layer of ply was put down I'm sorry I hope I'm reading it write.
Any filler like cement board or ditra needs to be put in a bed of thinset the mesh tape is to be done as well similar to sheet rock you need to tape the seams. 
You need at least 1" of wood from joists up.

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## magdacap (Jan 24, 2012)

Yep. It was vin,ply,vin,ply,joists. Now is hardie,ply,vin,ply,joists.
What a highly treated floor agh?


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## JetSwet (Jan 21, 2012)

magdacap said:


> Yep. It was vin,ply,vin,ply,joists. Now is hardie,ply,vin,ply,joists.
> What a highly treated floor agh?


Lol that's like a combo deal meal #4 with extra vinyl lol

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## JetSwet (Jan 21, 2012)

It sounds like you really know your floor though which good.


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