Which lath type is typically installed after weather protection is in place?

Which lath type is typically installed after weather protection is in place?

• A. Conerite lath
• B. Gypsum lath
• C. Wire-fabric lath
• D. Perforated gypsum lath

Answer: (A)

When exterior plaster is going over a weather-protected wall, you want a base that can withstand moisture and provide a rigid, solid substrate for the plaster to key to. Conerite lath is a cementitious, fiber-reinforced lath designed for this purpose. It bonds well with plaster and remains stiff and stable even with exposure to weather, which is why it’s installed after the weather protection is in place. Gypsum lath and perforated gypsum lath are gypsum-based and are more prone to moisture damage, so they’re used in interior or well-protected spaces rather than on exterior surfaces. Wire-fabric lath is a metal mesh that can support plaster, but it doesn’t offer the same rigid, moisture-resilient base as cementitious lath, making it less ideal for exterior applications once weather protection is needed.

When exterior plaster is going over a weather-protected wall, you want a base that can withstand moisture and provide a rigid, solid substrate for the plaster to key to. Conerite lath is a cementitious, fiber-reinforced lath designed for this purpose. It bonds well with plaster and remains stiff and stable even with exposure to weather, which is why it’s installed after the weather protection is in place.

Gypsum lath and perforated gypsum lath are gypsum-based and are more prone to moisture damage, so they’re used in interior or well-protected spaces rather than on exterior surfaces. Wire-fabric lath is a metal mesh that can support plaster, but it doesn’t offer the same rigid, moisture-resilient base as cementitious lath, making it less ideal for exterior applications once weather protection is needed.