2009 Issue 3
Structural Stability of Engineered
Lumber in Fire Conditions
Results of UL research study
In 2008, Underwriters Laboratories ®
­ onducted a fire research study sponsored
c
by the Federal Emergency Management
Agency’s Assistance to Firefighters Fire
Prevention and Safety Grant Program in
partnership with the Chicago Fire Department, International Association of Fire
Chiefs and Michigan State University.
The research was conducted to enhance
In this issue:
2 What’s
Hot
by Bob Backstrom and Mahmood Tabaddor, Ph.D.
understanding of hazards to firefighters
posed by use of lightweight wood trusses
and engineered lumber in roof and floor
designs that are increasingly replacing
conventional solid joist construction in
residential structures. The project investigated and compared the fire performance
of conventional solid joist lumber and
lightweight lumber used in floor and
7 Questions
& Answers
roof construction when subjected to fire
tests. The fire performance data allow fire
professionals to better understand fire
hazards and assess safety risk to building
occupants and firefighters. And, this information provides substantiation for code
requirements for fire ratings of lightweight
(continued on page 4)
Corner:
3 Canadian
New Residential Detector
Regulations in Canada
8 Calender
of Events
The Fire & Security Authority
UL
2009 Issue 3
www.ul.com/fsa
What’s Hot…
UL-sponsored symposium
to focus on residential
fire safety
UL is committed to life safety and public
education that make the world a safer
place to live and work. In support of this
goal, UL and the Phoenix Fire Department
are co-sponsoring a two-day educational
symposium focused on sharing ideas and
fostering discussion among attendees
about fire safety in North American
residential buildings. Participants will
learn how they can support fire safety
initiatives in residential home construction
by designing, specifying and building lowcost fire safety building components into
residential buildings. The symposium will be
held December 2-3 in Phoenix, AZ.
Questions & Answers
Does UL offer any training
or education courses for
fire safety professionals or
building code officials?
For over 100 years UL has provided
technical expertise to manufacturers
and safety stakeholders. Through a
combination of online training, books,
safety videos, live Web-delivered programs
and facilitated workshops, UL University
offers training solutions customized to
To learn more and to register, please
go to www.uluniversity.us, select Fire
Safety and the Designing Fire Safety into
Residential Construction: Perspectives,
Ideas and Trends course.
Fire & Building
Materials Conference
UL is pleased to announce it will be playing
a major role in Principia Partners’ Fire 2009:
Flammability and Combustibility in Building
Materials Conference. The conference will
be at the Chicago Marriott Downtown,
Chicago, IL on November 16 & 17.
Chris Hasbrook, UL’s Vice President and
General Manager, and Robert Backstrom,
UL Senior Staff Engineer, will be speaking.
UL is also the full program sponsor for
the event and will be hosting a tour of
its facilities with a live fire test during the
afternoon of November 17.
This is a unique conference that specifically
focuses on the latest developments in
fit your needs. Below are two of UL’s
featured courses for the fire and regulatory
community.
Structural Stability of Engineer
Lumbered in Fire Conditions is a
complimentary two-hour presentation
that summarizes a research study on the
hazards posed to fire fighters by the use of
lightweight construction and engineered
lumber in floor and roof designs. For more
information and to register for this course
at no cost, please visit www.uluniversity.
us/catalog/display.resource.
aspx?resourceid=187716.
Performance of Special Extinguishing
Agents for Firefighter Use is a
complimentary one-hour presentation
based on a research study evaluating
02
building materials and their performance
in the fire environment, including how
current and future trends in fire codes,
building design, raw material technologies,
and building materials will affect the
building products industry. The entire
program is on Principia’s website at
www.PrincipiaConferences.com.
Principia is also offering a special 40%
discount off of the registration fee for all
UL clients and safety stakeholders, simply
write the code “UL-special” adjacent to
your name on the on-line registration form.
If you are interested in the tour, please call
Principia to reserve your space as seating
is limited.
For more information, please
contact Robert Tockarshewsky
with UL at +1.631.546.2202 or at
[email protected];
or Steve Van Kouteren, with Principia
Partners at +1.505.466.3749 or at
[email protected].
the performance and effectiveness
of special extinguishment agents in
residential firefighting. This presentation
examines the fire performance of various
special agents including wetting agents
and Class A foams and compares
their performance to that of a baseline,
traditional water application. For more
information and to register for this course
at no cost, please visit www.uluniversity.
us/catalog/display.resource.
aspx?resourceid=188205.
