(Right, far right) Some “new”
construction building materials have been around longer
than many of us have been
involved in the fire service. One
example of this is the simple
gusset plate, which was developed in the early 1950s.
NOT ALL ENGINEERED MATERIALS ARE BAD
Far too many in the fire service seem to take a
generalized approach with regard to engineered construction and subsequently view it all as one and the
same. For the most part, engineering has contributed
to far less mass in structural components, and this has
created legitimate concerns regarding their structural
integrity under fire conditions; however, this isn’t the
case for everything.
An example of this is glue laminated timber
(glulam). Glulam is manufactured using full dimen-
sion lumber, most commonly two inches by six
inches, and is laminated together using phenol-res-
orcinol, melamine-urea, melamine, or polyurethane
adhesives. The adhesive to lumber ratio in these mem-
bers is relatively low in comparison to many engi-
neered products. The resulting material is quite strong
with considerable mass, and it can withstand the
effects of direct flame contact for an extended amount
of time. Glulam is as close to traditional heavy timber
as we find in the engineered lumber classification, and
many fire departments rely heavily on these materi-
als as their route of travel and safe working platform
while operating topside. One caveat to this is that,
although glulam is very strong, it is still a combustible
material and ultimately contributes to the overall
fuel load of the structure. In addition to this, because
of the way that glulam is assembled using multiple
layers of dimensional lumber, tests have shown that
once one layer has completely burned away, there is
a brief period of renewed fire growth as a result of an
unburned surface that is now exposed.
Wood construction is not going anywhere. In fact,
we are seeing the industry flourish, especially with
the recent push for large mass timber high-rises using
cross laminated timber in many major cities. Wood is
a staple of the North American construction industry
and will always play a significant role in the profession of fighting fires.
MASS OVER MATH
When taking into consideration all the changes that
have occurred in the construction industry, one of the
most detrimental factors that affects us as firefighters
is the reduction of mass in our structural members.
For the most part, mass in structural components
increases the fire resistance qualities, which in turn
allows us more time to safely and effectively complete
our mission of saving lives and protecting property.
While engineering has brought many incredible
innovations to the construction industry, the use of
these engineering principles to reduce the size and
weight of structural members has overall contributed
to diminished working times inside or on top of a
building once the structural components have been
compromised by fire.
Another major contributing factor to mass reduction is the role of economics within the construction
(Above left, right) Glulam is manufactured using full dimension lumber and is laminated together using phenol-resorcinol, melamine-urea, melamine, or polyurethane adhesives. It is as close to traditional heavy timber as we find in the engineered lumber classification.