What You Need to Know
Before Laying Tile on Concrete
Although putting tile directly over concrete is a common practice,
there are a couple issues that need to be addressed to be sure
your project stands the test of time, and won’t cause issues down
the road that could have been easily addressed up-front.
The two most important factors are Moisture and Foundation
Shifts. Generating a flat, dramatic tile floor doesn’t have to be
hard if you plan ahead and take the necessary steps.
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The Uncoupling Membrane
You need to “uncouple” the tile from the concrete. An
uncoupling membrane placed between the tiles and the
concrete slab will help stop the concrete shifts from
transferring to the tile above it. The name says it all; the flexible
uncoupling membrane detaches the tile from the concrete
floor. This layer allows the tile to stay stationary even if the
sub-floor shifts. This uncoupling membrane is made of
polyethylene and not only prevents your tile from cracking,
but it also acts as a barrier to moisture. This is well worth the
time and effort as this will prevent your concrete problem from
expanding into a tile problem.
However, this solution has its limitations. If the concrete
floor shifts dramatically and large cracks develop, the
membrane may not have the necessary stretch to uncouple the
top surface enough to prevent the crack from being transferred
to the grout or tile.
Picking the Right Tile
Your concrete floor is now ready to have ceramic or porcelain
tile applied on top of it. The final step is choosing the right tile
for the amount of trafic the floor will receive. Different tiles are
rated differently and you need to pick the right tile.
It is important to deal with a professional tile and stone dealer
before making these decisions. GENROSE Stone and Tile
is a design driven company, providing a wide selection of ceramic and porcelain tile across the Northeast.
UNCOUPLING MEMBRANE
MUUTOS PORCELAIN TILE
ASPIRE PORCELAIN TILE
WYNN PORCELAIN TILE
Let’s look at Moisture and Foundation
Shifts in greater detail.
Moisture can come up from the concrete slab and affect the
underside of your tile as well as the adhesive you are using.
There is a simple way to test for moisture. Start with a 2 ft. x
2 ft. sheet of plastic. Lay it on the slab in an area that is not
affected by sunlight. Tape it securely to the concrete slab so no
air can get in. Be sure you keep your thermostat at a constant
temperature during this test. After three or four days, check to
see if there is any moisture on the underside of the plastic. If
you do find moisture, you should not apply the tile directly to
the concrete since the moisture can damage the mortar which
will loosen the tiles. You should seek the help of a professional
to seal the slab before moving forward.
Sweep the floor thoroughly. No matter how clean the floor
may look, sweep it carefully including into the corners.
Scrub the floor. This will remove anything the sweeping
cannot eliminate including stains and dried on deposits. Use a degreasing cleanser and a scrub brush to be sure you get any oily and greasy patches. Do not use chemicals on the floor, but you should use a little elbow grease.
Rinse with warm water and dry with towels (do not air dry).
Give the floor at least 24 hours to thoroughly dry.
Locate any cracks in the floor and patch them; this includes
hairline cracks that may grow. Use a professional concrete
patching product and a trowel. Be sure to smooth it out so
there are no bumps or high points on the floor. When dry,
scrape the area to ensure the surface is perfectly flat or you
could cause a tile to rock or crack on a high point. Follow the
directions on the compound for drying time.
Use the concrete patching product to level any indentations
or depressions in the floor. Use the trowel to make sure the
area is flat and there is no extra patching product left on the
floor. Always allow 12 to 24 hours for the deeper depressions
to dry.
Sweep up any left-over dust and patching remnants and
then apply a concrete sealer. This will help protect against
any seepage of moisture from the slab to the tile and grout.
Apply evenly and cover into the corners. Allow to dry
completely.
Laying down an uncoupling membrane is an optional step. If
you decide that the uncoupling layer is needed, you would
lay it over the dried sealer. Make sure it is laid evenly and flat.
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“Generating a flat,
dramatic tile floor
doesn’t have to be
hard if you plan
ahead and take the
necessary steps”
Preparing the Concrete
Preparing the concrete slab for a tile installation is pretty
straight forward, but each step is designed to assure you will
end up with a flat tile floor that looks great and will stand the
test of time.
If you do not find moisture,
the second issue you need to
address is cracks in the slab.
Foundation shifts can adversely
affect your concrete slab.
Installing tile directly on a slab
that has even minor cracks can
be an issue. Very small cracks
of 1/8th of an inch may be filled
using a high-quality modified
thin-set mortar. Although
your floor may look relatively
good now, the condition can
change over time. When the
foundation of the home shifts,
and most do have minor shifts
over time, the concrete slab
can develop hairline cracks that
can grow larger. Porcelain floor
tile cannot compensate for
these shifts.
Tile has no ability to bend or stretch. As the concrete shifts,
the tile will shift with it. To make matters worse, the grout that
is used to fill the seams also has no flexibility and will crack as
well. The shifting that produces the cracks in the concrete slab
will also produce cracks in the tile and/or grout. Thankfully,
there is a solution to this problem.
CONCRETE
DIRECTLY OVER A
CAN I SET
FLOOR?
WYNN PORCELAIN TILE
