Building Construction Flashcards

Which roof style is considered most dangerous for firefighters due to the potential for sudden, total collapse with little warning?

Answer: Bowstring truss roof

Bowstring truss roofs can collapse totally and suddenly when fire weakens the metal connections or truss members, giving firefighters virtually no warning before catastrophic failure.

What does 'fire load' (or fire loading) refer to in building construction?

Answer: The amount of combustible material present in a given area that can contribute to and sustain a fire

Fire load is the total quantity of combustible material in a space, often expressed in BTUs or pounds of wood equivalent per square foot, and determines the potential intensity and duration of a fire.

Why are masonry walls in Type III (ordinary) construction particularly dangerous to firefighters during a fire?

Answer: They can suddenly collapse outward during or after a fire without visible warning signs

Masonry walls lose structural integrity as mortar and wall ties weaken under prolonged heat exposure, and can collapse outward onto firefighters in a phenomenon sometimes called a 'curtain fall.'

What is a 'parapet wall'?

Answer: The portion of an exterior wall that extends above the roofline of a building

A parapet wall is the section of an exterior wall projecting above the roof level, and it poses a collapse hazard to firefighters operating on the roof or at the building perimeter.

How does platform frame construction differ from balloon frame construction in terms of fire behavior?

Answer: Each floor platform acts as a horizontal fire stop between stories, slowing vertical fire spread through wall cavities

In platform frame construction, the top plate and subfloor of each story interrupt the wall cavities, acting as built-in fire stops that slow vertical fire spread between floors.

During a structure fire, why are HVAC chases and utility shafts a significant concern for firefighters?

Answer: They act as chimneys, allowing fire and hot gases to travel rapidly between floors without detection

HVAC chases and utility shafts create vertical pathways that, through the chimney (stack) effect, allow fire, heat, and smoke to spread rapidly from floor to floor through otherwise uninvolved portions of a building.

Which type of building construction is historically known as 'mill construction' due to its widespread use in 19th-century textile factories?

Answer: Type IV (Heavy Timber)

Type IV (Heavy Timber), or 'mill construction,' uses large wood members that char slowly and resist sudden collapse, and was favored for factories where machinery vibration required robust framing.