All exterior lath must be made of which material property?

All exterior lath must be made of which material property?

• A. Corrosion-resistant materials
• B. Non-metallic composites
• C. Copper and aluminum only
• D. Painted steel only

Answer: (A)

Exterior lath must endure weather and moisture over long periods, so it needs to resist corrosion. When the lath corrodes, it weakens the substrate for plaster, can cause cracks, rust stains, and bond failure. Therefore the material property required is corrosion resistance, ensuring the lath remains strong and stable in damp exterior conditions. This broad requirement covers multiple suitable materials—metals like galvanized steel, aluminum, or copper, and non-metallic options like fiber cement—so long as they resist deterioration. Painted steel isn’t inherently corrosion-resistant because its protection relies on the coating, which can wear away; copper and aluminum aren’t the only acceptable choices, since galvanised steel or other corrosion-resistant lath materials also meet the requirement.

Exterior lath must endure weather and moisture over long periods, so it needs to resist corrosion. When the lath corrodes, it weakens the substrate for plaster, can cause cracks, rust stains, and bond failure. Therefore the material property required is corrosion resistance, ensuring the lath remains strong and stable in damp exterior conditions. This broad requirement covers multiple suitable materials—metals like galvanized steel, aluminum, or copper, and non-metallic options like fiber cement—so long as they resist deterioration. Painted steel isn’t inherently corrosion-resistant because its protection relies on the coating, which can wear away; copper and aluminum aren’t the only acceptable choices, since galvanised steel or other corrosion-resistant lath materials also meet the requirement.