from active cracks, and level or plumb within
1⁄8 in. in 10 ft. (If it’s an out-of-level floor, see
“Applying Leveling Compound” on p. 463.)
If you’re tiling basement surfaces, the big
issue is cracks. If masonry cracks expand and
Create a level mortar bed by drawing a metal screed board across two float
contract seasonally, it’s unwise to tile over them
strips pressed into mortar columns. After the mortar has been screeded, the
because the tiles will crack. Likewise, if one side
wood float strips are removed and their voids filled with mortar.
of a crack is higher than another, it’s probably
caused by soil movement. (If the crack is inactive
and both sides are level, you can vacuum out the
with water, and pouring the mix onto a floor. You
S a f e T y a l e R T
crack, dampen it, and fill it with a latex thinset
don’t even need to spread it around much. It
adhesive before applying the thinset setting bed.)
flows like water, levels itself, and starts to harden
older resilient flooring some-
in about 15 minutes. Well, that’s a bit oversimpli-
Dry installations. Unpainted drywall is an
times contains asbestos, which is
fied but not by much.
acceptable setting bed for dry installations. (In
seldom a problem unless fibers
First, be sure the substructure is sturdy
damp or wet installations, never adhere tile
become airborne. before sanding
or abrading it, take a sample to a
enough to bear the weight. Specs for one popular directly to drywall.)
flooring specialist, who can tell
SLC, LevelQuik, recommend at least a 3⁄4-in.
In dry installations, use at least 5⁄8-in. drywall
if it’s asbestos. next, consult a
exterior-plywood subfloor over joists spaced up
if attaching it directly to studs 16 in. on center.
local building code officer, who
to 24 in. on center; use two 1⁄2-in.-thick pours to
Or sandwich two layers of drywall, with a layer
can tell you if it’s safe to install
achieve a 1-in. optimal thickness. Wait 24 hours
of adhesive between, to create a more rigid lami-
new flooring or if you must hire
between pours. Whatever the substrate, it should nation. But if you install a double layer of dry-
an asbestos-abatement specialist
be clean, dry, and free of chemicals—such as
wall, offset the panel edges by at least 16 in.
to remove the old flooring.
Stronger inSTAllATiOn, leSS WASTe
Construction adhesive is often used to join backer board to other substrate layers, but
thinset adhesive (applied with a 1⁄4-in. square-notched trowel) creates a far more
rigid lamination. When installing backer board, cut pieces lengthwise if possible. For
example, if you have 2-ft.-wide countertops, cut a single piece of backer board 2 ft. by
8 ft. rather than into two 2-ft. by 4-ft. pieces. The panel will be slightly stronger,
there will be no waste, and you’ll have one fewer seam to tape and top.
464 chapter 16
To avoid cutting handmade tiles on
the tub sidewall, the installer laid out
tiles on the floor, using plastic
spacers to simulate grout joints. She
then adjusted the thickness of mortar
beds on the tub walls so that the tile
assembly fit exactly. (Vacuum floors
well before laying tile on them
because dust can compromise a
setting bond.)
In either case, leave a 1⁄8-in. gap between panel
odd or ProbleMatic Setting bedS
edges, cover the joints with self-sticking fiber-
The beds described next may require special
glass mesh tape, and then apply a layer of latex
techniques and materials.
thinset adhesive over the tape. Drywall tools are
fine for this application—but not drywall joint
Plastic laminate countertops are acceptable
tape or compound. When installing drywall as a
setting beds if they’re solidly attached. Scuff the
setting bed, you don’t need to fill screw holes or
surface with 80-grit sandpaper, wipe with a rag
feather out joints perfectly smooth because you’ll dampened with solvent to remove grit and
be covering them with thinset and tile.
grease, and fill any voids. Then use an epoxy-
based thinset to bond the tiles. Alternatively, you
Plywood beds. Plywood is not recommended as
can cover the old laminate with 1⁄4-in. backer
a setting bed, but if you must use it, use only
board, adhering it with an application of epoxy
exterior grade and leave 1⁄8-in. gaps between the
thinset and 1-in. corrosion-resistant screws
panel edges. Plywood substrates for floors and
spaced every 6 in. around the perimeter of the
countertops must be at least 11⁄8 in. thick—best
countertop and every 8 in. in the field. Sink screw
achieved by laminating a 1⁄2-in.-thick plywood
heads flush, vacuum the backer board, and use
underlayment panel to a 5⁄8-in. plywood subfloor.
latex or epoxy thinset adhesive to bond tiles.
