Lath is a thin, narrow strip of straight-grained wood used in construction for various purposes. It is used under roof shingles or tiles, on lath and plaster walls and ceilings to hold plaster, and in lattice and trellis work. Lath is also used on many tobacco farms in the Connecticut Valley as a means to carry and hang the plant in barns.

Lath and plaster is a building process used to finish mainly interior dividing walls and ceilings. It consists of narrow strips of wood (laths) which are nailed horizontally across the wall studs or ceiling joists and then coated in plaster. The lath-and-plaster method has its upsides, such as moisture prevention, and is still used today in building construction to form a base or groundwork for plaster.

In addition to wood lath, various types of metal lath began to be used toward the end of the 19th century. Metal lath is categorized according to weight, type of ribbing, and whether the lath is galvanized or not. Metal lathing was spaced across a 13.5-inch center, attached by tie wires using lathers nippers. Sometimes, the mesh was dimpled to be self-furring. Metal lath is often used in bathrooms and kitchens, where ceramic tile is applied over a plaster base.

Overall, lath is a versatile material used in construction for various purposes, including as a base for plaster in the lath-and-plaster method.