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Schluter Kerdi Board Installation Tips for Bathtubs — by Home Repair Tutor


This video is going to share Schluter KERDI-BOARD
installation tips. And the reason why is: number one, it’s
super light. It weighs just a few pounds. When you cut it, there’s no dust, and you
can waterproof a tub shower or shower surround in one day. So it’s a very quick and straightforward
installation, yet we continue to get questions about this. So we’re going to answer those questions
in today’s video, and we’re going to give you those installation tips. Two things before we start: this is not a
Schluter-sponsored video. We legitimately get a lot of KERDI-BOARD questions
via email and on our different platforms. Secondly, we wanted to give you a Bathroom
Repair Tutor update. Bathroom Repair Tutor is our online course
that provides detailed step-by-step video tutorials for folks who want to do DIY bathroom
remodels or for people who want to get into bathroom remodeling as a business. So we now have over 190 different tutorials
that show you step-by-step how to build custom bathrooms and tile showers. So if you’re interested in that, check it
out down in the description. We’ll put a link to Bathroom Repair Tutor
down in the description, and we definitely think it could help you out. KERDI-BOARD is a foam board. There’s a fleece on both sides. So this is the finish side that you should
have facing out toward you. And on the back is the same fleece, but it
doesn’t have any lines on it. Between the two fleece layers is foam. This foam has an R value of 2.2 for half-inch
KERDI-BOARD, which makes it a great option on outside walls. The foam is also what makes it super light
and easy to cut. Obviously, there’s no dust with foam. KERDI-BOARD can be installed over wood or
metal studs; either one is fine. And you use Schluter screws and washers with
a drill or impact driver to do the installation. Schluter ALL-SET or unmodified thinset is
then applied over the seams and screws, and then KERDI-BAND applied over top of that to
waterproof all the penetrations. The great thing about KERDI-BOARD is you can
set tile on the same day that it’s installed. We always get asked about the supplies needed
for this kind of project, so it’s: KERDI-BOARD, KERDI-BAND, KERDI-FIX, ALL-SET Mortar or unmodified
thinset, screws and washers from Schluter, the KERDI Trowel, utility knife, level, and
drill. It’s super important to check all the studs
and make sure they’re even with each other. So get yourself a 4-foot level or a 6-foot
level and check that. They also need to be 16 inches on center. So that’s per the Schluter recommendations. The plumbness of all the studs should be checked
as well. Because if there’s any deflection or irregularities
in the studs, the board will flex. But that goes with cement board and pretty
much any other foam board too. We always set our bathtubs level. But if you didn’t set the bathtub and somebody
else did, just make sure that it is in fact level. Because if it’s not, this will affect the
draining and the tile work. The other thing that we like about KERDI-BOARD
is the fact that it has lines on the surface, and this makes cutting it super easy with
a utility knife. Here in Pittsburgh, we often encounter really
weird walls and wonky shower situations. So using something like KERDI-BOARD helps
out a lot because you just fine-tune the cuts with a utility knife, and you can get pretty
much any shape you want. And if you have a knee wall or a bench, you
can use KERDI-BOARD over top of that. The screws just need to be 16 inches on center
horizontally and 12 inches on center vertically along studs. The screws should also be depressed slightly
below the KERDI-BOARD. The next step after installing KERDI-BOARD
is filling the seams and the screws using unmodified thinset. In this case, we used MAPEI’s Kerabond. You can also use Schluter’s ALL-SET, which
is great. And then we applied KERDI-BAND over top of
that and smoothed it out with a drywall knife. Now, we also go over top of the KERDI-BAND
with a sponge so that the excess thinset doesn’t interfere with our tile work. All the screws were filled in with thinset
as well. And then one trick we like doing is we hold
one side of the KERDI-BAND with our KERDI trowel and we smoothed out the other side
with our drywall knife. And then we sponge over top of that to get
a smooth finish. This was a Cape Cod bathroom, and the KERDI-BAND
kinked in the corner. So we cut it, back-filled it with the MAPEI
Kerabond, and then just created a patch using an excess piece of the KERDI-BAND. The KERDI-BAND just has to overlap by 2 inches. Then we held the KERDI-BAND in place with
the KERDI trowel and smoothed it out with our drywall knife. One question that comes up a lot is, “What
do you do between the KERDI-BOARD transition and drywall?” In this case, we applied our thinset over
top of that transition. Again, equidistant on the other side of the
transition. And then we troweled it with the KERDI trowel
and applied our KERDI-BAND over top of that and smoothed it out with our joint compound
knife. And then also sponged it down quite a bit
because either you can use joint compound to smooth that transition or you can, better
yet, tile over top of it. Schluter makes these great mixing valve seals. We don’t use them all the time, but if it’s
a circular mixing valve, we do. And there’s a thicker side of it that goes
into the wall. So you have to cut out a circle out of your
KERDI-BOARD and then dry-fit this before you actually bond it to the KERDI-BOARD. So we always recommend doing that—dry-fitting. And then we add our thinset. We trowel it in. We comb it in using the KERDI trowel. And then we add our mixing valve seal. Now, we’ll hold one end of the seal with
our KERDI trowel, and then we’ll smooth it out with our drywall knife. And then we take our sponge and smooth that
down as well. Connecting KERDI-BOARD to the tub begins with
taping off the tub and using KERDIFIX. We cut the tube to a big size, and then we
back-filled the gap between the KERDI-BOARD and the tub. So we’re basically just going over top of
the tub flange that’s connected to our studs. We’re also going along the side of the tub. And in this case, where the casing was going
to go because it’s very, very small bathroom. Then we used a 3-inch putty knife to smooth
out the KERDI-FIX and wiped any excess off on a scrap piece of KERDI-BOARD. And we also smoothed out that area for our
tile. You can also back-fill any pipes with the
KERDI-FIX. We immediately applied our MAPEI Kerabond
over top of the KERDI-BOARD section. You only have to go up about 3 inches and
then comb it in with the KERDI trowel. And then add KERDI-BAND over top of both the
thinset and the KERDI-FIX. You can cut a little slice of into the KERDI-BAND
to go over top of the tub spout that’s coming out of the KERDI-BAND. Smooth everything out using your drywall knife
or KERDI trowel, and then remove your tape for a smooth finish. So definitely have a smooth finish at this
area because you don’t want that to interfere with your tile. Another option for connecting the KERDI-BOARD
to the tub is to draw a line on the bottom back of the KERDI-BOARD and cut a rabbet into
it using a utility knife. So basically, a rabbet joint is like a little
L-joint, right? So you need to cut both on the back and on
the foam portion that is exposed on the bottom of the board. Because basically what this rabbet is going
to do is overhang the bathtub flange. So you just need to cut along the line that
you drew and then peel back both the foam and the fleece because what that will do is
overhang the tub flange and then you can still apply a little bit of KERDI-FIX in that gap
to seal it to the tub. This will save you a tremendous amount of
money and a tremendous amount of KERDI-FIX. Give us a thumbs up if you like the tips in
this video. And keep in mind, we have several video tutorials
that show you how to install Schluter KERDI-BOARD, so those might come in handy for your project. Thanks for watching today’s video, and we’ll
see you in the next one. Take care!

