Lath

Lath is a construction material consisting of thin, flat strips used as a base or framework for finishing surfaces such as plaster, stucco, or, in some cases, drywall. It provides mechanical keys and support for the finishing layer.

Wood lath, the traditional form, uses narrow strips of softwood nailed horizontally to wall studs or to furring strips, creating a rough lattice. Plaster applied in coats keys to the lath as it sets, forming a rigid wall. Spacing and thickness vary by region and era, but the lath must be wide enough to support the plaster and allow ventilation. Nails or staples secure the lath to the framing.

Metal lath includes expanded metal lath and welded wire lath. These metal products substitute for wood lath in many 20th-century buildings, providing a uniform base with greater rigidity and moisture resistance. They are attached with nails or staples and are used with plaster or stucco finishes.

Modern practice: In most new construction, drywall has replaced lath and plaster. Lath remains in many older buildings and in restoration projects where authenticity is required or where plaster finishes are preferred for their acoustical or aesthetic properties.