For information about the rest of
UL’s training catalog, please visit
www.uluniversity.com for a
complete list of courses.
The Fire & Security Authority
Canadian Corner
UL
2009 Issue 3
03
New Residential Detector
Regulations in Canada
In 2007, Health Canada (HC) launched a consultation process to
provide the public with an opportunity to review a proposal to, among
other things, update the health and safety requirements for residential
detectors covered under the Hazardous Products Act (HPA).
The HPA grants the authority to HC to
prohibit or restrict the advertisement, sale
or import of products that are or are likely
to be hazardous to the public.
Underwriters Laboratories of Canada
actively participated in this process. And,
as a result of the public consultation
process, several significant changes were
made to the HC regulations relating to
smoke detectors, smoke alarms, audible
signaling devices and control units.
Consultation process
As explained in HC’s consultation process,
the requirements for residential detectors
under the HPA are intended to ensure that
the products available to the Canadian
market facilitate and complement the
National Building Code (NBC) and National
Fire Code (NFC). However, the consultation
process revealed an important gap: the
NBC and NFC can only regulate products
used in buildings. These codes cannot
regulate the import, advertising and sales
of these same products.
Regulating these products under the
HPA minimizes the potential for buying
and installing sub-standard products
as it is illegal to import, advertise or sell
such noncompliant products in Canada.
Only those products that meet the CAN/
ULC or ULC Standards will be available to
consumers. The impact extends beyond
building construction that would be normally
be inspected to determine detectors are in
compliance with the standards referenced
in the NBC and NFC. In many cases,
consumers simply buy individual detectors
to replace or supplement the ones already
installed in their homes. With the products
regulated under the HPA at the consumer
level, they too would be assured that the
products available in Canada also meet
the current CAN/ULC or ULC Standards.
By regulating residential detectors under
the HPA, HC provides the legal basis to
close this gap and ensure that Canadians
enjoy the benefits of the latest in alarm and
detector technology.
(continued on page 7)
The Fire & Security Authority
UL
2009 Issue 3
04
Engineered Lumber in Fire Conditions (continued from cover)
construction in residential structures to
further enhance firefighter safety. The tests
were conducted at UL’s Northbrook, Ill.,
fire test laboratory during 2008.
Background on the UL research project
For more than 35 years, the fire service
community has repeatedly expressed
concern regarding the structural
performance of wood “I” beams and wood
trusses commonly known as lightweight
wood construction during a fire. In
October 1992, the National Fire Protection
Research Foundation published a report
titled, “National Engineered Lightweight
Construction Fire Research Project —
Technical Report: Literature Search &
Technical Analysis.” The report cited 60
articles published between 1970 and
1990 related to the fire performance of
lightweight wood construction. The report
identified the need for fire performance
data and training focusing upon the
fire performance of lightweight wood
construction. These needs remain today
and have been amplified by incident
reports collected by the National Fire
Fighter Near-Miss Reporting System and
National Institute for Occupational Health
(NIOSH) Fire Fighter Fatality Investigation
and Prevention Program.
Because of concern for fire fighter safety
and misinformation out in the field, UL
approached the Federal Emergency
Management Agency to offer assistance.
Because no standardized tests had
been conducted to compare traditional
to modern assemblies, UL considered it
important to develop a comprehensive
test plan to research the fire performance
of assemblies representative of typical
residential construction, the different
materials within floor assemblies and
various other factors. In addition, the result
from such research was to be developed
into a fire fighter training program.
UL test plan
The test plan called for nine fire tests:
seven floor-ceiling assemblies and two
roof-ceiling assemblies. A goal of the
project was to develop comparable fire
performance data among assemblies. All
assemblies were intended to represent
typical residential construction, with
some assemblies representing legacy
construction methods and materials and
others representing modern methods and
Photograph of mannequins representing standing and
crawling fire fighters
materials including lighter weight wood
structural members. Two of the assemblies
did not include a ceiling; six of the
assemblies included a ceiling consisting
of ½ inch regular gypsum board; and one
assembly included a ¾ inch plaster ceiling.
