What type of materials are primarily used in Type I construction as described by PD 1096?

Type I construction, as defined by the National Building Code of the Philippines (PD 1096), primarily involves the use of non-combustible materials, with steel being a principal component. Structures classified under Type I are designed to maintain fire resistance and structural integrity under high temperatures, which is where steel excels due to its strength and durability.

Steel frames are essential in Type I buildings because they provide necessary support while being able to withstand significant loads and fire exposure without compromising structural performance. This classification is important for high-rise buildings or structures that require enhanced safety measures against fire hazards.

The other materials mentioned, such as wood, are typically associated with less fire-resistant types of construction. While masonry can offer some fire resistance, it does not provide the same level of structural advantages and performance in tall buildings as steel does. The option of combining materials is also less relevant here, as Type I specifically emphasizes the use of non-combustible, primarily steel materials for construction.