Tile
Surface Preparation
A well-prepared surface is a critical component
to a good and lasting tile job.
The three best surfaces for tile installation
are cement, cement, and cement!
Although adhesive material manufacturers list
several surfaces as acceptable, the best surface by far is
a cement product.
A bare cement floor, a cement board floor or countertop underlayment, or replacement
cement board backer for walls are the best.
Cement floors:
If you have a floor tile job on the cement slab, make sure
the surface is relatively clean and dust free. Most residues
can be removed with a blade scraper (4 inch
blade or larger).
For cement residues left over from the slab installation,
use a cement brick. This
is a very coarse stone with the center mounted handle for knocking
off those high spots.
Within reason, take out irregularities making
the floor as flat as possible. Use at least a 4-foot straight
edge or level to check older floors for the high and low spots.
(This will come in handy later when you lay out your job).
For floors that have excessive high and low spots,
a floor leveling product can help. These are
cement products that are self- leveling and when mixed properly
will flow easily into low spots.
If the your floor has excessive cracking and
is very irregular, a structural problem may be indicated. The
cause of the structural settlement must be corrected. Otherwise,
the surface may not be a good candidate for the weight of a
tile floor.
The only other preparation for a cement floor
is an acrylic floor primer. This is a milky
white liquid that is applied with a brush or roller. It helps
to bond the cement floor to the bedding mortar, which is critical.
Wood floors:
If your floor is not cement it most likely will fall in the
basic wood floor category. Regardless of the floor covering
(like carpet or vinyl), most floors built on floor joists
(framing members) have wood sub-floors.
Sub-floors are mostly comprised of two wood layers,
while some newer sub-floors only have one 3/4" inch layer.
You will probably need to remove the old floor covering such
as old ceramic tiles, carpet, vinyl tiles etc.. One exception
might be sheet vinyl or vinyl tiles that are applied directly
to the subfloors. Cement board underlayments can reasonably
be attached to these thin materials without adding significant
height to the overall job.
Once the necessary floor coverings are removed,
remove old glues or cement residue by scraping with the blade
scraper tool. You don't need to remove every little bit, but
enough to make the floor reasonably level.
Also, depending on the existing floor covering, you may need to remove old underlayment
materials such as a thin quarter inch plywood used with many sheet vinyl floors.
If you are taking out old carpet, the carpet tack strips along the perimeters
and any staples used to hold the carpet pad in place need to be removed or pounded
down flat.
Check the wood to sub-floor for damage. In bathrooms, for example, the top floor
layer could be significantly damaged from a seeping toilet or tub/shower overflows.
Overall, the basic wood floor sub-surface must be structurally solid, although
it need not be cosmetically pretty. Once you have a solid and flat sub-floor
surface, you are ready to apply cement board underlayment.
Walls:
The basic principles of stud-framed walls are similar to wood
floors.
Interior residential walls are usually plaster
or half-inch drywall. The main material to be removed from
walls, like in a tub surround, is the existing tile. Many people
try to remove the tiles (usually installed with mastic glue
over drywall) in order to re-install tiles. This is usually
more work that is necessary and results in an irregular surface.
Too much glue is left behind and many times the drywall comes off with the
tiles leaving holes. Also, in water areas like showers, usually the drywall
has been water damage and needs to be replaced anyway.
The best way to demolish a shower or tub surround for remodeling is to score
the drywall or plaster along the line appropriate to the
new tile set (and hopefully along a line centered on a framing member) and
remove the wall surface, tiles and all.
This leaves you with a clean framing
wall on which to installed new cement backer board, which is the best
surface for tile installation.
Keep in mind that the new cement board needs to be installed
flush with the old surface material. This is relatively simple
if you're removing one half-inch drywall and replacing it
with one half-inch cement board. But if you are removing
plaster, which can vary in thickness from 1/2 inch to over
1 inch, some shimming to other framing members will be necessary
so that the one half-inch cement board meets the existing
surface on the same plane.
A key element to this demolition procedure is the appropriate place to score
or cut the existing material. You should have an idea as to where the line
of the new tile will fall and then cut between one and two inches inside
that line.
When the new tile is installed, the last pieces
along that line will jump the seam between the new and old
surface alleviating the need for seam patch and finish work.
If you can locate an existing vertical stud that is appropriate to the new
tile job, make your cut centered on that stud. If you make a cut that corresponds
to your new tile set, but does not correspond to an existing stud, an additional
stud or attachment member can be installed there.
Now that you have demolished the existing walls and positioned attachment framing,
you're ready to attach cement backer board.
All the best and good luck!
|
