K&B: Top Five Tile Callbacks
Do any of the following complaints sound familiar?
"Help! We just had a party and our five-year-old tile floor is
cracked all over."
"My contractor just put in a wheelchair-accessible shower for
our daughter, and now water is leaking through into the
"The contractor says my tile is growing, and now I have a big
hump in the floor. How do I make it stop?"
"My grout is all soft and powdery, and it comes out when I
vacuum. The contractor came out and put water in it and said it
would make it harder. But it didn't work."
I gleaned these comments from calls I received the week before
I wrote this article. Sadly, as director of the Ceramic Tile
Education Foundation, I hear nearly identical complaints almost
every week. The worst part is that all of these problems are
installation related, which can cause a tile professional like
me to be downright depressed.
Why all the problems? In probably 98% of the cases, the
reason, pure and simple, is failure to follow instructions and
observe established installation guidelines. I never thought,
during my nearly three decades as a tile contractor, that the
day would come when I would agree with that statement. However,
after four years of fielding tile-related complaints in my new
position, I must report that it's true.
In compiling my list of the top five tile failures, I
consulted with Bob Daniels, executive director of Tile Council
of America (TCA), and Noah Chitty of TCA Technical Services.
Combined, the three of us handle approximately 5,000 calls and
e-mails a year. Surprisingly, we all agreed on the top five
problems, although we ranked them somewhat differently. So
here, in random order, are the top five tile-failure calls we
Lousy Floor Prep
Substrates must be clean -- meaning free of all foreign
matter, paint, curing compounds, dirt, and anything else that
interferes with bonding. One contractor actually sent me a tile
with paint overspray and sawdust imbedded in the thinset. He
wanted to know why it didn't stick to the substrate.
When you're installing tile over concrete, cracks, joints, and
curing compounds must be dealt with. There is no such thing as
a "dead crack" (a term I hear often). If you encounter a crack,
you'll need to apply a crack-isolation membrane. But be aware
that not all membranes allow you to relocate the control joints
that are already in the substrate.
Be sure to read the multipage directions that come with the
product; don't rely on the summarized directions printed on the
box or bucket.
Wrong Thinset, Poor Coverage
If you set much tile, you're sure to encounter a variety of
substrates, tile types, and installation conditions. Happily,
there is a thinset mortar available for every application, so
use the right one! Manufacturers don't make six to ten types
just so they can charge different prices. They are different
products with different properties and recommended uses.
Once you've obtained the proper product, you'll need proper
coverage. That's important in the installation of all types of
tile, and it's particularly critical when large-format tile
(8x8 inches or larger) is used.
On interior substrates, you should have evenly distributed
thinset over 80% of the surface; for exterior or wet areas, the
requirement is 95%, evenly distributed. The trowel notch-size
instructions listed on the bag of thinset are general
recommendations, not gospel. The manufacturer has no way of
knowing whether you'll be installing lug-back, waffle-back,
ribbed-back, or some other type of tile.
Most products contain a reference to ANSI A108,
Specifications for the Installation of Ceramic Tile,
which is where you will find the rest of the requirements for
proper installation. (ANSI A108 is available from TCA for $15;
www.tileusa.com, 864/646-8453). Encourage
your installers to practice troweling in one direction on
large-format tile, and you will be far less likely to get
customer complaints about cracked tile or broken corners.
No Movement Joints
A thorough discussion of movement accommodation joints would
take many pages to address. Tile expert Bob Young once wrote
that many tile installations are held down by the Three Gs:
God, Grout, and Gravity. However, even the Three Gs have little
influence on the integrity of an installation if the tiles have
nowhere to move.
All building materials move, each at a different rate. This is
a problem that must be considered in every installation,
regardless of size.
Packing grout into the wall line at the perimeter of the room
is a leading cause on the failure list. A minimum 1/4-inch
joint along the entire perimeter of the installation must
remain free of grout, backerboard, and thinset (see
Floor tiles must be allowed to move. At
the edge of a room, leave a gap between the backerboard and
tile and the wall. If there is no baseboard, finish the gap
with backer rod and caulk. Don't use grout; it will
Where there is no baseboard, use backer rod and caulk to fill
the gap at the perimeter. If an installation is regularly
exposed to sunlight, you must place movement joints at
intervals no greater than 12 feet. Complete recommendations are
contained in the TCA Handbook under detail EF171.
Many consumers, and apparently some builders, have the
misconception that tile and grout constitute a waterproof
surface. A gentleman recently called me about the shower in his
new $500,000 home, which he said had been installed three times
and was still not right. The first time, the installers didn't
realize that they needed waterproofing; once they became aware
of the requirement, they put it in incorrectly.
Waterproofing should be considered for any tile installation
that will be subjected to more than moderate moisture levels --
an occasional spray, for instance.
This is one aspect of tile installation where manufacturers
have excelled, in particular with trowel-on membranes, sheet
products, and even preformed curbs, jambs, and entire shower
bases. Nevertheless, the skill level required for this work
goes beyond what's needed to install floors.
To work as designed, any waterproofing system must be properly
installed; in fact, the margin for error is zero. If the
installer fails to install vapor membranes behind walls where
required, or drives nails through the bottom 8 inches of the
shower pan, or nails backerboard curbs through the membrane, he
won't have to wait long before the dissatisfied customer tries
to relieve him of his wallet.
Improper Installation of
All the benefits of using backerboards are rendered useless
unless specific installation instructions are followed. For
example, all backerboards intended for floor use require a
leveling bed, not just a little thinset and a few fasteners.
Let me repeat that: A leveling bed is required!
The purpose of thinset under the panel is not confined to
bonding. It also provides a solid, void-free backing surface.
Some backerboard manufacturers specifically do not want the
panel bonded, so they recommend dry-set mortar for the leveling
Proper fasteners are critical: It's their job -- not that of
the thinset -- to secure the panel. Minimum head diameter for
backerboard fasteners is 3/8 inch. This means no drywall
screws! Galvanized roofing nails are acceptable, however. When
using pneumatic nailers, you must place the head of the gun
firmly against the backerboard surface before you pull the
trigger. This helps prevent the panel from resting solely on
the ridges or, even worse, riding up the nail.
Leave gaps between sheets and treat them according to the
manufacturer's recommendations. If you don't leave appropriate
gaps in the supporting wood panel, edge swelling may push the
whole backerboard off the floor, resulting in tile cracks at
the sheet perimeter.
Finally, backerboards are nothing more than backerboards. They
provide no structural value. If the subfloor provides
inadequate support, backerboard is not an answer.
Keep in mind that subfloor recommendations are minimums. You
need adequate strength to support the tile job. If the subfloor
has been open to the weather and has delaminated or swollen,
you may need to replace it or add a new layer to get the
strength back.Dave Gobis is a third-generation tile setter and the
executive director of the Ceramic Tile Education Foundation
(CTEF, 864/222-2131, www.tileschool.org).