Stucco is a type of finish material made of lime, sand, and water. Builders apply this thick, paste-like mixture to walls and ceilings using a trowel, and the stucco eventually dries to form a hard, cement-like finish. Because wet stucco offers little structural stability, builders often apply this material across a support frame called a stucco lath. Stucco lath also helps to thicken the layers of a stucco wall to create a more stable, long-lasting construction.
To understand how a stucco lath works, it's helpful to understand how wood-frame construction works. Builders install vertical units of lumber at specified intervals along the floor to create a wall. The gaps between these framing members are typically large enough to allow a person to walk through, making them incapable of supporting stucco. By adding thin strips of scrap lumber perpendicular to the framing members, builders create a stucco lath to support the stucco as it dries.
Many older homes feature a wooden stucco lath on either the interior or exterior side walls of the home. These wood laths are subject to some problems that have led builders to consider alternate stucco lath materials. Wooden laths expand and contract over time, leading to potential cracks and damage in the stucco, or in the framing itself. They may also rot or wear over time due to moisture or pests. Wooden stucco lath also takes a great deal of time to install, and increases the cost and duration of stucco installation.
Because of these potential problems, modern installers typically use steel stucco lath rather than traditional wooden versions. Metal lath consists of a heavy-duty chicken wire mesh that can be nailed or stapled to wood framing or even some types of masonry. These metal laths can also be bent and shaped to form complex designs and intricate shapes. This allows builders to create unusual ceiling and wall configurations, such as those found in themed buildings or theaters.
Compared to wooden stucco lath, metal versions help to reduce the cost of stucco installation and allow builders to complete projects more quickly. Builders can choose from several types of metal lath products depending on the application. Standard versions feature woven or expanded construction, while more advanced models may be welded for extra strength and durability. For lightweight stucco projects, fiberglass lath may be sufficient to support the stucco as it dries.