Red Seal Lather (Interior Systems Mechanic) Exam 2025 – 400 Free Practice Questions to Pass the Exam

The typical thickness of drywall used for interior walls is 1/2 inch. This thickness is commonly employed in residential construction because it strikes a balance between affordability, ease of handling, and effectiveness in providing a smooth surface for finishing. It is suitable for most interior applications, including walls and ceilings, where weight and space constraints are a consideration.

The other thicknesses listed are generally used in specific scenarios. For example, 1/4 inch drywall is often utilized for curved walls or as a veneer over existing surfaces, while 5/8 inch drywall is frequently used in commercial applications or in areas requiring additional fire resistance or soundproofing, such as shared walls in multi-family buildings. A thickness of 3/4 inch is not standard for interior wall applications and is rarely, if ever, used in typical drywall installations. Understanding these distinctions helps clarify why 1/2 inch is recognized as the standard choice for interior walls.