lath

Lath seen from the back with hardened plaster from the other side showing through

A lath is a thin, narrow strip of some straight-grained wood or other material, including metal or gypsum. A lattice, or lattice-work, is a criss-crossed or interlaced arrangement of laths, or the pattern made by such an arrangement. Lath is the basic material used in the formerly common building technique known as lath and plaster, which was used to make interior walls.

Lath may also refer to wire mesh, typically with a paper backing, that is applied to a wood or metal framework as matrix over which stucco is applied. One of the key elements of lath, whether wooden slats or wire mesh, are the openings or gaps that allow plaster or stucco to ooze behind and form a stronger bond to the lath itself.

Name

The word stems from Old English laett, Mid. Eng. laþþe, a form possibly due to the Welsh liath; the word appears in many Teutonic languages, e.g. Dutch lat, German Latte, and has passed into Romanic, cf. Italian latta, French latte), denoting a thin, flat strip made of wood or possibly another material.

Uses

Today, wooden-slat laths are still used in building construction to form a base or groundwork for plaster (modern lath and plaster applications are mostly limited to conservation projects),^[1] tiles, slates, and other coverings, e.g. roofing. Such strips of wood are also employed to form lattice-work, or are used as the bars of venetian blinds or shutters. Riven lath is the stronger forerunner to sawn lath, as it was traditionally split with the grain from chestnut, oak, or similar hardwoods. Laths were also used to fix reed to a timber structure before plastering.

Wire-mesh lath is used extensively with stucco in home and commercial construction. In these applications the lath adds strength and rigidity in addition to providing a matrix to which the stucco can adhere. (This is similar to the way rebar is used to strengthen some concrete and masonry appications.)

Lath cut from spruce or balsam fir trees are used for building wooden lobster traps.

Historical significance

Inch-wide laths after the plaster has been knocked off (under stairs, Kent, UK)

Gypsum lath consists of gypsum plaster sandwiched between two sheets of absorbent paper. It was invented in 1910, and multiple variations were developed in the 1930s. Gypsum lath is commonly used in place of wood since it is noncombustible, easy to use, and gives better results. The lath and plaster method's popularity declined in the 1950s, as it was replaced by the more efficient drywall.

See also

Look up lath in Wiktionary, the free dictionary.

• Garden trellis
• Lathart
• Lattice truss bridge
• Plasterwork#Laths

References

 This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 

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