Tiling Over Concrete Subfloor (with Ditra Uncoupling Membrane)

I have bruises on my knees.

No, that’s not my way of introducing a fourth occupation in my busy schedule (I may be crazy enough to work the equivalent of several full-time jobs at once, but turning tricks is not one of them).  The bruises are from here:

tiling over subfloor with Ditra

If it weren’t so far away, I’d have kneepads on my Christmas wishlist at this point.  But no matter, the hard part (if you can even call it that, it was actually pretty easy!) is done.  Follow me on my epically long thought process to explain why I’m beginning this project now:

I’m still in the middle of my kitchen renovation, but my parents have offered to supply me with a new washer and dryer as a graduation present.  They’ve given me a budget of less than $1,000 for the set, and I can’t help but think I can get even more bang (hehe) for the buck if we make our purchase on Black Friday.  And since that’s less than two weeks away, and I have no flooring in there thanks to Charlie’s puppy phase (gnawing on the baseboards too), and I hate the idea of moving the new appliances back out on my own just to tile the floor…

I’m doing it now, so I don’t have to later.  Project justified.  Maybe.

But that’s what brings us to this bright orange stuff.  It’s called Ditra, and it’s specially designed to handle a number of challenges that come with tile flooring.  It came highly recommended, and the reviews I’ve read for this stuff couldn’t sing its praises enough.  I don’t think I quite fully understand how it works, but after a minute or two, it starts to make sense.  When the seasons change, subfloors are impacted by temperature, vapors, movement, and moisture.  Tiny amounts of movement can cause issues for anything glued to it, like tile.   Too much stress on the tile (either from movement or an uneven balance of pressure), and before you know it, your beautiful tile job is a cracked, haggard mess.

Ditra is essentially a molded plastic sheet with fleece backing.  Its primary function is to help neutralize stresses in movement between the substrate (in my case, the subfloor, but it can also work with OSB or plywood) and the tile.  The fact that the tile isn’t bonded directly to the floor (aka uncoupled) keeps the movement of what’s underneath from cracking the tile stuck on top.

It’s not exactly cheap (and this isn’t a sponsored post), but installation is pretty easy (cost me $80 for a 54 sq ft roll, and I had to cover 45 sq ft).  You just need a utility knife to cut things to size.

tiling over subfloor with Ditra

Dad came over to help install, and we came up with a game plan to make it as easy as possible.  My laundry room is an odd shape, with one large square for the washer and dryer followed by a narrow hallway in front of the door.  We chose to cut three pieces, two fitting horizontally in the square, and one perpendicular for the hallway.  Doing this prevented me from having to spend extra time cutting a perfect notch in the Ditra to fit the corner (the image below shows ya what I mean).

Laying Ditra

To adhere the Ditra to the floor, you just need to mix a little tile mortar to the right consistency (like a thick milkshake – fluid, but able to hold shape).  The rain wasn’t exactly a helping hand during this project, but it did help to make sure none of the excess powder mortar stuck to my front porch slab.

mixing tile mortar

Note: it’s very important to use the right mortar for the job; it can’t be mixed with polymers and absolutely no premixed.  I had to ask the sales clerk at the store to help me find the right bag, but I was able to get all my materials in one big box store, so I was happy not to spend hours tracking down supplies.

mixing tile mortar

Spread tile mortar in sections, notch it with a trowel (size 1/4″ x 3/16″, using a 45-degree angle), and lay the Ditra on top, fleece side down.  (FYI: I’m wearing a mask and gloves as protection from the powder mortar.  Not only do I not want to be breathing the stuff in as a fine powder, but when mixed with water, mortar is corrosive on the skin.  Doing these projects so often now, I have learned to take better precautions.)

tiling over subfloor with Ditra

Use a grout float to put pressure on top, smoothing out any air bubbles to the corners.  It ain’t easy on the knees, but it took a couple of hours to mix, spread, flatten, and do it all over again for the next piece.  The room was too small for both of us to work in there together, so Dad mixed the rest of the mortar while I did the installation.  The hardest part was around the door, since I wasn’t smart enough to think about removing the door before we tried to install the last piece, and the door swings into the room.

tiling over subfloor with Ditra

But eventually, the entire room had a waffley orange coating.  The best part about using Ditra is that you don’t have to wait for it to cure before tiling, but Dad and I were already wiped and chose to tackle that part another day.  Instead, I just used a box of the tile to start dry fitting.

tiling over subfloor with Ditra

If you’re curious, it’s gray 12 x 12 ceramic tile that I found for 99 cents per sq ft while picking up the Ditra.  Very simple, and will let the rest of the room look clean and organized.  Again, because of the room’s odd shape, we’re having to do a little more planning to make sure that the tiles aren’t going to look odd along the doorway.  I think I have the layout I want, so the next step will be actual tiling.  Yay for easy install jobs, right?

tiling over subfloor with Ditra

What did your weekend look like?

