UL: Analysis of Changing Residential Fire
Dynamics and its Implications on
Firefighter Operational Timeframes
timeframe for a legacy room to
transition to flashover was 29 minutes.
Synopsis
UL’s analysis examines the all-encompassing
effect from changes in residential environment
in terms of fire dynamics and the implications
for firefighter tactics. UL’s study examines the
impact of the modern residence on fire
dynamics and its impact on firefighting tactics.
The residential fire conditions that firefighters
arrive at today are very different than the
conditions faced several generations ago.
The steady change in residential
fire environment includes:

Demonstrated that the fire has
transitioned to flashover in most cases
prior to arrival of fire service or at the
very least crews will encounter a
ventilation limited fire.
Faster fire propagation

Modern window & interior doors fail
faster than legacy counterparts.

The change in modern dry wall linings
now allows for more content fires to
become structure fires. Fire penetrates
wall lining and fills the void and allows
for faster fire propagation.

Larger homes (increase in two story
homes)

Open home geometries (taller ceilings,
open floor plans, two story foyers, great
rooms)

Shorter times to collapse
Home Contents/Increased synthetic
fuel loads (plastics and textiles)

Modern home construction techniques
have removed components that had
prolonged collapse.

After unit arrival at eight minutes from
ignition, collapse is possible as soon as 1
minutes 30 seconds later; the legacy
room fire collapse hazard begins at 40
minutes after arrival.

New construction materials (engineered
products, green/sustainable items).
UL compared the changes in home contents and
construction materials through six experiments
contrasting modern and legacy living room
contents across three pairs of living room fires.
Then the findings from these experiments were
examined in the context of firefighting
operational timelines.
Takeaways
The six experiments revealed
that fire dynamics change rapidly
in today’s modern rooms
Shorter resident escape times

The impact of ventilation (flow paths) is
the key to the fire development in
structures

Fire departments must reexamine their
tactics to ensure they are still relevant
within this evolving fire environment
Read the Report
Faster flashover

Modern rooms had flashover occur in
less than five minutes, the shortest
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