How to Tile a Floor Using an Underlayment Membrane

Floor tile are commonly made of either ceramic or porcelain:

  • Ceramic Tile: Long considered the standard in floor tile, ceramic is made from fired clay with a glaze coating. While often less expensive than porcelain, ceramic tile is not as durable.
  • Porcelain Tile: This tile is composed of sand which is fired at high temperature and pressure. Since it isn’t porous, porcelain tile is more water resistant and harder than ceramic, but it is harder to cut.

When installing a tile floor, a layer of cement backer board is usually put down over a plywood subfloor to provide a firm, stable surface. A waterproof underlayment membrane like Ditra from Schluter Systems can be substituted for backer board. Made of lightweight polyethylene, the membrane is only 1/8” thick and can be cut easily with a utility knife.

When using the membrane:

  1. Cut the membrane to size.
  2. Apply a layer of thin-set adhesive fortified with latex to the subfloor.
  3. Roll the membrane out, and position it in place.
  4. Apply a bed of thin-set without latex additive, and set the tile in it.

Tiles can be cut using a hand operated “score and snap” cutter or a motorized wet saw.

After the tiles have set, apply grout to the joints using a rubber float. Grout is available in a variety of colors, but darker grout stains less. Stainproof grout is also available.

Once the grout has set, apply a grout sealer to the joints to prevent stains from occurring. If grout has already become stained, a grout stain pen can be used to stain the grout a uniform color.

43 COMMENTS

  1. i have a ceramic tile floor in the kitchen and tearing it out it’s on plywood subflooring.would i have to put a
    membrain down for the new tile????

    thank you mike

  2. Mike…

    You’ll need either the membrane or a cement back board. Your choice. For a kitchen floor, I’d recommend a 1/2″ backerboard. The membrane will also work. It’s certainly easier to cut and maneuver, but more expensive.

  5. I have a house that the builder put particle board in all areas except wet areas there they used plywood, now I want to use ceramic tile in all areas how can I do this without pulling the particle board? Thank you

  6. Is there an adehesive for grout. I put tile down over a cement backer board and the grout keeps breaking up.

    What is the best tool for cutting out a outletbox in porcelin tile. I tried with a tile saw but it is 3 inches from the edge and the tiles keep breaking.

    Thanks

    • Hi Jerry,
      Grout should adhere well to both the tile and cement backer board without an adhesive. You might try using another brand of grout or a new container in case yours has gone bad. To find out more about cutting tile, check out our Ask Danny article on How to Cut Tile Around Electrical Outlets. We also have a video on How to Tile a Bathroom Floor that demonstrates several methods of cutting tile around openings. Good luck with your project!

  7. i have a small 5 1/2 by 5 1/2 bath. i want to tile with the small hexagon tile that is on a mesh background . it is a wood subfloor .do i still have to use cement backerboard . i am a 67 year old female and dont know if i can handle backerboard.

  8. Love this site but can’t seem to be able to open and get the answer people are looking for… I click on the date and nothing happens…How do I see the answers???? thanks so much LOVE!!! Danny’s show even though I don’t do a lot of the things he shows…just interesting to see a finished project…in the middle of new tile and hardwood where old hardwood was!!! Glad I don’t have to make a living doing it!!! 🙂 Have a great day!

    • Hi Debbie,
      Unlike a forum, the comments posted under a particular article on our site are shown as one long list with the oldest at the top and most recent at the bottom. Clicking on the date doesn’t really do anything. If someone responds to a question that was posed in another comment, it will appear on the date the response was posted, not as a drop down from the previous comment. Comments posted by members of the Today’s Homeowner staff appear in yellow with the Danny Lipford logo next to them.

  9. Flo,
    Maybe this is late, but since the expert hasn’t responded, I thought I would jump in. If your subfloor is plywood you will need to lay down something as plywood will expand and contract causing your tiles to crack and/or pop loose. You can either use cement backerboard or a waterproof underlayment membrane. The membrane would be much easier for you to work with as it is thin, lightweight, and flexible, and easy to cut. It is more expensive but you have a small area you are tiling so it should be doable. You can find the membrane at any large local do-it-yourself stores. I am female, middle-aged and have some physical challenges myself and it is the way I was planning to go in my similar-sized guest bath before discovering I could tile directly over my vinyl flooring which is tightly adhered to the cement slab (YES!).

  12. Hello,
    I am finishing my basement and have built a bar down there. I am going to tile around the bar area. The floor is concrete but i did put down a plywood subfloor, just around the bar area, as i thought this would help level off the floor a bit, as the concrete floor underneath is a bit uneven. I am thinking of putting this Schluter membrane system down on top of it to be sure i dont get any movement and cracking of the tile. Well now, after reading most comments on here, i am thinking i didnt need the plywood?? Can anyone help as to what i should do for the best?? I am willing to pull up the plywood if needed, as it didnt cost too much.
    Thanks for any help in advance!

