What type of building construction has the highest risk for fire spread?

Lightweight construction is recognized for having the highest risk for fire spread due to several key factors inherent to its materials and design. Most lightweight structures utilize engineered wood products, like trusses and I-joists, which are designed for strength and efficiency but tend to fail more rapidly in fire situations compared to heavier, solid materials.

In a fire, these lightweight materials can burn through or collapse quickly, creating a high risk of rapid fire spread within and beyond the structure. Additionally, the open spaces and architectural features common in lightweight construction can allow fire to travel more easily through the building, contributing to a faster overall spread.

In contrast, brick construction, while not immune to fire, has a much higher resistance to flame spread due to its non-combustible nature. Steel frame construction also offers superior fire resistance, provided that the steel elements are adequately insulated against heat. Wood frame construction, while more susceptible than brick or steel, does not generally reach the same level of risk associated with lightweight construction due to its thicker members. Thus, lightweight construction poses a significant risk in firefighting scenarios as it can fail quickly under fire conditions, making it vital for firefighters to understand how to effectively engage with this type of construction during an emergency.