1 - 20 of 37 Posts

#### vmcmahon

·
##### Registered
Joined
·
7 Posts
Discussion Starter · ·
Hi Everyone. I am new here and have read alot of posts regarding tiling and specifically the use of Ditra. I am taking on a project to tile an entryway and living area. the entryway will butt up to an existing tile floor.
I need some guidance on how to make up the inch difference to the top of the existing tile. The existing floor used some type of rock board underneath the tile. I always hear faint cracks in certain area's and feel that at some point the old tile will start to show grout cracks etc. I think Ditra is a better option for what I am doing now

The current subfloor is 3/4 ply. The joists are solid, and I did a defleco calculation of 615. The tile is ceramic. 6 * 40 tile.

How would you guys make up this inch.
What should I allow between the Ply & Ditra, and Ditra & tile?

My thoughts are Dirta xl (5/16) + tile (3/8) = 11/16. Will I make up the remaining 5/16 with thinset? - I think that's alot?

Second thought - Plywood (1/4) + Ditra (1/8) + tile (3/8) = 3/4. Is 1/4 more realistic to make up with thinset ?

Would love to hear how you guys would tackle this

regards

vinnie

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
What does 6 * 40 tile mean?

3/8" tile is pretty thick tile. Even if it is that thick, 5/16 is probably too much to expect from thinset. Normally I like to see that inch, because for me that would mean 1/2" plywood, making an excellent 1 1/4" subfloor base. Then 1/8" Ditra, 1/8" thinset (spread with 1/4" square trowel), and 1/4" tile.

1/4" is also a lot to make up with thinset. Realize that to get 1/4" of thinset, then theoretically you should be using a 1/2" square trowel. That's a monster trowel size, normally only for the biggest tile.

I would go with either 1/2" plywood and Ditra, or 1/4" plywood with Ditra XL. A 1/4" trowel will give you about 1/8" of thinset.

#### vmcmahon

·
##### Registered
Joined
·
7 Posts
Discussion Starter · ·
Hi Jeffnc - Thanks for your input

6*40, means the tile is 6" wide by 40" Long. Its the new plank look tile. I verified with the tile store today, it is 3/8 thick.

If I go with 1/2 ply, with 1/8 ditra, and my tile is 3/8 - I will be high - the thickness of the thinset under the ditra and between tile/Ditra

If I go with 1/4 ply and Ditra xl, and tile, and taking into account 1/8 for thinset, I will need to make up 3 /16

How noticeable will the first option (Higher) or second option (Lower) be? I think its too much?

any other ideas?

thanks so much

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
OK, that occurred to me but 40" tile isn't common, so just checking.

Have you thought about what size trowel you'll be using, or is recommended for that tile? You might want to check out some sources.
http://www.tigermountaintile.com/2013/02/18/wood-plank-tile-floors/

You might be getting into territory where you really want 1 1/4" subfloor thickness, to reduce deflection for those super long tiles.

If 40" is monster long. Your floor better be flat and even then you might want to go with that big 1/2" trowel we talked about. To figure thinset thickness, take half the size for square trowels. e.g. 1/2" x 1/2" x 1/2" trowel gives a 1/4" final thinset depth after the tiles are pressed down.

You might want to start looking at transition strips and go for a 1/4" height difference with the 1/2" ply.

#### joecaption

·
##### Registered
Joined
·
37,461 Posts
1/4" plywood should never be used as underlayment under tile.

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
1/4" plywood should never be used as underlayment under tile.
You don't seem to be reading fully.

p.s. you don't have to say "under" twice.

#### gwilkrrs

·
##### Registered
Joined
·
168 Posts
don't worry I am in the same spot- I have a slab on grade and am trying to make up 1 1/2" overall and am laying the 1" hexogon tile mats. I was advised to do a drypack mortar bed that will make up the distance from slab to where the thinset base should be.....

#### vmcmahon

·
##### Registered
Joined
·
7 Posts
Discussion Starter · ·
Thanks for everyone's replies. I feel more comfortable putting down a layer of ply, and then ditra. Its a high traffic area, with large tile so even if its 1/8th higher than the next room, I think it will be ok . thanks so much

#### JetSwet

·
##### Pro
Joined
·
1,020 Posts
jeffnc said:
You don't seem to be reading fully. p.s. you don't have to say "under" twice.
Jeffnc, Joe is right. 1/4" ply should not be under ditra or backboard. It will pucker and you actually loss deflection.

#### vmcmahon

·
##### Registered
Joined
·
7 Posts
Discussion Starter · ·
Jeffnc, Joe is right. 1/4" ply should not be under ditra or backboard. It will pucker and you actually loss deflection.
Hi JetSwet........ Thanks for your post..... What do you think would be the best approach to make the inch I need? Should I go with the thicker ditra xl?

