Cellulose Fire Safety
Our industry hasn't always done a good job of explaining the fire resistance properties
of cellulose insulation. This has resulted in a general misunderstanding of the product
or lack of fully understanding its fire resistance benefits. Hundreds of thousands of
dollars have been spent on studies testing and proving the fire resistance of cellulose
insulation in structures. To those familiar with the product the results won't be
surprising but to those not familiar, they will be surprising.
Depending upon the manufacturer, cellulose insulation is approximately 85% processed
wastepaper and the balance is fire retardant chemicals. The Federal Government's
Consumer Product Safety Commission (CPSC) established the fire resistance properties
required for cellulose insulation. In addition, the building codes have put in place
required fire resistance properties depending upon the application. Cellulose insulation
is one of very few products with fire retardant chemicals as opposed to lumber,
sheathing, kraft-faced fiberglass batts, asphalt based roofing materials, carpet,
etc. that typically don't contain any fire treatments.
Because processed wastepaper is a material component, the initial assumption is
"we must be having more fire related problems with a paper based cellulose insulation
material". This is not true. The state of California conducted a study of 2 million
fires and concluded concerning fire and insulation materials:
There does not appear to be a significant number of attic fires related to any
particular manufacturer's product.
Heat-producing devices and electrical short circuits were major factors in
insulated-related fires. A study by Oklahoma City Fire Department found that
insulation-related fires paralleled market share of respective materials and
that the common denominator was recessed lighting fixtures, not insulation materials.
Government Sponsored Research
Extensive fire research associated with various building materials and construction has
been conducted by the research arm of the Canadian government
(National Research Council, NRC). This testing has been done in conjunction with many
major corporate sponsors such as Owens-Corning, Cellulose Insulation Manufacturers
Association, Boise Cascade, Gypsum Association, Louisiana-Pacific, Roxul Inc., and others.
A July 1994 report of 48 small-scale fire resistance tests by NRC found that fiberglass
had a "neutral effect on the fire resistance performance compared to a non-insulated
assembly" when using Type X gypsum board. When lightweight gypsum board is used, it
was found the fire resistance performance "was slightly lower than that of a
non-insulated assembly". It also found that "the installation of cellulose fibre in
the wall cavity provided an increase in the fire resistance performance of 22% to 55%
compared to a non-insulated assembly".
Additionally an April 1998 NRC report of various 32 full-scale floor assemblies concluded
very interesting results when varying the insulation material. Assemblies with solid wood
joists with a single layer of gypsum board ceiling determined that "glass fibre insulation
reduced the fire resistance by 20% while rock and cellulose fibre insulation increased the
fire resistance by 33% and 31 %, respectively, compared to a non-insulated assembly" For
wood I-joists, "cellulose fiber increased the fire resistance by 24% compared to a
non-insulated assembly". The following were detailed observations contained in the report.
"The glass fibre melted 2 to 3 min after the gypsum board fell off and was unable to
compensate for the earlier failure of the gypsum board."
"However the rock and cellulose fibre insulations remained in place after the gypsum
board fell off and were able to compensate for the earlier failure of the gypsum board
and protected the wood joists and subfloor for a substantial period."
No cellulose insulation tests were done on steel joists however "the installation of
glass fibre in the floor cavity reduced the fire resistance by 8% compared to a
non-insulated assembly". Based upon the results from the above wood joist configurations,
a logical assumption would be that cellulose insulation would increase the fire resistance
of steel joists construction.
Furthermore, a 2001 study by NRC of 14 full-scale steel stud walls found wall failure at
56 minutes for fiberglass, 59 minutes for rock fiber insulation, and 71 minutes for
Based upon studies, the International Building Code (IBC) acknowledged the fire resistance
benefits of cellulose insulation. The 2003 IBC allows cellulose insulation to contribute
an additive 15 minutes to the fire resistance of an uninsulated 2 x4 wood stud wall while
no additional minutes are allowed for standard fiberglass batts and foam insulation. These
provisions are contained in "Section 703: Fire Resistance Rating and Fire Tests".
The 2003 IBC further establishes fire resistance criteria for a product to be considered
as a fire stop in Section 712 and a fire block in Section 717. In both applications,
cellulose insulation testing meets the necessary criteria while typical fiberglass and
foam cannot be considered as either. This is the result of "ASTM E119 Fire Tests of
Building Materials and Construction" tests in 1999 and 2002 that exposed cellulose
insulation to temperatures exceeding 1600 F to ensure the fire endurance ratings of
the walls were meet or exceeded when insulated with cellulose insulation.
Tests conducted by Omega Point Laboratories in 1999 showed that cellulose insulation
can be used safely with electrical boxes as close as 3-1/2 inches to each other on
opposite sides in 2x4 fire-rated walls. The IBC accepts this with cellulose insulation
while requiring 24-inches of separation in fiberglass insulated walls.
The building codes establish a maximum flame spread of 25 and smoke generation index
of 450 for wall applications as tested under ASTM E84. Cellulose insulation will meet
this criteria in its installed form while paper faced fiberglass batts are permitted
to have the paper facing containing the asphalt-based adhesive removed to meet the
same fire performance criteria.
Paper-faced batts are not treated for fire resistance and are not covered by the same
stringent flammability standards that apply to cellulose insulation. For this reason
paper-faced batts, which are among the most commonly used forms of insulation in the
U.S., are no longer sold in Canada.
Consumer Product Safety Commission
The CPSC initially established the fire safety criteria of cellulose insulation. What
wasn't understood at the time was the criteria resulted in an insulation material
with superior fire resistance properties compared to fiberglass and foam insulation.
These fire resistance properties are contained in 16 CFR Part 1209 (1) of the Federal
Registry and must be complied with.
Full-Scale Fire Demonstrations
In 1978 the so-called "Big Burn" demonstration set fire to three structures; one
insulated with fiberglass, one with cellulose insulation, and one with no insulation.
The ceiling of the fiberglass insulated structure collapsed after 21 minutes while the
ceiling of the cellulose insulated structure collapsed after 70 minutes. In June 1998
GreenStone Industries at the Maryland Fire Training Academy observed similar results
in a demonstration burn.
According to Building Construction for Fire Suppression Forces, a publication of the
National Fire Services Training Academy: "It is critical to recall that noncombustible
does not mean 'safe'. And it certainly does not mean 'fireproof. The concept of
fire-resistance goes beyond that of noncombustibility. It refers to the capacity
of a material or construction to withstand fire or give protection from it, characterized
by its ability to confine a fire."
The fire retardants used in cellulose insulation result in the mass charring and remaining
in place longer than fiberglass or foam. This delays the time period in which flames will
reach the structural members or move through wall or floor cavities. This provides
increased protection and an increased opportunity to escape the structure.
Looking at the role you should want building materials and construction to play in giving
your family members a better opportunity to reach safety in the event of a fire, the above
references create a very convincing argument for using cellulose insulation.
Cellulose....it's naturally better insulation
The following pages contain all Cellulose Insulation fire related material.
R-TEK Insulation is your insulation contractor of choice.
If you have any questions regarding commercial or home insulation please do not hesitate
to call us at: (330) 753-8394. We will be more than happy to assist you.