Schluter Ditra Underlayment prevents cracks in ceramic floor tile

Published by Millennial1 on April 19, 2007 - 2:24am

Ceramic floor tiles and marble can crack if your sub floor is not very sturdy. Schluter Ditra underlayment should be used to ensure that this doesn't happen. The Ditra Installation Video and installation handbooks ensure success.

Concern with Bathroom or Kitchen Floor
Cracked ceramic floor tiles are difficult to repair, so we wanted to do everything possible to prevent cracking. In our home kitchen remodeling project, we were concerned with the rigidity of our kitchen floor. The space was approximately 13 feet by 27 feet. As shown below, our sub floor was made of planks and on the advice of a ceramic tile installer, we put in 3/4 inch plywood, which we screwed in.

The plywood added rigidity, but the floor was still spongy when we jumped up and down on it. To complicate matters, another ceramic tiler said that we should have installed 1/2 inch Durock which we had used in our bathrooms. To make matters even worse, the transition between the kitchen and the adjoining rooms was becoming an issue.

Subfloors in kitchen

Solution: Use Schluter Ditra
Profile of ditra, unmodified thinset and tileSchluter Ditra is an orange polyethylene mat with square, dovetailed recesses and an anchoring fleece laminated to the underside. It is as light as a feather and much easier to work with than Durock. Ditra really addressed our two major problems:

  • provided adequate support and load distribution for the tiles, and
  • Was only 1/8 inch thick, which minimized the kitchen floor transition problem.

Other Recommendations
Make sure you supervise the Ditra installation if your tiler has not worked with it before. Many ceramic tile installers are not familiar with and most are not going to read an installation manual either. So you have to do your homework.

Ditra installed in bathroom to prevent tile from cracking

The biggest mistake that a ceramic tiler will make is to insist on using a modified thinset to install the Ditra on both the sub floor and also to install the tiles. This is not correct. So hold your ground.

In the case of plywood sub floor, You can installed the Ditra on it using a modified thinset which has an additive in it. However, only use unmodified thinset to set the tiles on the Ditra. Unmodified thinset has no additives in it. It is dirt cheap also. For all other floors, following the instructions in the Ditra Installation manuals. They come in English, Spanish and French and can be fouund at the Schluter Downloads page.

Also watch the Schluter Ditra Installation Video which is about 8 minutes long. It won't win an Oscar, but you'll have a good idea of how to work with the Ditra. Good luck.


I plan to tile my Florida room floor which is a concrete slab. The room is heated and cooled year round. The floor has no real abnormalities. Should I go to the extra expense of putting down DITRA as an underlayment or can I save the expense and just use self leveling thinset and then tile? The floor is 16' x 16' .

Thanks, Jer

I don't think that you really need to use the Ditra if you have a very stable surface and are installing a 12" x 12" tile. We had a similar situation with our concrete basement floor and didn't use Ditra at all. We installed a 12" x12" Italian made tile.

If you are going to use some of the larger tiles than you have to make extra sure that your surface is level. If you don't, that could cause a problems in the future. The self leveling material should do fine though. Here's an article from the Ceramic Tile Institute for the larger formats 16" x 16" and larger.

In our kitchen, we used Ditra because we were very concerned about the stability of the wood floor. It has worked fine.


After careful consideration, I did purchase the Ditra. As expensive as the tile was-I wanted to ensure that I had a smooth and more level surface to work with. The concrete slab has several seams that aren't exactly even with each other and with the 18" tiles, I had concern of cracks in reference to not knowing where the tiles might meet the seams. I do plan on setting them in diagonal for effect.

Thanks again for your advice and I'll stay in touch with the finished product.


It's been a little over a month and I'm nearing completion of my project. I took my time since I was in no hurry and juggling a busy schedule kept me away from the project for a few days. I am very pleased the way it turned out and I'm glad I put the extra expense of adding the DITRA. I only have the grout to add and it's done.

The Ditra was very easy to work with and I recommend using it for floors that have existing cracks and flaws. I do suggest totally covering the floor with the thin set unmodified mortar and pre-cutting the sections prior to installing.


Our installer just layed the detra mat and we are know waiting for him to come back and lay the porcelain tile. We have discovered a squeak in the floor.There are 2 sub floors and detra mat. Should we be concerned about the squeak?


I tiled about 1500sq feet of tile and used Ditra as underlayment. In several locations I have grout powdering up and cracking out. I have replaced the grout once already. I do have radiant heat in the floor, but it is attached below the wooden subfloor. Should I have used a special grout or additive. HELP.

I'm considering using Ditra on a floor tile install. I'm tearing up an old 6" x 6" kitchen tile floor I installed over 20 yrs ago. The initial install was on a 3/4' plywood sub floor over a tung and groove hardwood floor. I used thin set with an acrylic mixing agent.The floor has stood the test of time. Anyway it's time for an update. The guys at Home Depot are suggesting using 1/8" backer board (after the time is ripped up) and using thinset and screws to fasten the backer board to the sub floor. Then thin set the 12 x12 tiles to the backer. I'd like to use the Ditra but not having any experience with it I'm not sure if it is the right product.Can you give me any feedback as to whether the backer board or Ditra is the right way to go.


If your old 6 x 6 didn't have cracks then the flooring was fine. Yes you are using 12 x 12 but that should be fine. The guys at home depot are probably thinking that with the 3/4 inc subfloor over the old hardwood floor that this is sufficient. I agree. The ditra is an insurance policy against cracking so it is really an option. So if you are not concerned with cracking then the backboard should be fine. If you are then use the Ditra instead. Also you didn't mention the transition with the adjacent floor so I am assuming it's ok.

Hope this helps.

I am trying to find out if I need to use a latex modified thinset to put down the ditra. I am using your product in my bathroom which is in a summer cottage on concrete piers. We are on the water and this tends to create moisture since we have tried to close in around the piers to help with insulation. Your paperwork says to lay the Ditra with a latex modified mortar and then to use a non-modified mortar to install the slate flooring. I want to verify that this is true for a house on piers without a basement. We read somewhere that latex modified mortars can create mold so we are concerned about that is a house that has dampness issues because of location (on the water). Please HELP!!!!!!

I have not heard of that mold issue with the Ditra. I understand that you have concrete piers but it the floor of the bathroom floor is plywood than go with unmodified thinset? If not then it it is best to printout and read thoroughly the brochure at There is a section on each type of floor and it should tell you what you need to know.

Just so you know, we don't work for Schluter Ditra, we just use their products and find them useful.

I recently remodeled our kitchen and added 6' and a new dining room. Our home is on peer and beem. I have not installed any flooring yet. During the winter months I have noticed that the new addition and old area seam sperates alomst and 1/8" due to temperature variances. I want to insure that using the Ditra product solves this problem when I install the tile. Will it Work?



I contacted Schluter Ditra about your situation. Here's what they said:

Yes DITRA will help eliminate the transfer of movement from your substrate to your tile service. A couple of things to keep in mind is that the DITRA will have to have to be separated at the joint where the new and old slab meet and then you will have to follow through with a movement joint in your tile field (we have dilex profiles) to allow for the movement as well. You can view our DILEX profiles on our website at the following link

Dilex Profiles at

Please let us know if you have any further questions. Thank you and have a great day!
Best Regards,

Shawna Arno
Customer Service
Phone (800) 472-4588
Fax (800) 477-9783
csrusa at