At the start of the 20th century, new multistory buildings made of steel and concrete were known as what?

At the start of the 20th century, new multistory buildings constructed from steel and concrete were categorized as Class A buildings. This classification was significant because the materials used in these structures contributed to their resistance to fire, providing improved safety in urban environments. Class A buildings were typically designed with non-combustible materials, making them less vulnerable to fire damage compared to other construction classes that used more flammable materials.

The rise of Class A buildings marked a shift in architectural design and urban development, influencing fire prevention and safety measures. Their robust construction facilitated the growth of cities, accommodating more inhabitants and businesses within smaller footprints. Understanding this classification helps comprehend the evolution of building codes and fire safety practices that emerged in response to urban growth and the risks associated with high-rise structures.