ASD/LRFD Manual - American Wood Council

ASD/LRFD MANUAL FOR ENGINEERED Wood Construction
121
Structural Composite Lumber
Engineered wood products have fire resistive characteristics
very similar to conventional wood frame members.
Since many engineered wood products are proprietary,
they are usually recognized in a code evaluation report
published by an evaluation service. Each evaluation report
usually contains fire resistance information.
Very few elements of modern structures can be called
“fire proof.” Even in buildings where the major structural
members are noncombustible, most of the furnishings are
flammable. It is for this reason that much of the attention in
model building codes addresses issues related to containing
and limiting fires, rather than simply calling materials
combustible and noncombustible. The primary intent of
the building codes is to ensure structural stability to allow
exiting, evacuation, and fire fighting.
As with the previous topic of durability, this Manual
cannot cover the topic of designing for optimal structural
performance in fire conditions in detail. There are many
excellent texts on the topic, and designers are advised to
use this information early in the design process. To assist
the designer in understanding several ways in which fire
performance can be addressed, the following overview is
provided.
Fire sprinklers are probably the most effective method
to enhance fire resistance of engineered wood systems (as
well as other systems). They are designed to control the
fire while protecting the occupants and the building until
the fire department arrives. They are the ultimate way to
improve fire safety.
Heavy timber construction has proven to be acceptable
in many areas where fire safety is of utmost concern.
These applications have proven to be not only reliable, but
economical in certain structures – many wider width SCL
products can be used in heavy timber construction. Consult
manufacturer’s literature or code evaluation reports for
specific information.
The fire performance of wood structures can be enhanced
in the same ways as that of structures of steel,
concrete, or masonry:
• Fire sprinkler systems have proven to be effective
in a variety of structures, both large and small
• Protection of the structural members with materials
such as properly attached gypsum sheathing can
provide greatly improved fire performance. Fire
ratings, as established from test procedures specified
in ASTM E-119, of up to 2 hours can be achieved
through the use of gypsum sheathing
• Where surface burning characteristics are critical,
fire-retardant treatments can be used to reduce the
flamespread for some products
To reiterate, this Manual does not purport to address
this topic in an all-inclusive manner – it is merely an
attempt to alert designers to the need to address fire performance
issues in the design of the structure.
M16: FIRE DESIGN
16
American Forest & paper association