Comments

  1. says

    Way to go. Doing this project now makes total sense! Have to get the deal on the w/d and can’t pull all that back out. Besides, how long would it take to get back to that job once the w/d are put in, right? I can’t believe Charlie!!! He is a mad chewing dog! I hope you have a way to get him away from your redone work–more chew toys? Wondering if you were going to add any panels or beadboard to the walls? May not be your style. And take more time. The wall behind the w/d looks messed but are the rest of the walls good and smooth? So excited for your graduation! I still see no place to send gifts on your post :)

    • Sarah says

      Yeah, that back wall is going to need a little work for sure :) I’m hoping to take care of the rest of it tonight & get it nice and smooth (a chunk of the wall sort of came out when removing the baseboards, which is just how things go sometimes).

      • says

        Yeah, funny story…I saved the proper way to remove baseboards from Sandra’s blog for my husband. We are doing a board and batten in the entry and upstairs hall of our tri-level. So he watched Sandra’s video and got started. He says to me about halfway through “I don’t think Sandra took into consideration our walls when she made the video.” Yeah, my husband was having a bear of a time, sweating, grunting, and a few small chunks came off with it.

        • Sarah says

          My laundry room just seems to be a bit of a bear to remodel. Between Charlie’s chew marks, poorly repaired water damage from WAY before I owned the house, and general creepiness of working in a small room that’s next to the garage, I’ve got my work cut out for me. But I have a game plan. Just gotta get that tile in first!

  2. Tina says

    If you do a job like this again, get yourself some knee pads, they are a life saver. If you are worried about scratching (some of them have hard plastic on the outside) you can always buy a pair of volleyball kneepads at a sports store.

  3. Janet says

    Very interested in this post! Am considering new tile in my kitchen and never heard of Ditra, I’m intrigued! BTW, if you have any of those plastic furniture moving discs, they make great knee pads and slide too! I just removed 7 billion (approximate #) carpet staples and tack strips and they worked better than the actual knee pads!

    • Sarah says

      Now THAT’s creative! I don’t have any of those, but I have a feeling this won’t be my last tiling project ever… might as well get some decent kneepads and get the proper gear.

  4. says

    Interesting. So in a sense the tiles float on the floor. I like the color you picked out and I think your house is going to be a showplace when it’s all done. I’m also beginning to think you’re a mad woman. But then again all of us that rehab or build our homes have to have a bit of craziness in us. Or we just get that way…

  5. Basement Waterproofing says

    This is a perfect example of how to tile a floor typically in the basement since it is concrete. We would highly recommend making sure your basement has no water or moisture in it before putting down tile because if there is, the tile will liking pop up and the moisture will soak thru the grout.

    • Sarah says

      If you’re going to be doing it for waterproofing purposes, be sure to buy the waterproofing tape for the seams (I wasn’t trying to waterproof mine, but it should be available in the same aisle and the same bright orange color where you find the Ditra).

  6. says

    Great job! It’s gonna look awesome when you’re done.

    We used Ditra in our guest bathroom and also added a layer of kerdi at the seams to make it completely waterproof (in the event there’s ever a large leak the bathroom becomes a small pan that holds the water). However, we put it down over OSB subfloor and used a very slightly modified thinset both above and below the ditra. The slightly modified is good for the OSB install (since it permits the air necessary for it to dry), but invalidates the warranty if you do it between the ditra and tile. However, we used a stone tile (which is porous) and gave it 14 days cure time before grouting. This is what a lot of pros that use Schluter products do, and they warranty the work themselves. The main thing here is that you can use the modified thinset as long as it’s not heavily modified. Personally, I like the Versabond brand thinset. It’s available at the orange big box and is easy to work with. Best of all, it’s very slightly modified and doesn’t cause a problem with Ditra.

    We’re going to use a small 1″ tile in our master bath so we can’t use the Ditra, since the minimum tile size it’s mean for is 2″ square. The gaps in the waffle can allow small format tiles to crack when someone puts weight on a small area. We’ll have to use a different membrane.

  7. Eileen Hill @ Precast construction Insualtion says

    hmmm.. you really give me an idea on how to remake our subfloor in our house, I’m gonna share this to my husband.. Thanks much for the great tips, it helps a lot!

  8. Jason Collett says

    I would have to use knee pads for sure but that does look simple enough to do. How did you decide where to start the tiles? Cant wait to see it all done.

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