Firewalls
Toronto fire ruins, 1904, view from Front
and Bay Street [ca. 1905] Photo William James
Tuesday, April 19, 1904 began like
many other days in downtown Toronto. The corner of King and Bay streets was a
developed business district. But the day would soon take a turn for the worst.
T. H. Johnson,
a night watchman employed by several downtown businesses, was making his rounds
when he smelled smoke. He spotted flames billowing out of the Currie
Building (today's Toronto Dominion Centre block) at Wellington and Bay. He ran
two blocks to reach the nearest alarm box. At 8:04
p.m., the alarm was sounded from Box 12, on the corner of King and Bay,
alerting the fire department to the worst fire the city of Toronto has ever
seen. Firefighters from as far away as Buffalo and New York joined in on the
battle, but despite valiant efforts, ninety buildings were destroyed, at an
estimated loss of $10 million. At that time, unemployment benefits and welfare
were not available and 5,000 people were suddenly without an income.
The Toronto fire of 1904 was a huge
disaster. It was probably one of the single most important events in Toronto’s history to have shaped the development of building codes and regulations as they
relate to fire safety in buildings. It was after this event that people
realized building standards had to be improved and enforced.
Here are the observations
made about buildings after the Toronto Fire.
- Buildings need to prevent the spread of
fire.
- Buildings need to withstand the effects
of fire for a long enough period of time to ensure that fire fighters can
get to the scene and contain the damage. Many buildings were destroyed
during the fire not by the flames but by other buildings falling beside or
near them.
- Buildings needed to provide an adequate
means for the occupants of a building to escape.
Since the Toronto fire of 1904, a number of
standards and rules have been created and are identified in the National Fire
Code of Canada and the National Building Code of Canada. Part 3 and Part 9 of
the Ontario building code contain the main requirements used by designers for
fire protection in and around buildings. Read 9.10 carefully. It can be
complicated and difficult to understand when one applies the requirements to a
specific building or site. Even today, industry professionals commonly make
mistakes or oversights when it comes to applying the rules and regulations of
Part 9 as it pertains to Fire protection.
OBC 9.10.11.1.(1) & (2) require that a
party wall located on a property line be constructed as a fire wall. The
exception to this requirement is a building of residential occupancy with no
dwelling unit above another dwelling unit. For instance a three storey single
family dwelling could construct a party wall on the property line that is NOT a
firewall. The party wall in this case would only need to be constructed with a
one hour rated fire separation.
If a firewall is required or if a firewall
is used it must be designed according to OBC 3.1.10. One of the requirements of
this Subsection is that the wall be constructed as masonry OBC 3.1.10.2.(3).
Following on with the initial overview and
analysis of a building in terms of Fire Protection and Construction
requirements, read OBC 9.10.14, Spatial Separations Between Buildings. This
analysis will yield pertinent information referring to the construction type of
‘exposing building faces' and the amount of windows allowed therein.
Figure 5 3 Storey Group C Building
- For the building showing above, determine
the minimum construction requirements for Wall ‘A’
- What is the maximum amount of window
openings that can be placed on the Wall A?
- What is the required FRR (Fire Resistance
Rating) of Wall A?
- Is combustible cladding (such as wood
siding) allowed on the exterior face?
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