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Discussion Starter · #1 ·
I an in the process of installing a perimeter drain in the basement and when i am done i am thinking about putting tile down on the slab i am thinking about using ceramic tile and ditra backing to give it a water tight seal now that my water problem is fixed any thoughts about sub floors or thinset or different types of tile is apreciated because i have not done tile before thanks adam
 

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Tile can be installed right over the concrete slab---no 'sub floor' needed or wanted.

If you want to use Ditra ---that is good insurance--but is not required--

Jaz and some other members have experience with Ditra--If they respond--pay attention.

As to thinset--you want a powdered, modified thinset---if you are going right over the slab.
 

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I don't really see the reason for
a) Ditra over slab
b) a water tight seal over a drained slab

I suppose the design and reason for your perimeter drain would affect this. Ditra can be used over a slab but normally that would be more for crack protection than waterproofing. I don't see the need for waterproofing, but if you explain, we can get you there perhaps with Kerdi in addition to the Ditra.
 

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Now you have shown us a good reason for the Ditra---it will act as an isolation membrane-----

your slab is not in great shape ,if that picture is typical of other areas--are any of the cracks lifted or sunken ?

One of our members, Jaz , is very knowledgeable in the Ditra--if he sees this thread,pay extra attention.
 

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Discussion Starter · #6 ·
No no spots are lifted or sunk no real big gaps either its either i 1st re surface the floor or i 2nd paint it or my 3rd option is tile and if i can and it works the way i want i think the tile will be better than the other 2
 

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Thanks for clearing up my confusion--I thought tile was your first option---

I don't know much about polishing or resurfacing concrete---

Paint and tile I know.
 

· Tileguy
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Hi Hurley & guys,

Ditra is a fantastic product but it's not gonna do some of the things you mentioned. Ditra is not gonna keep liquid water from coming up through the floor. You don't have that problem now, do you? The best it can do in this regard is to equalize excess moisture, (to a degree), so the moisture will be spread over a large area, then evaporate through the channels and out the perimeter. It can also save an installation by isolating your in-plane cracks from the tilework.

Do you have a moisture problem, any visible water trickling in ever? Musty damp air? Ever do a moisture test? How's the soil condition/type and weather there, ground elevation etc.? That's one reason we ask you to list your location in your profile, it can really help.

In addition to cracks, do you have expansion joints? How old is this slab?

1. What do you mean by "re surface" the floor, is the floor very flat?
2. Paint a basement floor? Please don't do that, it's a very bad idea.

We need to know alot more and I'd like to see more pics if possible.

Jaz
 
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Personally, I would use Ditra over cracks like that.

I should point out thought that Ditra (last I asked) does not warrant Ditra specifically for that purpose. Technically you need a crack isolation membrane, and Ditra is not marketed exactly as that. It's not intended for existing cracks, it's intended for potential movement or even cracking in the substrate after installation.

That might seem like an overly fine point, and I'd agree with you. Frankly I think Schluter just does that to cover their ass, and Ditra would work fine in that situation. I know other tile guys as well that would not hesitate to use Ditra in that situation regardless of what Schluter specifically warrants, simply because Ditra works pretty well at that.
 

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Theise are some of the cracks i have i was thinking about the ditra mainly to seal thiese and hrlp keep it air and water tight
You can't and really don't want to keep it air and water tight from the top. I wouldn't hesitate to use Ditra, but waterproofing the slab from the top side would not be the goal. Your tile will survive fine if some moisture wicks into it. Tiled showers floors work just fine after all.
 

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Discussion Starter · #11 ·
I live north of grand rapids michigan i do not have a problem with water coming threw the slab i did have water coming between the slab and block but i am fixing that with a interior parameter drain tile hooked to a sump pit the slab is about 28 years old the resurfacer i dont know the name ill look it up but it goes on 1/8th inch thick and creates a new top coat to seal all the cracks.
 

· Tileguy
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Forget about the resurfacer to fill the hairline cracks. You're not painting the floor plus how would you keep it ⅛" thick? A vinyl concrete patcher is not gonna "seal" the cracks, plus you don't need to.

You need the floor to be flat within ¼" in 10 ft. for most ceramic tiles. I can't tell from the pic in #4, is that an irregular crack and how wide and is it level on both sides? The color doesn't look normal, or is it cuz you used your phone?

Ditra will help with small in plane cracks. Are there any expansion joints or cold joints in the floor? Or was in poured in a monolithic form?

Jaz
 

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Discussion Starter · #13 · (Edited)
The floor might have been primes and i have the carpet backing that stuck to the concrete do thats why it looks like that and the re surfacer is like a self leveling cement and i would end up doing the whole 1300 square feet 1/8th inch thick if i went that way. And as for my cracks yes they are hairline and they are level
Also i don't have any expantion joints the blovks were put on the footers and the slab was pored 4 inches thick
 

· Tileguy
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There is no way for you to pour SLC a constant ⅛" thick even if the floor was level, can't be done. You'd end up with some areas fairly thin, while other might be much thicker. SLC needs help to flow. If you hired a professional company to pump it, and the floor was fairly level, (but not flat) you'd likely have well over ½" and prob. more closer to 1" of material on the floor. All depends on the floor and their skill. You can't just say you need it ⅛" and expect it to happen.

You need to start thinking is the floor "flat", and if not how out of flat is it.

Jaz
 

· Tileguy
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That's an open ended question and impossible to fully answer without knowing your skills and the condition of the floor.

Start by answering the questions you've been asked starting with is the slab very flat and its condition. Hopefully you'll be able to ask specific questions and not generalize. Also let us know what specific type and size tiles you're using and if you plan to use Ditra as stated.

Jaz
 

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Check out the installation guide for Ditra, paying speciall attention to the crack comments on page 11.

https://sccpublic.s3-external-1.ama...8815748186142/DITRA Installation Handbook.pdf

Actually now that I think about it I'm not sure why unmodified thinset is recommended to adhere Ditra to the concrete substrate, but that's what it says. Use a high quality thinset - a cheap one costs $8 and a good one costs $13 which seems like a lot percentagewise but it's only a few bucks for the overall cost of the project.
 

· Tileguy
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ahurley said:
Yes i was going to
When asked if Ditra is planned.

Wow, 1300 ft. of Ditra for your basement, you're a dream client who obviously wants to do it right. Where were you when I was still installing tiles.:wink2:

Jaz
 
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