Hi, I’m Jeff Patterson, founder of Home
Repair Tutor. And I’m Sal DiBlasi, Elite-tile Company.
I’m from the Boston area. And I’m in Pittsburgh. So we figured even
though I’m a Steelers fan—I’m sure you’re a Patriots fan—we’ve come together to
make this great video on thinset. We’re going to divide the video up. I’m
going to be talking about some areas that I made, especially spot bonding. And Jeff
is going to talk about the proper methods of…
How to apply the thinset to the back of the tile, commonly known as backbuttering and
the pattern of the thinset that you want to see whenever you’re applying it to the wall
or a tile. One of the major problems when installing
tile is the actual application of the thinset and the troweling and just the coverage of
the thinset. So we felt that it was important to give some good information on what the
proper methods are and what the problems are. So these quick tips, hopefully they help you
with your own project when it comes to tile work, and they help you do the project the
right way. So we’re going to be jumping into the video. The first part of the video
is going to be Sal sharing his knowledge about what you should do, what you shouldn’t do
with the thinset. I’m going to go over one of the most common
areas, and Jeff is going to give us some information on the things you should actually do.
So, we’re going to jump into the video right now.
Thanks. Okay, so what we’re going to talk about
today is spot bonding, which is an improper way of installing tile on a surface, whether
it be a wall or a floor. Now what is spot bonding? Spot bonding is when you get a tile.
You mound globs of thinset on the back of the tile. Most of the time it’s like five
globs, but sometimes there will be six or nine. But it doesn’t really matter how many.
The point is that they put globs or mounds of thinset on the back of the tile. Then what
they’ll do is they’ll get that tile and push it into the surface, whether it be a
wall or floor. And the reason they do this is because it makes it easy for an installer
to get a flat, even surface and get very little lippage or eliminate lippage because they
can push the tile in and out a corner or whatever and get the tiles even. The problem with that
is that thinset is not designed to be used in globs.
What happens is you got the tile on your wall, let’s say, and you’ve got these mounds
and you push them into the substrate, and you got a nice, even surface. Now in the back
of the tile, you’ve got all kinds of voids. Very little of the tile is actually supported.
So you’ve got a lot of empty spaces behind the tile.
And the other issue with that also is that the thinset, as it dries, it’ll shrink,
pull away from the tile, and leave the tile with very little support and very little bond.
Now some guys will also spread a layer of thinset with their notch trowel on the surface
and then they put the mounds on the back of the tile, the spots, and then they push it
in, thinking that that way they’re going to get good coverage. Not true. Doesn’t
happen. There’s still going to be a lot of empty spaces.
Another reason to do this is because you can avoid doing the needed prep work. If you’ve
got a rough surface and it’s not well prepared, you can get a flat, even surface without doing
hardly any prep because you got these big globs of thinset behind the tile. So doing
it this way by the time you’re done, and you’ll probably going to have a nice, good-looking
tile job, even, etcetera, etcetera. But in short order, you’re going to get all kinds
of problems. Because the tile isn’t properly supported—I’m
just going to go over these details on how to spread your thinset, what kind of coverage
you’re supposed to have, etcetera, etcetera—because you don’t have the recommended coverage
and you don’t have the support that the tile needs, it’s subject to cracking very
easily, to become completely unbonded to the floor, the corners can crack, you can break
off all the voids behind the tile; it’s just a big, huge issue.
So if you’re in a dry area, you’ve already got huge problems. Now if you do that in a
wet area, you’ve got even more problems. Because, let’s say in a shower stall, you
got all these voids behind the tile. You got all these empty spaces. And the water in the
shower is going to penetrate behind the tile. And as it gets behind the tile, it’s going
to accumulate, and you’re going to get mold and mildew and who knows what else growing
behind that. So that’s another problem. And then the tile can also discolor, and depending
on the kind of tile, you get dark and light areas of tile, discoloration, all sorts of
things. Have you ever even seen mold especially on natural stone? Have you ever seen mold
grow inside the tile? The actual tile has mold growing in it.
So if you’re going to install tile, you need to use proper methods, proper procedures
so that you don’t run into these issues. Yeah, sometimes you can find a method that
is going to make it a little bit easier, that’s going to give you a good-looking job with
less effort. But by not getting the coverage that you need for the tile, for the thinset,
in short order, you’re going to have all sorts of problems.
These are just some of the problems that you can have. Jeff is going to go over the main
points that you need how to use thinset and what you need to achieve for proper calibration—that
kind of stuff. So I’m going to hand it off to Jeff, and he’s going to vie you some
good information that you really need to know. In this part of our video, we’re going to
be talking about thinset coverage and backbuttering. Is backbuttering absolutely necessary? It
is absolutely not. But it does provide you with extra insurance that your tile is going
to stick to the substrate. Many of the tips that you’re going to see
here in a second come from the TCNA handbook. If you’re not familiar with the Tile Council
of North America handbook, check it out. It’s a really great guide.
