North Carolina Building Contractor License Practice Exam

What is the overall minimum thickness of stucco over concrete surfaces?

1. 1/2 inch

2. 3/4 inch

3. 1 inch

4. 12 inches

The correct answer is: 12 inches

The correct answer pertains to the established building codes and industry standards for applying stucco over concrete surfaces. Typically, the overall minimum thickness of stucco, which is often referred to in construction as a cement plaster system, is designed to be at least 3/4 inch or thicker for proper performance and durability. When stucco is applied, it comprises multiple coats: a scratch coat, a brown coat, and a finish coat. Proper layering ensures adhesion, water resistance, and structural integrity. A minimum thickness of 1/2 inch is generally considered insufficient for a durable external finish, as thinner applications are more prone to cracking and other failures due to temperature changes and other environmental factors. The values of 1 inch or 12 inches are excessive for standard applications. A stucco thickness significantly over 1 inch may lead to additional weight and potential structural issues, while 12 inches would be impractical and unnecessarily thick for a typical finish. The common standard maintains that a 3/4 inch total thickness strikes an ideal balance between durability and functionality, which is why this minimum thickness is often enforced in building codes and recommended by construction professionals. This ensures that the stucco performs adequately throughout its lifespan while adhering to safety and aesthetic considerations.