Final answer:
Historically, construction begins with the foundation and proceeds upward, but advancements allow pre-assembled roofs to be hoisted by cranes. This is efficient and safe, especially for large or heavy materials.
Step-by-step explanation:
The question concerns whether roofs are usually pre-assembled on the platform and hoisted into place with a crane during construction. Traditionally, building a structure begins with the foundation, working systematically upwards until the highest level is reached
However, with the advancements in construction technology, parts of a building, including roofs, can be prefabricated using computer-aided machines. These prefabricated pieces are then transported to the construction site. Historical methods such as the Castello crane show that there has always been a need for mechanisms to hoist heavy materials. Today, the use of cranes and other lifting equipment can allow for pre-assembled sections, like roofs, to be efficiently positioned in place. In certain cases, especially when dealing with large spans or heavy materials, this approach can save time and enhance safety on-site.