To prevent squeaking and to stiffen the assembly, Note: The recommended 1-in. screw assumes the
apply construction adhesive between the panels.
combined thickness of the countertop materials
Offset the panels so their edges don’t align. In
is at least 11⁄8 in.
addition to the adhesive, use 1-in. corrosion-
resistant nails or screws spaced every 6 in. To
Tiling over existing tile is a reasonable alterna-
secure this laminated plywood to the joists, drive tive to ripping it out, as long as the old tile isn’t
16d galvanized nails into the joist centers. To
cracked and is well adhered and the substrate is
avoid high spots that might crack the tiles, sink
solid. Scuff the tile with a carbide-grit sandpaper.
all screw or nail heads below the surface of the
Vacuum the surface well, and wipe with a damp
top layer. Sand and vacuum the plywood before
rag. Because tile surfaces are not perfectly regu-
notch-troweling on an epoxy thinset adhesive.
lar and grout joints are recessed, first use a flat
tiling
465
trowel to spread a layer of epoxy thinset to build
sandpaper, and wipe with a damp rag. Use a
up grout joints and level the surface. Wait a day.
latex thinset adhesive.
Then use a notched trowel to apply a setting bed
Other situations
of epoxy thinset.
Papered walls? Strip ’em! Vinyl wall
Two caveats: Because of the risk of leaks, don’t coverings are supposedly tenacious enough to
tile over tiled shower-stall floors. Rather, tear out
support tile, but it’s risky.
the old floor, replace the shower-pan membrane,
Veneer paneling? Not recommended.
and tile atop a newly floated mortar bed. Second,
P R O T I P
Typically 1⁄4 in. to 3⁄8 in. thick, it will flex,
&nbs
p; don’t install tiles 2-in.-sq. or smaller over existing cracking grout joints and eventually
tile because they will telegraph the old surface’s
once you’ve established a
dislodging tiles.
irregularities. Instead, use large tiles.
room’s two main (perpendicular)
Wainscoting or lumber flooring? Not
control lines, snap as many sec-
Resilient flooring is acceptable if there’s a sin-
recommended. Solid wood expands and
ondary layout lines as you like.
gle, uncushioned layer that’s well adhered to a
contracts, and all those board seams would be
Many tile setters also snap lines
stable subfloor. Cushioned or multilayered floor-
a nightmare to fill.
around the perimeter of the room
ing will flex too much to be a stable base for tile,
to indicate where cut tiles begin;
so, to be sure, use a utility knife with a hooked
they set all the full tiles within
blade to cut out a cross section of flooring in an
Tile Estimation and Layout
the lines first, then set cut tiles
inconspicuous spot.
At this point, we’ll assume that the substructure
at the base of walls, cabinets,
is sturdy and stable and the setting bed is in
and fixtures.
Painted walls are OK as long as the paint is well place. Careful layout is the key to a good-looking
attached and the wall doesn’t flex. Drill a small
job, so don’t begrudge the time it takes. The right
exploratory hole to determine the composition
layout will align tile joints correctly, create a
and thickness of the wall. If it’s drywall less than
5
pleasant symmetry, allow you to cut tiles to size
⁄8 in. thick, install a layer of 1⁄4-in. or 3⁄8-in. dry-
beforehand, and—most important—enable you
wall over it. If the wall is traditional plaster
to set tile accurately and quickly while the clock
(hard to drill through), it’s probably fine. Prep
is ticking for that fast-drying adhesive.
painted walls by sanding them with 100-grit
eStiMating tile
If you’re installing a popular tile that a local sup-
Storytel ing plier has in stock, wait until you’ve installed the
setting bed before estimating tiles. If you order
A story pole (also called a jury stick) is like an oversize yardstick but is divided into
too many, most local suppliers will take back
units that represent the average width of one tile plus one grout joint. Story poles
extras, as long as they aren’t damaged or
give you a quick read on the number of full-size tiles you’ll need to get from point A
returned too long after purchase. Ordering tiles is
to point B. For these homemade measuring devices, any straight board will do.
not complicated unless surfaces to be tiled have a
lot of jogs, recesses, odd angles, and obstacles.
Using a tape measure and a pad of graph paper,
calculate the square footage of the surface to be
tiled and add 8% to 10% for waste, damage, and
future repairs.
Handmade or exotic tiles are another story.
Because they’re expensive and must be ordered
well in advance, suppliers rarely accept returns.
To save money, try to draw layouts that are accu-
rate to an inch so you can count individual tiles.
But you should still order extra tiles—say, 5%
above your tile count—which is preferable to
waiting two months for the next tile shipment
from Italy. Besides, tile colors can vary greatly
between batches. Your detailed drawings will
also help you accurately frame out the area to
be tiled.
