How to Waterproof Bathtub Walls (3 Awesome Methods)

How to Waterproof Bathtub Walls (3 Awesome Methods)


All right. So in this video we’re going
to give you three awesome methods for waterproofing your bathtub surround. We constantly get asked,
“What do you think is the best backer board for bathtubs?” So in this video we’re
going to go over KERDI-Board, HYDRO BAN Board, and Wedi. We really think that those are the
three best options for waterproofing a bathtub surround. I’m not going to be asking, “What
about cement board?” Well cement board is always an option. But the problem is it’s
heavy, it creates dust, and you got to waterproof it. So cement board is water resistant, but
you got waterproof it with something like RedGard or a liquid waterproofing membrane.
So we’re going to dive in to the three different methods. We’re going to give you tips on
how to install each board. And at the end—so make sure you watch the video until the end—we’re
going to give a final assessment. This bathtub installation began by us furring
out the main wall. So we simply tacked or nailed ¼” plywood to that. Then we cut
our HYDRO BAN Board to size and just dryfit it. Now the main thing with HYDRO BAN Board
is you have to apply their adhesive/sealant to the tub flange or to the tub deck. So we
use 1-5/8” HYDRO BAN Board screws; you need to get those. And we cut this board to size
using the oscillating multi-tool from Fein. What’s nice is you can also simply use a
utility knife. So it’s really easy to install the HYDRO BAN Board.
Now, the other cool thing is, adhere this to the studs and you can also make a custom
shower niche. So in this case, the niche needs to be pitched downwards ever so slightly.
And we used the HYDRO BAN sealant on the back edge to do that, to accomplish that. So it’s
¼” per linear foot. Then we cut the rest of the board to size using the MultiMaster.
And now what we’re going to do is add the HYDRO BAN Board to the back wall here.
Now because we have drywall on the other side, we’re simply going to be using the sealant.
This is not silicone. This is a special HYDRO BAN sealant adhesive for the board. And you
want to add that to all of the perimeter surface area of the boards that are going to be meeting
up with each other. Now in the corner here and along the tub flange,
we added more sealant because what we’re going to do is we’re going to run that board
on the plumbing wall, actually into the shower niche. And we’re just going to screw it
in place. You’ll notice we don’t need to use any type of washers for this; just
the screws. But you do need to add the sealant between boards.
The other thing that you need to know is that all the studs need to be 16” on center,
plumb, and even with each other for HYDRO BAN Board. That pretty much goes for any backer
board. Then we just used more sealant along the seams and in the corners and on the screws.
You can see this is a very fast installation because you just need the sealant. And I can’t
emphasize this enough: it’s not silicone. A lot of people confuse the sealant with silicone,
and it is not. But as you see here, we sealed all the seams and around this tub spout opening.
That’s what’s nice about this sealant. You can do that. You don’t necessarily need
anything extra for it. And you can do the same thing where the board is attached to
the flange. There’s a gap between the board and the tub deck. You need to fill that in
using the HYDRO BAN sealant/adhesive, but that’s very easy to do. And it creates a
100% waterproof seal. You can do the exact same thing between the boards and drywall.
You can add the sealant. Just make sure it’s flat.
This is our final look for that tub. The other board that we like is KERDI-BOARD.
This is easy to cut using a utility knife. The studs need to be 16” on center, even,
and flush with each other. The difference between HYDRO BAN Board and KERDI-BOARD is
that you do need screws and washers. Now, the nice thing is there are lines on the front
face of the KERDI-BOARD, and that’s really nice for cutting out holes for the rough-in
valve and the stub out for the tub—the tub spout.
It also is very easy to cut these boards to any shape and dimension. And we had to put
a little piece here up against the tub. We built a knee wall out of the KERDI-BOARD.
Very simple to do on all three sides of the knee wall. Again, you have to use screws and
washers. And we added tape to the tub deck, and we’re going to be using KERDI-FIX sealant
between the board and the tub deck—that’s why we added the tape to the tub. So that
gap is filled in with KERDI-FIX. And what that does is two things: number one, it waterproofs
the screws that are holding the tub in place; and also, it’s going to create a waterproof
seal between the board and the tub itself. So we’re simply filling in all these gaps
with KERDI-FIX. And the next thing that you need to do is to flatten that out. So we recommend
using a 3-inch putty knife to do that. If you don’t already have the thinset mixed
up, you need to start mixing up thinset at this point or before you even add the KERDI-FIX,
that’s preferable. You can also use KERDI-FIX to waterproof around
the tub spout, and we added Kerabond to the top most portion of the KERDI-BOARD. Now the
Kerabond has to be nice and loose, and you need to apply it using the KERDI trowel. We
also recommend having a sponge available. But we added Kerabond to the top 3 inches
of the board that is above the tub deck. So we actually used a 6-inch putty knife or drywall
knife here to apply it. And then we troweled more of the thinset on using the KERDI trowel,
and then used KERDI-BAND over top of both the KERDI-FIX and the Mapei Kerabond unmodified
thinset mortar. And we used one piece of the KERDI-BAND and then pulled our tape after
that. Then we added more Kerabond to all the seams.
All the seams need to be waterproofed using unmodified thinset and KERDI-BAND, or you
