Hey, guys! Today’s video is about DITRA installation.
This past week, we got two separate questions from Nelson and Barrett. They’re Bathroom
Repair Tutor members, and they’re using DITRA in their bathroom remodel.
So this is DITRA. It’s got these cut back cavities on the top of it, and then this is
the back; this is the fleece side. This gets embedded in thinset mortar that is sitting
on top of either a concrete subfloor or a wood subfloor.
So why would you want to use DITRA between your tile floor and the subfloor? Well, DITRA
absorbs the movement of your home and prevents your tile from cracking over time.
So Barrett’s question was “Why should you use DITRA instead of cement board?”
Well, DITRA is only about an eighth of an inch thick, so it’s not going to add a lot
of height to your finish floor, and that’s great. The other thing is it’s also very
light to use. So this is just a little section that I cut out. And you can make your floor
completely waterproof using this and KERDI-BAND, which I’ll get into in a second.
So Nelson’s question had to do with, “Okay, I’m going to use DITRA, but how do I set
it on top of my subfloor?” Easy. So if you’ve got a wood subfloor, you want to use modified
thinset. If you’re not sure if your thinset is modified, you can look for Mapei Kerabond
and use Keralastic with it—that’s an additive. Or you can use Ardex’s X 5, which is a phenomenal
option. Or if you’re using Ardex X 77, you can use that too, but that’s a bit more
expensive than Ardex X 5. Now if you’re using DITRA over top a concrete
subfloor, you want to use unmodified thinset to embed it on the concrete subfloor. So,
modified for a wood subfloor; unmodified thinset for a concrete subfloor.
Schluter’s All-Set is also a great thinset option for setting DITRA on wood or concrete
subfloor. So before you add thinset to the subfloor,
we always recommend sponging it down with a damp sponge to remove any dust and debris.
And also, that helps prevent the subfloor from absorbing all the moisture from the thinset
mortar. Also, use an approved trowel to trowel out the thinset on the subfloor. This is a
DITRA trowel. But in the DITRA installation handbook, they also recommend different sizes.
So, this is super important. Comb thinset onto the subfloor using the trowel,
and keep all the notches facing one direction. This is called directional troweling.
Once your thinset is on the subfloor, you can roll out your DITRA fleece side down on
top of it. Then you can embed the DITRA using a grout float.
So how do you waterproof your entire floor using DITRA? Well, it’s pretty straightforward.
You use KERDI-BAND over top of all the seams. You want the KERDI-BAND to be evenly spaced
over the seam, and you embed it into the DITRA using unmodified thinset. You do the exact
same thing where the DITRA meets drywall. Now, here’s a big tip. You want to leave
¼” gap between your DITRA and your drywall, and your DITRA and either a shower pan or
your bathtub. You need that ¼” gap for expansion and contraction.
So the other question we got about DITRA is “How do you waterproof it when it meets
up with a shower pan or a bathtub?” The best thing that you can do is apply a bead
of KERDI-FIX to that ¼” gap and then embed your KERDI-BAND into that KERDI-FIX and the
DITRA itself using that unmodified thinset. That will waterproof that transition point
and ensure the water doesn’t get below the shower pan or below the bathtub.
I almost forgot to answer this question, and that is: “Can you use modified thinset to
fill in the cut back cavities on top of the DITRA?” And the answer to that is yes, you
can, but you have to let the modified thinset set up and be completely dry before you put
your tile on top of DITRA. Otherwise, if you’re going to install your DITRA and you want to
tile the same day, which you can do, you need to fill in the cut back cavities using unmodified
thinset. If you want to see how to install DITRA step-by-step,
click here; it’ll take you over to our site where you can watch our tutorial; it’s awesome.
And if you’re tiling your bathroom floor, we’ve got a great video on how to do that
as well. Thanks for watching today’s video. We appreciate
it, and we’ll see you in the next one. Take care.