Finally, when ordering tile, calculate the num-
ber of trim pieces separately from your calcula-
tions for field tiles. For each distinct piece of tile
trim (such as surface cove, V-cap trim), add 15%
to the lineal feet of trim indicated by the layout.
466 chapter 16
Order at least two specialty trim pieces for any
Use full tiles at focal centers. A focal center
one-of-a-kind piece (such as radius-bullnose down is any area that the eye is drawn to: the front
angle). This is also the time to order compatible
edge of a counter; a room’s entryway; or a center
adhesives and color-matched grout and caulk.
of activity such as a sink, large window, or
hearth. Common sense says full tiles look better
tile layout
than cut tiles, so put full tiles in conspicuous
areas. Conversely, put cut tiles where they’ll be
Most tiles are square or rectangular. So the most
least noticed.
common floor-layout dilemma is in imposing a
grid that’s basically square onto a room that
Cut as few tiles as possible. Cut tiles are extra
isn’t. Laying out walls and countertops is much
work, and they don’t look as good as whole tiles.
the same, except that wall layouts are more
To avoid cutting tiles, you might be able to shift
affected by plumb. Wherever they occur, though,
the layout a little to the right or left or slightly
layout lines have the same purpose: They keep
vary the width of tile grout joints.
tile joints straight. When setting tile, it’s easy to
Make layouts as symmetrical as possible. This
obsess about individual tiles and spacers, getting
rule is both an extension and, occasionally, a con-
lost in close-up details. Layout lines help you
tradiction of the two above. Imagine a kitchen-
keep the big picture in view and keep tile joints
sink counter: The sink is certainly a focal center
from straying.
but may be smack-dab in the middle of a tile
field. There’s often no way to avoid cutting tiles
Four tiMe-teSted tiPS oF tiling
around the perimeter of a sink. In that case, try
Although the following rules make sense most of
to shift the layout (or the sink) so that you can
the time, bend them when you must.
cut tiles an even amount on both sides of the sink
(see the bottom drawing on p. 473). The result
Tile layouts impose a grid that’s basically square in a room that often isn’t. Start by recording
zzzzzz tiling a Floor
the room’s dimensions, use a framing square to see which corners are square, and note any
obstacles to be tiled around.
FIRST CONTROL LINE
SECOND CONTROL LINE
PARTIAL TILES
Field of
First
Second
Start tiling where
Cut and install
vision
control line
control line
control lines meet.
partial tiles last.
Full tiles at threshold
If the doorway is the focal center
The second control line is
Place angle-cut and partial tiles
of the room, use a story pole to
perpendicular to the first,
away from the room’s focal center.
find the tile-joint mark closest to
intersecting it roughly midway
Because cutting tiles takes longer
the middle of the doorway. Ideal y,
along its length. Although you can
than installing full tiles, most
the first control line will run
start setting tiles anywhere, it’s
installers cut tiles after the field of
through that mark, and there will
best to start where control lines
full tiles is in place.
be full tiles along the threshold.
meet in the highly visible middle
of the room.
tiling
467
will look much better than almost-full tiles on
lining uP the tile grid
one side and narrow tiles on the other.
Floor layout begins by identifying the focal point
This also is a good rule for small counters,
of the room and snapping two chalklines ( control
which you can see from side to side without turn- lines) onto the setting bed perpendicular to each
ing your head. If you must cut tiles, split the dif-
other. In the photos on these two pages, the door-
ference at each end.
way is the focal point of the room. Thus, the first
Don’t use tile pieces half size or smaller.
control line will run through the middle of that
They’ll look terrible. It’s better to adjust the width doorway and continue across the room to the
of tile joints. Or shift the layout so that you have
opposite wall at roughly a right angle.
large cut tiles on both ends rather than a row of
Full tiles look best in a doorway, so the
narrow ones on one end alone.
installers butted uncut tiles against the thres-
hold and continued the tile course until it met
Tiling a Floor
an adjacent wall. Then they selected a tile that
was roughly in the middle of the doorway, and
Using a framing square and a tape measure,
along one side of the tile, they stretched a taut
check to be sure the room’s corners are square
chalkline that ran across the room to the oppo-
and parallel. Make a quick sketch of the room,
site wall. As two people held the string taut, a
showing which way corners diverge. Or sketch
third person measured from the string to the
this directly onto the setting bed.
adjacent wall to make sure that the string was
parallel to the wall.
Floor lAyoUT
applying thinset adhesive
once you’ve snapped layout lines and vacuumed the setting bed one last time,
Renovation 4th Edition Page 109