    • Hi Chris,
      You can lay tile directly on a concrete slab without any additional subfloor or membrane. To fill in any low spots in the slab, apply a floor patch or leveling compound before tiling. Once the leveling compound has set, apply thin-set adhesive to the slab with a notched trowel and tile. To find out more, watch our video on How to Level a Subfloor, and read our step-by-step article on How to Lay a Tile Floor. Good luck with your project!

  14. I want to retile my bathroom floor.There is tile over wire mesh over plywood now.I want to rip all this out. Can i fasten backer board over the tung and grove floor or do i have to add plywood first.I want to keep the new tile as flush as i can with the other floors.

    • Hi Mark,
      Since solid wood flooring is subject to movement due to changes in temperature and humidity along with warping and cupping, the best approach would be to remove the solid wood floor and put down a plywood subfloor followed by cement backer board then tile. The second best approach would be to apply a layer of plywood over the solid wood flooring followed by cement backer board then tile. However, the bathroom floor in the house I bought was tiled three or four years ago with is cement backer board over solid wood flooring, and so far it has held up fine. Good luck with your project!

  15. Am redoing my kitchen ,bath,laundry room floors in my trailer ( its a 14×70, 1975 era)with ceramic tile. Currently it has vinyl flooring throughout.I have been advised to use an uncoupled membrane.
    My question is , should I remove the vinyl flooring prior to installing the membrane?

    Thanks a bunch ,Dale

  16. I am re-doing a 2nd floor bathroom in a 1950’s house and jsut ripped up the cement flooring (it was suprisingly easy. I have a few questions if you don’t mind.

    1. Can i put plywood right on top of the floor joists? What thickness should I use?
    2. I was going to use cement backer board and an underlayment membrane, is this a bad idea or completely un-necessary?
    3. How do I go about installing the marbe door threshold? Thinset on the cement backerboard ok?

    Thanks in Advance!

    • Hi Blake,
      In answer to your question.
      1. Yes, you install the plywood subfloor directly to your floor joist (screws hold better than nails).
      2. Apply either cement backer board or an underlayment membrane on top of the plywood, you don’t need both.
      3. Yes, you can attach the marble threshold to the backer board with thin-set.
      You can find out more about tiling in our articles on Installing Tile Over a Wood Subfloor and How to Lay a Tile Floor.
      Good luck with your tiling project!

  17. Hello and thanks for taking my question.

    I wish to tile my laundry room that currently has glued down vinyl flooring over 11/2 inches of sub flooring and a 1/4″ sheeting to make a smooth surface for the vinyl. Hence my question: Can tile successfully be laid over the vinyl and if so what preparation should be made to the surface and can thin set be used ?

    Thanks, Rick

  18. We are wanting to lay 24×24 marble tile over our existing stained concrete. Do I use the Ditra and can it be installed over the stained conrete?

  19. I’m converting a 2 1/2 car garage into a large rec room. The garage floor is uninsulated concrete slab. Existing concrete in great condition with no cracks. Is underlayment membrane necessary to avoid tile/mortar cracking from freeze/thaw of slab during extreme winters? What if I use outdoor rated tiles and mortar? Can I then apply direct to slab without underlayment memnbrane? Getting conflicting info – Thanks in advance for thoughts.

  20. Thanks for taking questions! Is it okay to put level quick on top of cement board prior to laying ceramic tile? Thanks so much for any advice or guidance.

  21. I have been in the tile business for 40 years. A friend has me doing work on his house. His builder did not know he was putting tile flooring on the 2nd floor. If I install hardibacker over thinset, and then the tile, the top step finished height will be much higher than the other steps. This will not meet code. Can I use a liquid waterproof membrane directly over 2 layers of 3/4″ plywood and then install the tumbled 16×16 travertine directly over the membrane? This would solve the code problem

  22. 10 years ago I had tile installed over wood floors. Used cement board. T he 1st crack appeared 3wks after installation. Now I have cracks over ever joist in my kitchen . In our den the floor actually snapped and cracked (sound) in the winter. I put down a 12 x 16 area carpet and that noise has stopped. I have not seen cracks (actual) in that area of the room. I have been told that Ditra overlay would help over the joists,allow tiles to “slide”. Is this correct?

  23. If the cement board was screwed or nailed every 6-8″ every 16″ on center with 1/8″ gap between staggered sheets and the joints were taped with fiberglass tape, there should not have been cracks in the floor. Ditra would not help the tiles to slide, but would be a membrane that causes the floor to flex when properly installed. These products, if used exactly according to the manufacturers installation instructions guarantee you that your floor will not crack. A few years ago you were not required to thinset the backerboard down. Today, they want it installed over a bed of thinset. The same goes for the Ditra.

  24. I am installing travertine tile in a bath and laundry room, my question is since I have 3/4 OSB down as subfloor. Should I use 1/4″ perma base with the ditra underpayment? Is it ok? Would the perma base give me added strength and the dirt the flex I will need?

  25. I am thinking of installing tile in the kitchen and other areas of the house. In one area of the house we have 4 foot on center floor joists and in the other we have 32″ on center floor joists. Do I need to get under the house and give more support to these areas or can I install backerboard to get the same result (no cracking of the tile or grout after install)?