Bernard Jenkins

10 Comments

  1. Awesome tutorial very informative yet to the point! Looking forward to using the kerdi system on our next bathroom reno projects. Thank you! 💎

  2. it is great to work with being so light, but at $100 per 8ft X4ft board + special screws +special washers+ kerdi band+ kerdi fix+ thinset to apply it is a hard sell. Cement backerboard and liquid waterproofing will save you a ton of money. I do bathroom remodels for a living, I use both, I just wished schluter was a bit more price competitive

  3. Schluter's Kerdi-Board is very user friendly and convenient, plus tile can be set over it on the same day as installation. Tips in this video hopefully clarify questions about the system. More systems and tiling videos are available inside Bathroom Repair Tutor which now has over 190 detailed video tutorials https://bathroomrepairtutor.com/

  4. The grid on the Kerdi board and the Kerdi membrane really comes in handy when cutting and installing tile. Great video.

  5. Which foam board board do you use most of the time? Wedi, Hydroban, or Kerdi

  6. Great tutorial. Wouldn't the foam board be weaker than a cement board? It seems that if someone fell or pushed against the wall the foam board would cave in or break. I'm sure the tile will give it some rigidity but it seems like cement board with something like RedGard, HYDRO BAN, etc, to waterproof it would be stronger.

  7. Super useful vid. I think everyone was confused if the board should overlap the tub flange or butt on top of it. The rabbit cut is a best of both worlds solution

  8. Seriously, where do you buy this stuff now? HD, Lowes dont carry it. They only seem to sell full shower kit which I (and I am sure many other buyers) dont really need. The website listed vendors in DC area seem to be remodeling vendors and not resellers of the product.

  9. Great tutorial!!! Question! What do you do if you install the kerdi band wrong and the thinset hardened already?

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