Which class of construction involves masonry walls with non-combustible floors and roof?

The correct classification of construction that involves masonry walls with non-combustible floors and roof is Class 4. This classification specifically refers to buildings that primarily use non-combustible materials, which helps enhance their fire resistance. Masonry walls provide a sturdy structural element while giving significant fire protection, as they are less likely to burn compared to wood or other combustible materials. The non-combustible floors and roof further contribute to the overall safety and resilience of such buildings.

In the context of insurance and property classifications, understanding the structural components is crucial for assessing risk and coverage options. Class 4 buildings are often viewed more favorably by insurers because of their reduced fire risk compared to those built from combustible materials.