    • Hi Charlie,
      I’ve never heard of floor joists further apart than 24″ on center, you must have quite an impressive subfloor! When applying tile, the subfloor needs to be very firm with no bounce when you jump on it. Otherwise, the tile will crack over time due to movement in the floor. That usually calls for the right width and center of floor joists for the span, topped by at least 1 1/8″ of subfloor (that can include a layer 1/2″ cement backer board). Since your framing isn’t the conventional 16″ or 24″ on center, I would go by the bounce test to see how firm the floor is. Good luck with your project!

  26. Hello,
    I just pulled up 3 layers of flooring and got down to hardwood flooring directly to the joists I had already bought tile and the ditra underlayment thinking I would hit subflooring.. I would rather not pull the hardwood so would I just put down plywood subfloor then the ditra. Thank You for your Help!

  28. Hello!

    I am not sure if this post is still running, however, my boyfriend and I desperately need some help! We just put in new cabinets and granite counter top, and are on to redoing the floor. We have now realized that we can’t lay our ceramic tile on the particle board floor. We definitely do not want to remove the cabinets now. Is there anyway to go around this? We heard that a toe kick saw gets the particle board out and we can put down 5/8″ plywood and ditra and then set the tile on that. Would you agree? Would this be strong enough for our ceramic tile? The floor joists are 2×7, 14′ unsupported span, 16″ apart.

    Thank you so much!!!!

  29. I am planning to tile a room with ceramic tile 8″ by 24″ over plywood subfloor. The subfloor is over a crawl space and the room has moisture issues. Would a membrane work better than cement backer board?

  30. Leveling a wooden sub floor for ceramic tile placement in the kitchen; please instruct how to level this sub floor that has a high level in the middle and lower area at edges with a difference of about 1in at edges. Room is 7 x 11 feet in an old building condo. What to do before laying the cement board for the tile? Thanks for any help, Anna

  31. I am building a shower pan which will go six inches up a wall on the sides how do I seal up the seams of the corners of the pan with schleuter Kerdi ditra underlaymenrt Over laps ? adhesive ?Thank you

  32. To anyone watching the video: Step four, above, when you apply the thin set with the notched trowel, you should use the trowel to create parallel lines, not curvy. When you place the tile down you should press and slightly move the tile back and forth in a motion opposite the parallel lines on the back of the tile. (If you’re facing the tile and your lines are straight up and down, wiggle the tile sideways as you place it.) In this way you will smear the thinset evenly into the ‘tracks’ between the lines. If you combed the thinset into curvy shapes there will be gaps remaining, and those gap spots can cause cracks when pressure is placed on them. (Imagine a woman’s stiletto heel coming down on a gap instead of solid thinset/tile. The tile will break.

  33. I’ve had a Professional Flooring Contractor replace my “water damaged” LR carpet/padding with “wood plank” Porcelain Tile.

    Because this was considered an “upgrade” not covered by my Condo Insurance, the porcelain tile was ‘out-of-pocket’. We selected the Tile and Grout colors. The contractor provided a bid which I shared with the Condo Mgmt. as time was of the essence (bare concrete floors over 60 days).

    Of course, the contractor wanted to get started right away. They sent a “Professional Estimator” to write-up that order. Having submitted the contractor’s bid with no clear objections, for a month, from the Condo Mgmt, I gave the Contractor the ‘go-ahead’.

    Now, two months after the installation, and after having submitted a tile sample, the Condo Mgmt now informs me that a ‘soundproofing underlayment’ is required. Since I’d never heard of an underlayment over “concrete” in conjunction with ceramic/porcelain and mortar installation – I’ve started to research and found that in Multi-Family Dwellings soundproofing ‘can be’ required.

    QUESTION: Should the Professional Estimator and/or Professional Tile Installer have recognized the soundproofing ‘requirement’, as certainly I, the homeowner would not? I have not approached the Contractor, as I’ve just discovered the predicament. PROBLEM #1: I personally cannot say that the Contractor did NOT use an underlayment or ‘special mortar’ during installation; and PROBLEM #2: Contractor’s original bid did NOT have “underlayment” specified (by check box).

    What do you think?

    BTW: This Condo is concrete construction with a 10′ height difference between floors with the ‘finished’ ceiling dropped to accommodate concealed utilities and ducts, etc., it doesn’t seem likely that I’d ever hear sounds from overhead.

    • Hi, Berry,
      Thanks for sharing your situation. We focus on home improvement advice and respectfully try to avoid determining whether a contractor, painter, home builder or some other professional took the right action for a given circumstance. Without having intimate knowledge of a situation, it would be difficult to determine.
      We’re home improvement experts and prefer to stick to how-to’s and practical advice for enhancing a home. 🙂
      Good luck with the situation.

  34. Hello! Thanks so much for your wonderful advise.
    Our roof deck was recently replaced and now there is only the roof membrane. I would like to install interlocking rubber tiles. I have been reading that polyethylene uncoupling underlayment can be used over the roof membrane before laying the tile. Is this correct?? Is there a better material to protect the roof membrane? Please let me know. Thanks so much!

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