can use Schluter’s ALL-SET. But we highly recommend using an unmodified or ALL-SET and
nothing else. Here we’re just adding the mixing valve
seal and smoothing out the Mapei Kerabond using our knives and sponging it down. You
don’t want any thinset build up between the KERDI-BAND and the board if at all possible.
You want to smooth that out. And the biggest thing is mixing up the thinset to the right
consistency. If you get ALL-SET by Schluter, that will help out quite a bit because they
actually give you specific directions for doing this waterproofing.
Now between the drywall and the KERDI-BOARD, we actually applied thinset and KERDI-BAND.
We get this question all the time: “What do you do between those two substrates?”
Now you can waterproof the entire knee wall using just the Mapei Kerabond or ALL-SET and
the KERDI-BAND. So you want to add the KERDI-BAND to all the seams. You want the KERDI-BAND
to overlap by at least 2 inches on all sides. So this can actually create some build up.
As you can imagine, you’re adding a lot of pieces of KERDI-BAND to the top and the
sides of the knee wall. So that’s why the thinset consistency is super important. But
this isn’t terribly difficult. You just need to apply the thinset, trowel it out,
and add the KERDI-BAND over top of all the seams. It does help to have the KERDI-BAND
precut. So if you have time to precut it, that’s great. If you don’t, as long as
your thinset has a good pot life, then you shouldn’t have any issues applying the KERDI-BAND
to the top of the thinset layer. But that’s how we waterproof the entire knee wall in
this tub/shower combo. Again, it’s important to smooth out all the thinset. And then for
this outside corner, we applied more thinset to the three sides of the walls here. And
we just smooth out that outside corner so it was nice and flush with the KERDI-BOARD.
And then all the screws and seams have to be waterproofed using KERDI-BAND and thinset
as well. This Wedi installation began by adding ¼”
plywood to the back wall; I’ll explain here in a second. Then we applied Wedi joint sealant
to the tub deck. And by adding that ¼” plywood, we are able to drop the Wedi board
down over top of the tub lip and save some money on the Wedi joint sealant.
We measured all the studs out and added our screws and washers along the center of the
studs. All the screws and washers for every single board need to be at least 12 inches
along the center of the stud. That goes for KERDI-BOARD, HYDRO BAN Board, and Wedi. The
studs for all these need to be 16 inches on center as well.
Now, we’re just cutting out the area where the Wedi preformed shower niche is going to
go. And then we added Wedi joint sealant along the perimeter of that and installed the Wedi
preformed shower niche using the screws and washers.
We kept on going. We added Wedi joint sealant to the top of this board, cut that small section
to size, and then we just added the board on the plumbing wall and cut out the Wedi
board using a utility knife. Here, we’re just saying you got to make sure that the
depth of the shower valve is the right depth. We used the iBox. We added the Wedi joint
sealant to the back of that. Added the backer board to it. Screwed it in place. Added Wedi
joint sealant where the tub meets up with the board and where each Wedi board meets
up with each other. And then you just continue to do this on the bathtub surround. We’re
just cutting out some drywall to make sure that the Wedi can fit flush with the adjacent
walls. Adding joint sealant to each top of the board. And then screwing them in place.
This is a very fast installation as you can see because you’re just using the Wedi joint
sealant to seal all the boards to each other. Here we’re just using a dado cut to cut
out some of the Wedi and make it flush with the tub lip on the side of the bathtub itself.
Now here’s the deal, you need to fill in the gaps between the Wedi board and the tub
deck. You need to fill in all the seams using Wedi joint sealant and the screws and washers.
There’s a Wedi corner knife that really helps out with this. And you need to have
one inch of sealant on either side of the seams. Same thing goes with the screws and
washers. You got to fill in this gap using all that Wedi joint sealant. But again, just
like with KERDI-FIX and the HYDRO BAN adhesive sealant, it waterproofs the tub connection.
Now between all these plumbing connections, you can also use the Wedi joint sealant to
make a waterproof seal, and it really makes for a fast installation. Here we’re just
adding the joint sealant to the small seam on the back wall but filling in on the side
here. Now if you do have drywall, you can use the joint sealant between the drywall
and the Wedi boards. And here’s what our final bathtub looked
like. Here’s the million-dollar question: “Which
board should you use for your bathtub surround?” Well, it really breaks down to three things:
cost, distribution—can you get it?—and speed—how fast is it to install?
In terms of the cost, Wedi is the most expensive, followed most likely by KERDI-BOARD, then
Laticrete’s HYDRO BAN Board is the most cost-effective. In terms of distribution,
we find that Schluter’s probably the best, followed by Laticrete, and then Wedi is tied
for second there. In terms of the speed, HYDRO BAN Board is probably the fastest because
you don’t necessarily need washers, followed by Wedi, and then KERDI-BOARD is last—it
takes a bit longer to install. Now, the other X-factor that you should throw
into this is support. What kind of support can you get? Well, Schluter’s support is
the best in our opinion, followed by Laticrete, and Wedi is last. I’ve never been able to
get somebody on the phone from Wedi. It’s always been a challenge working with them.
But we really like their products, all things considered.
So let us know what your thoughts are down in the comments. What’s your opinion on
all three boards? And we’ll see you in the next video. Take care!

