L cut

A piece of tile cut or shaped to the letter L.

Laitance

A layer of weak and nondurable material containing cement and fines from aggregates, brought by bleeding water to the top of overwet concrete; the amount of which is generally increased by overworking or overmanipulating concrete at the surface by improper finishing or by job traffic.

Lap

The length by which one bar or sheet of fabric reinforcement overlaps another.

Latex

A water emulsion of a synthetic rubber or plastic obtained by polymerization and used especially in coatings and adhesives.

Latex-portland cement grout

A portland cement grout with a special latex additive which results in a less rigid, less permeable grout than regular portland cement grout.

Latex-portland cement mortar

A 'mixture of portland cement, sand, and special latex additives which is used for bonding tile to back-up material. It is less rigid than portland cement mortar.

Lath

A wood strip or metal mesh, which acts as a background or reinforcing agent for the scratch coat or mortar coat. (TCA)

Layout stick

A long strip of wood marked at the appropriate joint intervals for the tile to be used. It is used to check the length, width, or height of the tilework. A common name for this item is idiot stick.

Leadless glaze

A ceramic coating matured to a glassy state on a formed article, or the material or the mixture from which the coating is made, to which no lead has been deliberately added. (ASTM C 21) NOTE: This does not imply that the glaze is nontoxic or that it contains no lead. Because of plant practices and conditions, a small percentage of lead,, 0.1 to 0.2% (by dry weight), expressed as lead monoxide, may be present.

Leg

A tile wall running alongside a bathtub or abutment. This term sometimes is used to describe a narrow strip of tile floor.

Leveling coat

See Plumb scratch.

Light duty tile

Tile suitable for limited pedestrian traffic such as entryways in single family residences.

Lime

Specifically, calcium oxide (CaO); also, loosely, a general term for the various chemical and physical forms of quicklime, hydrated lime and hydraulic hydrated lime.

Limestone

A sedimentary carbonate rock, composed chiefly of calcite (Ca C0~, but sometimes containing appreciable dolomite. (ASTM C 21)

lippage

a condition where one edge of a tile is higher than an adjacent tile giving the finished surface an uneven apperance

Live load

Any load that is not permanently applied to a structure.

Load-bearing wall

A wall designed and built to carry superimposed vertical and shear loads as opposed to nonload-bearing walls.

Loss on ignition

The percentage loss in weight of a sample ignited to constant weight at a specified temperature, usually 900-1000 C.

Lugs

See Self-spacing tile.