A lath or slat is a thin, narrow strip of straight-grained wood used under roof shingles or tiles, on lath and plaster walls and ceilings to hold plaster, and in lattice and trellis work.
Sawn lath, seen from the back with hardened plaster from the other side showing through. Sawn lath became popular after the introduction of the circular saw in the 19th century.
Roof laths span across between the rafters and support the wood shingles.
Riven lath, each piece has been split from a log
Bostwick Steel Lath Company advertisement for steel truss loop type metal lath in 1920
Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. The term stucco refers to plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces.
Stucco plaster reliefs, such as this work at the Chateau de Fontainebleau, were hugely influential in Northern Mannerism. A plaster low-relief decorative frieze is above it.
Applying mud plaster to an outside wall
Clay plaster base coat on split oak lath held in place with straw and manure, covered with a lime plaster top coat, Old Economy Village, Pennsylvania (1827)
Lime setting-coat on clay plaster with straw binder. Applied to hand-split lath over a timber framed wall of a brick family house at Old Economy Village, Pennsylvania