Lath and plaster

Lath and plaster is a wall or ceiling construction method in which wet plaster is applied over narrow strips of wood or another backing material. The plaster presses through gaps in the lath and hardens into a continuous surface.

Wood lath: Narrow wooden strips fixed across framing to support plaster. Gaps between these strips let plaster form keys that hold the coating in place.
Gypsum plaster: A plaster whose binder is calcium sulfate hemihydrate, which sets after mixing with water. It became a common alternative to slower-setting lime plaster in interior work.
Plaster repair: The process of stabilizing or replacing damaged plaster while preserving sound material. Repair work must account for both the plaster surface and its attachment to lath.
Drywall: A panel made from a gypsum core faced with paper, used to form interior walls and ceilings. Drywall replaced much lath-and-plaster work because sheets install faster.
Plaster key: A knob or ridge of hardened plaster that grips the back of lath. Keys mechanically anchor the plaster coat to the lath.
Plaster: A workable material that hardens into a smooth coating for walls, ceilings, or other surfaces. Lath and plaster depends on plaster’s ability to be applied wet and harden in place.
Plaster ceiling: A ceiling finished with plaster applied over a supporting structure or base. Lath and plaster was widely used to create continuous ceiling surfaces.
Plasterboard: A rigid building board with a gypsum core, used as a base or finish for interior walls and ceilings. It can provide a continuous plaster backing without narrow lath strips.
Scratch coat: The first plaster layer, scored while wet to help the next coat adhere. This base coat begins the layered application over lath.
Stud wall: A framed wall built from vertical structural members called studs. Studs provide the framework to which wall lath is commonly attached.

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