Standard ASTM E119, Fire Tests of
Building and Construction Materials,
describes a fire test method that
establishes benchmark fire resistance
performance between different types
Table 1 — Description of Test Samples
Test Assembly
Supports
Ceiling
Floor or Roof
1
2 inch x 10 inch with 16-inch centers
None
1 inch x 6 inch subfloor and 1 inch by
4 inch finish floor
2
12 inch deep “I” joist with 24-inch centers
None
23/32 inch OSB subfloor, carpet padding
and carpet
3
2 inch x 10 inch with 16-inch centers
½ inch regular gypsum wallboard
1 inch x 6 inch subfloor and 1 inch x
4 inch finish floor
4
12 inch deep “I” joist with 24-inch centers
½ inch regular gypsum wallboard
23/32 inch OSB subfloor, carpet padding
and carpet
5
14-inch parallel chord truss with steel gusset
plate connections with 24-inch centers
½ inch regular gypsum wallboard
23/32 inch OSB subfloor, carpet padding
and carpet
6
14-inch parallel chord truss with glued
connections with 24-inch centers
½ inch regular gypsum wallboard
23/32 inch OSB subfloor, carpet padding
and carpet
7
2 inch x 6 inch with 16-inch centers and 2/12 pitch
½ inch regular gypsum wallboard
1 inch by 6 inch roof deck covered with
asphalt shingles
8
2 inch x 10 inch with 16-inch centers
¾ inch plaster
1 inch by 6 subfloor inch and 1 inch by
4 inch finish floor
9
Roof truss with steel gusset plate connections
with 24-inch centers and 2/12 pitch
½ inch regular gypsum wallboard
7/16 inch OSB covered with asphalt shingles
The Fire & Security Authority
Images from video recordings of each experiment
of building assemblies. For floor-ceiling
and roof-ceiling assemblies exposed to a
standardized fire, the standard requires
that a minimum 180 square foot sample
prohibit the passage of flame and limit the
temperature rise at specific locations while
supporting a load. The standardized fire
represents a fully developed fire within a
residential or commercial structure with
temperatures reaching 1,000ºF at five
minutes and 1,700ºF at 60 minutes.
UL
The nine fire tests conducted by UL
complied with the requirements of ASTM
E119, but the applied structural load was
nontraditional. Typically, a uniform load
is applied on a floor or roof to fully stress
supporting structural members. This load
is generally higher than the minimum
design load of 40 pounds per square foot
(psf), as specified by the building code
for residential construction. For the UL
fire tests, the sample load was intended
to represent typical conditions during a
fire. A load of 40 psf was placed along
two of the four edges of the floor-ceiling
assemblies to represent loads on the
perimeter of a room. On each sample, two
300-pound mannequins simulating fire
service personnel were placed near the
center of the sample. For the two samples
that represented roof-ceiling assemblies,
the two mannequins were the only live
load applied on the test sample. Table 1
summarizes the construction details of
each test sample.
Test results
The results of the ASTM E119 fire tests
are expressed in terms of hours such
as ½ hour-, 1 hour- or 2 hour-rated
2009 Issue 3
05
assemblies. Because all fires are different
with respect to room size, combustible
content and ventilation, these time ratings
are not intended to convey the actual
time a specific structure will withstand a
fire. Instead, the ASTM E119 test method
provides a benchmark that enables a
comparison of fire performance between
test samples.
For unrestrained floor-ceiling assemblies
and unrestrained roof-ceiling assemblies
such as the tested samples, ASTM E119
includes the following conditions of
acceptance:
• The sample shall support the applied
load without developing conditions that
would result in flaming of cotton waste
place on the floor or roof surface
• Any temperature measured on the
surface of the floor or roof shall not
increase more than 325ºF and the
average temperature measured on the
surface of the floor or roof shall not
increase more than 250ºF
(continued on page 6)
Table 2 — Summary of Test Results to ASTM E119
Test Assembly
Time of 250ºF average
temperature rise on surface
of floor/roof (in minutes)
Time of 325ºF maximum
temperature rise on surface
of floor/roof (in minutes)
Flame passage through
floor/roof (in minutes)
Collapse
(in minutes)
Fire Resistance
Rating (min)
1
*
*
18:30
18:45
19
2
*
*
06:00
06:03
6
3
*
*
44:15
44:45
44
4
*
*
*
26:45
27
5
*
29:15
28:40
29:15
29
6
*
24:15
26:00
26:45
24
7
39:45
38:30
26:00
40:00
26
8
*
*
*
79:45
51**
9
*
*
*
23:15
23
* This condition was not achieved during the fire test.
** Plaster ceiling in contact with furnace thermocouples at 51 minutes. The test method requires that the junction of the thermocouples
in the furnace be placed 12 inches from the ceiling surface at the beginning of the test and shall not touch the sample as a result of deflection.
