Introduction: Install DITRA on a Wood Subfloor (stop Cracked Tiles)

By Home Repair Tutor
About: We love home improvement and enjoy sharing tips on YouTube and Home Repair Tutor. Everything we do is self taught. Over the last 12 years we've bought and rehabbed several rental homes in Pittsburgh. Sometim…

Cracked floor tiles stink…REALLY BAD

There’s a simple solution: DITRA

It goes down on top of wood or concrete subfloors.

Your tile then goes on the DITRA.

Today we’ll show you how to install DITRA on a wood subfloor.

PLUS you get to see a pro tile installer do it.

This tutorials is gonna make your tile installation way faster!!

Step 1: Gather Materials

Tile floors…there’s no doubt they make homes look nicer.

But what’s not so awesome are broken tiles.

This is a HUGE issue if your home settles over time.

Guess what, all homes settle!!!!!!!

DITRA solves this problem?

The best part is anyone can install it.

DITRA is way easier to install than cement board.

First, it’s light. Second, it stops tile and grout from cracking. Third, it can waterproof the wood subfloor.

If you’re afraid of mold in the bathroom DITRA will help. Steve and I will show you how to install DITRA today and make it 100% waterproof. Here are the supplies you need

  • Schluter DITRA
  • Schluter DITRA Trowel
  • Schluter KERDI-BAND
  • Schluter KERDI Trowel
  • Utility Knife
  • Modified Thin-set (Ardex and Mapei make great thin-set)
  • Unmodified Thin-set
  • KERDI-FIX
  • Caulking Gun
  • 1/2″ Drill (for mixing thin-set)
  • QEP Super Grout Mixer (for mixing thin-set)
  • Rubber Grout Float
  • Five Gallon Bucket
  • Nitrile Gloves

Step 2: Know Joist Spacing

Know the joist spacing of your home before installing DITRA.

Here’s the basic rundown of how to use DITRA for ceramic or porcelain tile:

  • 16 inch on-center joist spacing with single layer OSB or plywood subfloor
  • 19.2 inch on-center joist spacing with single layer OSB or plywood subfloors
  • 24 inch on-center joist spacing with double layer OSB or plywood subfloors
  • 24 inch on-center joist spacing with single layer OSB or plywood subfloors

Each configuration has specific guidance for:

  • subfloor requirements
  • substrate preparation
  • movement joints
  • thin-set, grout, and more.

Basically you can install DITRA over

  • plywood
  • existing vinyl floors
  • structural plank subfloors
  • concrete and heated floors.

BUT again, this tutorial is just for wood subfloors.

All the specifics for DITRA installation are in the handbook or on Schluter’s site.

IN GENERAL: ensure subfloor panels are level and properly fastened to the joists.

Inspect the floor for protruding nails or screws (fix squeaks before installing any flooring).

Step 3: Mix Modified Thin-Set

Once your subfloor is good to go it’s time to install the DITRA.

Mix up modified thin-set.

Thin-set should be mixed to a fairly fluid consistency.

BUT should still hold a notch.

How do you know you have the right modified thin-set?

Look on the bag for ANSI A118.1.

Again, modified thin-set is what you want between DITRA and the wood subfloor.

Step 4: Measure Floor Dimensions and Cut DITRA

Measure the floor dimensions and cut your DITRA.

You can cut DITRA with a utility knife.

Step 5: Dry Fit DITRA

Dry fit the DITRA on your wood subfloor.

Step 6: Clean & Dampen Wood Subfloor

Clean and dampen the wood subfloor.

This creates a solid bond between the thin-set and DITRA.

Step 7: Apply Modified Thin-Set

What trowel should you use to apply thin-set to the wood subfloor?

Check it out, we’ve got you covered

  • 1/4″ x 3/16″ V-notched or
  • 5/16″ x 5/16″ V-notched trowel or
  • DITRA trowel which features a 11/64″ x 11/64″ square-notched design

How’s that for detail!!

Apply the modified thin-set to the wood subfloor.

Notches should all run in the same direction.

Step 8: Embed DITRA Into Thin-Set

Embed the fleece side of the DITRA in the thin-set.

Leave a 1/4″ gap between walls and the bathtub.

Use a rubber grout float to push the DITRA into the thin-set

Step 9: Check Thin-Set Coverage

Lift up a corner of the DITRA to check for thin-set coverage.

Your goal should be 100% coverage…we had a few bare spots here and fixed that issue!!

Step 10: Abut End and Side Sections

You can abut end and side sections of adjacent DITRA sheets.

Step 11: Watch the Video Tutorial (Part 1)

Watch our step-by-step video for all the juicy details

The beginning shows you why I like DITRA versus cement board

This is Part 1 and shares the entire step-by-step of installing DITRA on a wood subfloor.

Step 12: Start the Waterproofing...

So how easy is it to waterproof DITRA?

Pretty darn simple.

At the joints, fill the cavities with unmodified thin-set mortar.

Make about an 8 inch band of thin-set centered over DITRA joints.

Step 13: Center KERDI-BAND Over Joints

Comb additional thin-set over the joint using an approved trowel.

Center the 5 inch wide KERDI-BAND over the joint.

Step 14: Firmly Press KERDI-BAND Into Thin-Set

With the flat side of the trowel, firmly press the KERDI-BAND into the mortar.

Make sure to fully embed the KERDI-BAND and remove any excess mortar and air pockets.

You can use this same method where DITRA meets drywall.

We used a 5 inch wide KERDI-BAND because if it’s centered, your base molding will hide it.

Check out the video for those details.

Step 15: Fill Gap Between Tub and DITRA

One of the worst spots for water damage is where your tub meets the tile floor.

Fill the 1/4 inch gap between the DITRA and tub with KERDI-FIX.

Step 16: Embed KERDI-BAND

Fill in the cavities with unmodified thin-set and embed the 5 inch wide KERDI-BAND

Step 17: Watch the Part 2 Video on DITRA Waterproofing

Steve shows you the exact method in our video,

you’ll be a whiz at DITRA installation after today!

DITRA is the easiest way to waterproof your floor and prevent tile & grout from cracking.


What do you think, do you feel like you could install DITRA?

Let me know in the comments.

ALSO: if you have a question, fire away in the comments.

As you can tell…I’d love to hear from you, haha.

Thanks for reading, watching and being an awesome DIYer.

Jeff

Founder, Home Repair Tutor