Install Schluter Ditra over plywood

This post is all about the installation of an uncoupling membrane (Schluter Ditra) over a plywood sub floor. If you would like to learn some more about prep work for a wooden subfloor, check out my full YouTube Video on how to prep a wooden subfloor for tile.

Links to Products Mentioned:

Schluter Ditra: https://amzn.to/3PGwop4

Schluter All set: https://amzn.to/3zcOBDM

Ditra Trowel: https://amzn.to/3S8X6bq

Floor Roller: https://amzn.to/3vlRwZr

Knee Pads: https://amzn.to/3zFjiD4

Sponges: https://amzn.to/3PK8GIG

wooden float: https://amzn.to/3S6fLon

Benefits of an uncoupling membrane under tile:

Schluter Ditra Uncoupling Membrane

If you are new to tile installation or the home improvement world, you may be unsure of the purpose of an uncoupling membrane. What does an uncoupling membrane do? It prevents any movement of the subfloor below affecting what is being installed above it. This helps mitigate any cracks or damage to your tile floors down the line. Here is how you install Schluter Ditra uncoupling membrane over plywood.

How to install:

STEP 1: PREP THE SURFACE ( IMPORTANT)

When you are doing a remodel and demo an existing floor, whether it be tile or some other type of floor, a common mistake I see is the wooden & concrete subfloor not being prepped properly. If there is dirt, dust, or debris on your subfloor, you are compromising the install of any tile application. Your tile install will only be as strong as what its bonded to, so if there is paint overspray, drywall and dust all over your wooden subfloor, your tile will not properly adhere. All of these things are bond breakers for thin set so it wouldn’t matter if you were using an uncoupling membrane or not.

Full tutorials below on how to prep a wooden subfloor and a concrete subfloor:

For a full tutorial on a how to prep a wooden subfloor for tile watch my YouTube video: HERE

For a full tutorial on a how to prep a concrete subfloor for tile watch my YouTube video: HERE

STEP 2: Dry lay your pieces

I would recommend cutting the pieces of your uncoupling membrane before starting the installation to create a better flow once you mix your thin set. You can cut the Schluter Ditra with a scissor or a box knife.

**We do this perpetration step to ensure timely install once the thin set is mixed. You do not want to have your thin set get too dry, it will compromise the install.

After I measure and cut the pieces of the membrane, I like to dry fit them by laying them out and use a pencil to mark where each piece ends and begins. This will save you down the line from applying thin set in a larger area than you need for each piece of the membrane. If you apply thin set past the section you are working with, it may begin to dry before you are able to apply the next section of the uncoupling membrane. I also cut out any sections like around door jams and toilet flanges while dry fitting.

Pre- cut and mark each piece before mixing thin set

After your pieces of membrane have been cut, it is time to mix up your thinset.

STEP3: Mix the thin set

Schluter All-set thin set

For this specific project, I used the Schluter Ditra Uncoupling Membrane. I am using the thin set

that is recommend by the manufacturer for the uncoupling membrane. Always check with your products’ manufacturer instructions when selecting a thin set to use with the uncoupling membrane to ensure the best installation.

The thin set instruction state it should be mixed on the looser side when installing the uncoupling membrane, but once again make sure to check the specific product that you use for the instructions that you should follow.

STEP 4: Wet section with damp sponge

Wet the section prior to applying thin set

***In this example, I poured self-leveler over the plywood to get the floor flat prior to the install that’s why the floor looks like cement. If you need to pour self-leveler over plywood, watch my full YouTube tutorial: HERE.

Now that our thin set is prepared, I like to use a sponge to lightly wet the floor before applying the thin set. This allows the floor to suck up the water instead of absorbing all the moisture from the thin set when you begin to apply it.

Step 5: Installing the membrane

The next step in the process is start installing. To start you want to “burn” in the thin set. Burning in the thin set means using the flat side of the trowel to apply a thin layer of the thin set before applying the layer with the notches. Here I am using the Ditra Trowel.

Apply thin set with the Ditra Trowel

Above, you can see me using the flat side of the trowel (the side without any ridges) to essentially scrape a very thin later of the thin set over the area. After this is complete, you then go back over the area and apply more thin set the notch side of the same trowel. Make sure you are using the specified trowel size from the uncoupling membrane data sheet found on the Schluter website. Each uncoupling membrane on the market is similar but different and it is always good practice to review instructions prior to installation.

Adding more thin set with the notch side of the trowel

Apply membrane over thin set in small sections

Remember, after you key or burn in the thin set with the flat side of the trowel, you will need to add more thin set to add the notches with the notched side.

After you have the thin set applied in the section for the piece of membrane you are working on you can lay the membrane down on top of the thin set.

Using a floor roller, collapse the ridges to get full coverage and get out any air that may be trapped

Next, use the floor roller by rolling opposite the notch direction to make sure to get out any air bubbles and collapsing all the ridges. The goal is to get full coverage under the membrane and make sure you get a complete bond to the substrate.

Its okay if you see some thin set oozing out from the seams and edges. You can clean that up later.

Wooden Concrete Float

If you do not have a roller, a wooden float will also work but may be harder to use as you will need to apply significant more pressure to get the same job done as a floor roller. I have used both methods with success.

Thank You

After you finish rolling the uncoupling membrane with the floor roller or flattening with the concrete float, use your wet sponge to wipe away any extra thin set that may have been pushed out during the rolling process.

Once all the extra thin set has been wiped away from the joints, you can waterproof the membrane by applying Kerdi Banding to the seams. This is an optional step for certain situations.

If you would like to follow along to the video where I apply uncoupling membrane to a wooden subfloor, check it out here.

Thanks for reading<3

This post may contain affiliate links, which means I'll receive a commission if you purchase through my link, at no extra cost to you.