Which type of construction resists failure in a fire much longer than other types?

The answer is Type IV construction, also known as heavy timber construction. This type of construction is characterized by the use of large, solid wood beams and columns that can withstand fire exposure for an extended period. The significant mass of heavy timbers provides a natural fire resistance due to the charring effect; when exposed to flames, the exterior of the wood will char, forming an insulating layer that protects the inner core of the timber. This charring slows down the rate at which the timber burns, allowing for a longer duration before structural failure occurs.

In contrast, other construction types do not offer the same level of fire resistance. Type I construction, although non-combustible, primarily consists of reinforced concrete and steel, which can still suffer from thermal expansion and weaken under extreme heat conditions. Type II construction is also non-combustible but often includes lighter materials that are more susceptible to failure during intense fires. Type III construction incorporates both combustible and non-combustible elements, which can lead to quicker fire spread and structural compromise.

Heavy timber construction is thus favored in scenarios where longevity and stability during a fire are critical, making it a preferred choice for certain types of buildings, such as those needing to accommodate long spans or large spaces.