What characteristic defines Class 1 construction?

Class 1 construction is defined by the characteristic that walls, floors, and roofs are constructed with wood. This classification indicates that the structure is primarily composed of materials that are more combustible compared to non-combustible alternatives. Typically, Class 1 buildings are lower in terms of fire resistance and are often seen in residential constructions or less fire-resistant commercial properties.

The other options refer to different classes of construction or materials. Non-combustible materials, for example, indicate a higher classification, likely encompassing fire-resistant buildings, while walls made of metal or masonry would show different structural properties not characteristic of Class 1. In essence, the defining trait of Class 1 construction lies in its reliance on wood, which influences aspects such as fire risk assessments and insurance evaluations.