lath-and-plaster

Lath is a material used as a base for plaster in construction. Traditionally, it consisted of narrow wood strips nailed to structural members like rafters or joists. Modern lath can also be made from metal, gypsum, or insulated board.12

Metal lath, often used in areas like bathrooms and kitchens, is a mesh formed from expanded metal sheets. This creates an irregular surface that helps the plaster adhere effectively. Gypsum lath features a gypsum core between paper layers and can include foil backing for insulation and vapor control. Plaster itself is a composition, typically of lime or gypsum, water, and sand, which hardens when dry and is used to coat walls and ceilings. This technique has ancient origins, with evidence of plaster use dating back thousands of years in Egypt.13