Red Seal Lather (Interior Systems Mechanic) Practice Exam

What is the standard thickness of drywall used for interior walls?

1. 5/8 inch

2. 3/4 inch

3. 1/2 inch

4. 1 inch

The correct answer is: 1/2 inch

The standard thickness of drywall commonly used for interior walls is 1/2 inch. This thickness strikes a balance between being lightweight and offering adequate strength for most residential applications. It is particularly suited for interior partitions, as it is easy to handle and install while providing sufficient sound absorption and fire resistance properties. In contrast, 5/8 inch drywall is typically used for specific applications where additional soundproofing or fire resistance is required, such as in commercial buildings or on ceilings. The other thicknesses, such as 3/4 inch and 1 inch, are not standard for typical interior wall construction; they are more commonly used in specialized applications or for structural elements, making them less practical for general wall installations in homes. This reinforces that 1/2 inch drywall is the go-to choice for most interior walls, aligning with industry practices.