So for example, in the TCNA handbook, they recommend that 80% of the back of the tile
be backbuttered if the tile is going to be in a dry area. What do you do for a tile that’s
going to be in a wet area like a shower or a bathroom floor? Well the TCNA recommends
that 95% of the back of the tile be covered in thinset. We’re going to go over that
in a moment here. Also, you want the thinset to be evenly spread
on the back of the tile. You don’t want 20% to be right here, and the other 60% to
70% of it to be all over here. Just evenly spread the thinset on the back of the tile.
The other super important thing when thinking about thinset coverage is the size of your
notch in your trowel. So here is a KERDI trowel. It’s a 1/8” x 1/8” square notch trowel.
You would never use this to adhere or set tile to a wall or floor. It’s only good
for KERDI-Board. This, on the other hand, is a ¼” x 3/8” x ¼” square notch trowel.
And this is a really great option for certain tiles.
And by the way, if you’re looking for a recommendation on how to choose the correct
trowel size, click right here. There’s a video by Sal that’s phenomenal. You should
definitely check it out. All right, let’s do some testing.
This is just a standard 12” x 12” tile, and I’m going to turn it over. As you can
see, the back of this tile is not flat. If it were, you could technically use a smaller
trowel and still get good coverage on the back of the tile by backbuttering and by using
directional troweling on the wall or the floor. But as it stands, you can see this is not
flat, and you have a lot of voids in here, and there’s porosity to the tile. Because
of all the voids on the back of this tile, it is advantageous to backbutter it because
you’re going to fill in all these voids and the pores with the thinset. And this will
make it easier to achieve recommended coverage when the tile is placed on the comb thinset
that’s on the substrate. Okay, so let’s dive into our test. Test
number one is going to be using this Schluter-KERDI trowel. Totally undersized. Definitely not
meant for adhering tile to a substrate. This first test, we’re just going to spread the
thinset onto the substrate here, which is KERDI-Board reversed. So we’re just going
to trowel the thinset on one direction. Here’s our thinset. We have our directional troweling.
So all the ridges are going in one direction. We’re just going to put our tile on it and
push down firmly into the KERDI-Board. So I’m going to take this tile off and turn
it over for you. If this tile were white, it would be even
more apparent. But the coverage here is terrible. It’s not great. None of the thinset is in
the voids of the tile, and that’s not good. This tile would definitely come up off the
substrate over time. So this goes to show you that an undersized trowel is not good.
This next test, we’re going to be using a ¼” x 3/8” x ¼” square notch trowel.
And what I’m going to do is show you why directional troweling is super important.
Directional troweling is basically north, south, east, west—all the trowel ridges
are in the same direction. Sometimes when you see videos on YouTube, you’ll see somebody
do these swirl patterns. So no backbuttering of the tile here. We’re
just going to set it firmly into the KERDI-Board or whatever substrate you want to pretend
this is. And we’re going to move it back and forth, too. All right, let’s go ahead
and pick up this tile. So look. This is why directional troweling is good. This is a fairly
big notch. You can the trowel ridges are not collapsed. There are air pockets in there.
And the back of the tile isn’t very well covered at all. There’s lack of coverage
here for the thinset. I don’t even know what this approach is in terms of the coverage.
Not good. Definitely not 90% to 95%. So that’s why directional troweling is super important.
For this next test, we do have directional troweling. All the ridges are running in the
same direction. And we’re going to backbutter the back of the tile using the flat side of
the trowel. So we’re going to fill in all the voids. So we pretty much have almost 100%
coverage on the back of this tile. So this is backbuttered with the flat side of the
trowel. Now we’re going to embed it into the directional ridges here. And we’re going
to move the tile back and forth. We’re going to collapse the ridges. All right.
Now let’s take a look at the back of this tile. So as you can see here, we’ve got
great coverage. All the ridges were collapsed. The air is allowed to escape from those ridges.
So when you collapse the ridges, the air is expelled from them. And you collapse the tile
onto the thinset, and you get great coverage. As you can see, all the voids in the back
of the tile are covered in thinset. And it’s really the collapsing of the ridges that provides
the coverage. This final test, we have directional troweling.
So all of the thinset is in one direction on the substrate. And we’re also going to
do directional troweling on the back of the tile. So the direction of the notches on the
back of the tile match the notched pattern on the substrate. So what we’re going to
do is adhere this tile to the substrate. I’m going to clean this tile off in a second.
But we’re going to collapse the ridges. We’re going to move this tile back and forth
just a little bit to collapse those ridges. Expel all the air out of the thinset.
All right, let’s take this tile off the KERDI-Board. And again, you get great coverage
when you use directional troweling, and you use the double-notch technique.
Well that’s it. Hopefully you like these quick tips and they help you out with your
own project. Make sure you subscribe to Sal’s YouTube channel. It is phenomenal. If you’re
doing tile work, you definitely want to watch a lot of his videos.
And don’t forget to subscribe to Jeff’s channel because he has some really good information
in his channel, and I think you’re going to get some really good value out of what
he does. And don’t forget Home Repair Tutor as well.
Well thanks so much for watching and make sure you leave your comments down below. We’ll
definitely try to answer them, and we hope you have a great day.
And remember, subscribe.