10 thoughts on “How to Waterproof Bathtub Walls (3 Awesome Methods)

  1. Boom, Shacka, Lacka, another video of mad Knowledge!!!! Thank you so much for all that you do for the industry!! Dirty Jersey out!!!

  2. I really want to use Wedi. I’m seeing the cost is pretty significant and hearing their support isn’t good. Tough call. I really think it’s a superior product

  3. Thank you so much for this video, this is precisely what I have been looking to learn. That said, it sounds like one is not necessarily better than another, but just that they all have their pros and cons. I agree that Schluter's support is excellent, and that goes a long ways. Does the fact that you used Mapei thinset void your Schluter warranty?

  4. I used Schluter products for my bathroom, I was really impressed with their products. They were all good quality and they have everything that you need. I had a crack in the fiberglass wall of my swimming pool so I sealed it with Kerdi fix, it worked perfect no leaks.

  5. The backer board goes right up against the top of the bath deck without any gap? There's no expansion due to heat, cold, etc?

  6. So… I am making a cement shower… then I thought, since I finished tiling my floors and have a lot of thinset left over, can I make my shower walls out of thinset instead? I will be sealing the cement walls with tung oil, and dan use the same for the thinset, but am wondering what things I should consider if I use thinset instead.

  7. Not really three different methods shown. Just three different insanely expensive products for the same method.

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