Intro
| The Tile-Making Process | Historical
Background | Ceramic Floor Tile Types | Laying
Ceramic Tile Floors | Historic Ceramic Floor Tile: Preservation and
Maintenance | Historic Ceramic Floor Tile: Damage and Deterioration
Problems | Historic Ceramic Floor Tile: Repair and Replacement | Summary | Some Sources for Replacement Tiles
Loss of Tile Surface and
Pattern. Ceramic tiles are among the most durable of historic flooring materials, but
natural wear and a certain amount of deterioration or damage is inevitable. Some tiles,
such as dense, close-textured quarry tiles and ceramic mosaic tiles, resist abrasion and
stain absorption very well. But many others, especially patterned encaustic and geometric
tiles, are extremely susceptible to abrasion. Heavy traffic can also result in uneven
wear, or even cupping, in certain areas of tile floors that get more use than others, such
as doorway entrances. The particular clay mix, or the dye or pigment used to color the
clay, can also affect the hardness and durability of individual tiles or an entire ceramic
tile floor.
Tile Glaze Failure. Occasionally some glazes can become pitted or powdery as
they age. Lead glazes used in the 19th century, which were fired at low temperatures,
deteriorated relatively quickly. Glazes have different physical properties from the fired
clay tile body itself, and as a result may sometimes crack or craze. Unless the crazing
visibly extends into the porous clay of the tile body beneath, this is not generally a
serious material failure; however, dirt entering these cracks cannot be removed, and will
discolor the tile. If the crazing penetrates through the glaze, it may increase the water
absorption of the tile.
Tile Breakage. Ceramic floor tiles are very susceptible to damage and breakage
caused when something heavy is dropped. Repeated passage of heavy objects, or carts, over
a floor can also crack and break ceramic tiles, as well as heavy vibration from outside
traffic.
Moisture Damage to Tile. Ceramic tile floors have been traditionally viewed as
highly waterproof systems that do not require protection from moisture. In reality,
however, this is not true. Water-related problems are one of the most common causes for
the deterioration and failure of historic tile floors, particularly in bathrooms and other
rooms where there is a lot of moisture. Water that is allowed to sit in areas around
shower stalls and bathtubs can eventually damage grout and mortar, and loosen tiles. Some
of the more porous kinds of tiles that are not as hard-fired may actually begin to powder
or spall if subjected to constant moisture.
Loose, Cracked, Broken or Unbonded Tile due to Mortar Failure. The durability of
ceramic tile floors depends to a great extent on a sound mortar bed and sound mortar
joints. The wrong mortar type or mortar that is inadequately mixed can also spell trouble
for a ceramic tile floor. Failure of a tile floor system laid over a subfloor is often the
result of weakened or deteriorated grout or mortar which allows the tiles to become loose.
Mortar may also be weakened or loosened by cleaning solutions that are too strong.
Proper tile-laying technique includes the use of a material that will allow for some
movement of the tiles. Traditionally, a layer of asphalt (replaced by a layer of plastic
or building paper in more modern construction) was inserted to separate the base and the
bedding underneath. This prevents bonding between the base and the bed, and allows for
some "relative" movement. It is intended to prevent the ceramic tile floor from
arching or ridging, a condition in which single or entire rows of tiles can pop up to
relieve tension and separate completely from the bed. When this happens, the condition
will probably require taking up and relaying many or all of the tiles.
Tile Damage or Loss caused by Systems Update. The installation of new plumbing,
electrical and HVAC systems, or the attachment of new fixtures and furnishings, may be one
of the most common sources of damage to an historic ceramic tile floor. Earlier remodeling
projects to remove old pipes or to replace "out-dated" bathroom fixtures may
have resulted in the loss of floor tiles. Different shapes and sizes of new fixtures,
equipment or pipes may have exposed previously untiled areas that have been
inappropriately patched with cement. Careless workers and insensitive installations can
also result in damage, breakage or removal of historic floor tiles. All of these
conditions will require matching replacement tile.