The Fire & Security Authority
UL
2009 Issue 3
06
Engineered Lumber in Fire Conditions (continued from page 5)
The results of the nine fire tests in terms of
the ASTM E119 conditions of acceptance
are summarized in Table 2.
The objective of this research project
was to develop fire endurance data
on assemblies to compare the fire
performance of legacy construction
(dimensional sawn cut lumber, solid
sub- and finish flooring) to that of modern
protected and unprotected lightweight
construction (engineering structural
elements, oriented strand board subfloor
and carpeted finish flooring). One insightful
comparison is that of time to collapse:
• The unprotected legacy construction
(assembly 1) collapsed at approximately
19 minutes as compared to six
Finite element model of assembly 2 illustrating
the mechanical loads
Temperature result comparison between model
and test for assembly 1
Temperature contour of cross section for
assembly 2 at three minutes
minutes for the unprotected lightweight
construction (assembly 2)
• Adding a non-fire rated, generic ½ inch
thick gypsum board increased the time
to collapse for legacy construction
(assembly 3) to 44 minutes, an
improvement of 25 minutes
• For modern construction (assembly
4), the installation of ½ inch gypsum
wallboard increased the time to collapse
to approximately 27 minutes, an
improvement of 21 minutes
Of particular interest is the time to collapse
of very familiar traditional construction,
dimensional sawn cut lumber protected by a
metal lath / plaster ceiling (assembly 8). This
assembly demonstrated the longest time —
nearly 80 minutes — to structural collapse.
Computational modeling
Computational modeling of the
fire response of building materials,
components and systems is gaining
ground due to advances in analysis
techniques and computing technology.
As part of this project, UL studied the
challenges of using computational
modeling tools to simulate the fire
performance of wood-based components.
Using the commercial finite element (FE)
software ANSYS©, sequentially coupled
thermal and mechanical analyses were
conducted for two unprotected floor
assemblies: a conventional wood floor
(Assembly 1) and an engineered wood
floor (Assembly 2). The main challenge in
modeling wood floors as opposed to other
common building materials such as steel,
concrete and masonry is that wood burns
and chars. As such, any model predicting
performance of wood-based structural
systems must account for this behavior.
The FE models of the floor assemblies
were built based on detailed construction
drawings and included all relevant
boundary and loading conditions of
the floor furnace test. However, a very
critical input to the FE models was the
thermal and mechanical properties for the
constituent materials. In a fire environment,
construction elements are exposed
to a very wide temperature range that
reaches high temperatures. Over this wide
range, wood degrades and decomposes
significantly, changing material properties
such as thermal conductivity, modulus of
elasticity, etc. So it is important to have
material property data for the different
wood components over the entire
temperature range of interest. As such,
these properties will also include wood
in its charred state. The input material
properties for both the thermal and
mechanical analyses were measured from
wood samples of the two floor assemblies
by Michigan State University under the
direction of Dr. V. Kodur.
Thermal results for the model were
computed using a transient analysis
that included radiation, convection and
conduction modes of heat transfer. For
structural results, a nonlinear, quasi-static
elastic analysis was performed at select
points in time.
For the thermal model, comparison with
thermocouple measurements pointed to
the importance of adding internal heat
generation elements to simulate the actual
burning of wood and accurate measure of
temperature dependent material properties
of the wood and the char. Though the
model did not accurately predict the final
deflection magnitudes, the structural
model did predict that floor assembly 2
would lose structural stiffness at a much
faster rate than floor assembly 1. By
designing and conducting tests similar to
those described in this article and building
test databases, UL is continuing research
on improving the predictive capabilities
of computer models for wood burning
building components and systems.
Getting the word out to the fire service
To get the word out to the fire service,
UL made numerous presentations at
symposia sponsored by fire house and
fire protection engineering trade media;
the 2008 Chicago Fire Department’s
Strategy & Tactics Conference and Expo;
UL’s 2008 Global Fire Service Leadership
Conference; the Georgia Fire Chiefs
Association meeting; and the Colorado
Fire Marshals and ICC Code training
The Fire & Security Authority
UL
2009 Issue 3
07
symposia, 2009 NFPA Conference & Expo,
FIRE 2009 Flammability & Combustibility
in Building Materials Conference, and
the 2009 IAFC Fire Rescue International
Conference. The January/February 2009
issue of the International Fire Fighter
distributed to more than 370,000 U.S.
and Canadian fire fighters highlighted the
research. UL’s research was covered by
WISN-TV in Milwaukee.
