Type I construction provides the highest level of protection from fire spread because:

Type I construction is characterized by its use of non-combustible materials that have high fire-resistance ratings, which significantly enhances the building's ability to resist fire spread. This means that the structural members, including floors, walls, and columns, are typically made from concrete and steel, which do not ignite easily and can withstand high temperatures for extended periods without collapsing.

The high fire-resistance rating associated with the materials used in Type I construction is essential because it allows a building to maintain its structural integrity during a fire, thereby providing additional time for occupants to escape and for firefighters to control the blaze. This level of fire safety is particularly crucial in high-rise buildings and areas where fire safety regulations are stringent.

In contrast, other construction types, such as those that involve wood or materials with lower fire-resistance ratings, can easily contribute to the spread of flames and heat during a fire incident. Hence, the high fire-resistance materials used in Type I construction offer a significant advantage in preventing fire spread compared to constructions with combustible materials or lower ratings.