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
What are you talking about? Puckering from the screws? It should be screwed to the floor on a close schedule. Puckering can be a problem if covering with vinyl directly, but Ditra is going on top of this. If puckering becomes a concern, then the 1/4" plywood should be stapled instead of screwed.

As far as "loss deflection" - whatever that means - if you're trying to say you will "lose deflection", you're actually right. Adding a structural element such as plywood will reduce deflection, which is a good thing.

#### JetSwet

·
##### Pro
Joined
·
1,020 Posts
jeffnc said:
What are you talking about? Why would it "pucker"? That makes no sense. It should be screwed to the floor properly. Plywood is a laminate product. The laminated sheets are the same thickness and glued the same way in 1/4" plywood as in 1/2" plywood as in 3/4" plywood. There's no reason for anything to "pucker" - unless it gets soaking wet, which plywood is never supposed to do, and even then all plywood would have a problem, not just 1/4" plywood. As far as "loss deflection" - whatever that means - if you're trying to say you will "lose deflection", you're actually right. Adding a structural element such as plywood will reduce deflection, which is a good thing.
1/4" is too thin... minimum is 3/8 or 1/2". When you screw down that thin of plywood you will get duvets so between your screws will pucker up. I meant you will have more deflection with 1/4" because it's too thin.

#### JetSwet

·
##### Pro
Joined
·
1,020 Posts
vmcmahon said:
Hi JetSwet........ Thanks for your post..... What do you think would be the best approach to make the inch I need? Should I go with the thicker ditra xl?
Instead of 1/4" ply use 1/4" cement board then your tile or... 1/2" over 3/4" then tile but you will need a very good modified thinset and a. BC sanded plywood. This is entry way hall way not a bathroom. You would have. 1-1/4" totally ply if done correct can work.

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
1/4" is too thin... minimum is 3/8 or 1/2". When you screw down that thin of plywood you will get duvets so between your screws will pucker up.
Do you know what a duvet is? Use staples if puckering becomes a problem.

I meant you will have more deflection with 1/4" because it's too thin.
Adding more structure is not going to increase deflection in the subfloor. Unless you're trying to say the "bubbles" will cause some kind of micro-deflection, but that's not what's meant by deflection.

Of course cement board or Hardibacker can be used under Ditra, but it's not structural. If you just need more space, then Ditra XL would work fine.

#### JetSwet

·
##### Pro
Joined
·
1,020 Posts
I wouldn't suggest 1/2" cement board because again... you will loose support and gain deflection. You do not want any weakness between sub floor and tile. 1/4" cement board is the lets say Goldilocks zone.
Deflection is not only between joists and plywood it's also between tile and plywood.
The OP can use 1/4" plywood or 1/2" cbu but I guarantee the grout will crack.

#### jeffnc

·
##### Registered
Joined
·
8,298 Posts
I wouldn't suggest 1/2" cement board because again... you will loose support and gain deflection. You do not want any weakness between sub floor and tile. 1/4" cement board is the lets say Goldilocks zone.
Some of the things you say just make absolutely no sense at all. And I'm not even talking about your atrocious spelling or grammar which we have to suffer through to figure out what you mean.

How on earth is adding 1/2" cement board going to decrease support and increase deflection? This makes no sense at all. And you're saying adding 1/4" cement is somehow going to be better? Cement board does basically nothing to change that equation.

And if anything, Ditra is going to help, as a decoupler.

#### oh'mike

·
##### Retired Moderator
Joined
·
25,770 Posts
This is beginning to turn into a personality clash and less than helpful.

To the OP---please, do this first---check the floor for flatness----those long tiles require a pool table flat surface.

Do add plywood to give you enough stiffness---an,as mentioned, 3/8 inch thick is the minimum ----1/4" thick can pucker ,leaving voids and leading to failure.

I'll be watching this---------try to stay focused on helping---Mike------

#### ddawg16

·
##### JOATMON
Joined
·
17,232 Posts
I'm going to have to question the claim that 1/2 of plywood is stiffer than 1/2 Hardibacker.....I had a quick check and I need to confirm some number conversions....but I'm thinking Hardibacker might be as stiff if not stiffer.

Of course an easy test is to take a 4' long piece of each....suspend it on the ends....and put weight on it and measure deflection.

#### JetSwet

·
##### Pro
Joined
·
1,020 Posts
ddawg16 said:
I'm going to have to question the claim that 1/2 of plywood is stiffer than 1/2 Hardibacker.....I had a quick check and I need to confirm some number conversions....but I'm thinking Hardibacker might be as stiff if not stiffer. Of course an easy test is to take a 4' long piece of each....suspend it on the ends....and put weight on it and measure deflection.
Hardibacker and other cement boards hold no structure for tile. It's to bond the tile to plywood. If you have to much bond of void between ply and tile you will gain more movement between tile and plywood. Your tile will stay put but movement will result in grout crack.

1 - 20 of 37 Posts