A free web-based training program for
the fire service providing a summary of
the tests and lessons learned is available
on UL’s Web site at www.ul.com/
ltwtconstruction.
For more information on this
project, please contact Bob
Backstrom at +1.847.664.2250 or
at [email protected].
For a full report on the first
phase modeling of the wood floor
assemblies, please contact Mahmood
Tabaddor, Ph.D at +1.248.705.4378
or at [email protected].
Detector Regulations in Canada (continued from page 3)
In the consultation process, several
options for updating the HPA were
presented. They were:
1.Take no action, which would have
effectively resulted in industry
manufacturing in compliance with ULC,
NBC and NFC current state-of-the-art
requirements, while HC would continue
requiring compliance with outdated
1970s era standards
2.Adopt standards other than those
in the proposed regulations that
would have resulted in significant
incremental costs for HCs with little
incremental benefit
3.Adopt the proposed regulations
referring to current ULC Standards as
amended periodically. This was viewed
as the most efficient option for the
government of Canada to pursue as
the ULC Standards development
process includes extensive
consultations with stakeholders
including manufacturers and HC.
The process also provides advance
notice and time for manufacturers to
adjust production specifications to
bring their products into conformity
with the newer standards
The decision was to utilize option 3 that
resulted in the creation of Residential
Detectors Regulations referencing ULC
Standards. This was deemed the best
option for getting the most modern
and safest detectors/alarm systems
meeting ULC Standards into the hands of
consumers.
During its consultation process, HC gave
a strong endorsement to the national
standards system that is administered
by the Standards Council of Canada
as well as Underwriters Laboratories of
Canada as a Standards Development
Organization and a Certification and
Testing Organization.
The new regulations
The Residential Detectors Regulations
pursuant to Section 5 of the HPA
came into effect on June 18, 2009.
These federal regulations allow for the
continuous reference to ULC Standards as
amended from time to time and that any
required text for products covered by the
regulations be published in French and
English.
Compliance with these regulations will
be monitored by ongoing Health Canada
inspection programs.
For more information on these new
regulations, please contact Brian McBain,
Regulatory Services, at +1.418.844.0063
or at [email protected] or Rae
Dulmage at +1.613.755.2729, ext. 6229
or at [email protected].
Non-Profit Org.
U.S. Postage
PA ID
Permit No. 1009
Northbrook, IL
333 Pfingsten Road
Northbrook, IL 60062-2096
United States of America
The Fire & Security Authority
UL
2009 Issue 3
www.ul.com/fsa
08
Calendar of Events
If you would like The Fire
& Security Authority to
consider publishing your
upcoming events, contact
Kim Delort, editor, in
Northbrook, IL, by e-mail at
[email protected]
Please type “Calendar” in the
subject line.
October 14–18
American Fire Sprinkler
Association Annual
Convention (AFSA)
San Diego, CA
www.firesprinkler.org
October 16–19
China Fire 2009
National Agricultural Exhibition
Hall, Beijing, China
www.fireexpo.cn/index.php
October 21–22
Security Canada Central
Toronto, ON, Canada
www.securitycanadaexpo.com
October 29–30
International Security
Conference 2009 (ISC East)
New York, New York
www.isceast.com
October 29–31
IFSEC, India
Pragati Maidan, New Delhi
www.ifsecindia.com
The Fire & Security Authority ®
Published by the Regulatory
Services Department and the
Building Materials/Life Safety and Security
Industries of Underwriters Laboratories Inc.
A Nationally Recognized Testing Laboratory (NRTL)
Managing Editor
Kim Delort
T:: +1.847.664.3606
E:: [email protected]
November 1–4
Security China
Exposition 2009
Shenzhen, China
www.cpse.com.cn/CN/About/
News.aspx
November 4–6
International Sleep
Products Association
(ISPA) Industry Conference
and Exhibition
Bonita Springs, FL
www.sleepproducts.org
November 4–6
India SCCP Workshop
Theme: Fire Safety In Tall
Buildings
New Delhi, India
November 16–17
Fire 2009, Flammability
and Combustibility in
Building Materials
Chicago, IL
www.principiaconferences.
com
December 2–4
Construct Canada
Toronto, ON, Canada
www.constructcanada.com
December 2–3
Residential Fire Safety
Symposium
Phoenix, AZ
www.uluniversity.us
UL Hosted Event
Address changes and additions
T:: +1.847.664.2461
F:: +1.847.509.6257
E:: [email protected]
© 2009. All rights reserved. BDI 09XXXX