Rigid polyurethane or polyisocyanurate foams 

are effective insulation materials for the construction

industry(1). Depending on the chemical formulation

and other product composition factors, combustibility

characteristics of polyurethane or polyisocyanurate

foams vary widely, as do those of other organic

materials. 

All organic foam insulations, regardless of whether

they contain fire retardants, should be considered

combustible and handled accordingly. Certain precautions must be taken to minimize any potential for

fire through accidental ignition in handling, storage,

and use. How polyurethane or polyisocyanurate foams

are used in a building ultimately determines their

fire safety. In many cases, type of occupancy and

type of construction also may require the addition

of sprinkler protection and/or smoke detectors.

The model building codes require that all foam

insulation be separated from the interior of a building by an approved thermal barrier such as 1

⁄2-inch 

gypsum wallboard. Under specific conditions, such

as those discussed in this bulletin, this requirement

may be waived. The model building codes provide

for evaluation of the fire performance of new or

improved products and systems of building construction through the use of “diversified” testing such

as ANSI/UL 1256, FM 4450, UBC Standard 26-3,

and FM 4880 fire tests. Thus, some poly

and polyisocyanurate foam insulations a

have earned various building code acce

certain applications without a thermal b

these fire tests. Examples include (1) poly

roof insulation and spray polyurethane f

systems directly applied to steel roof de

metal-faced polyurethane and polyisocy

laminate panel products, and (3) some p

foam sealant applications. Always chec

building codes for local area requiremen

the manufacturer for further information 

specific code acceptance.

& Combustibility .............................

Fire Safety During Construction ........

Storage...................................

Application.............................

Disposal .................................

Fire Safety in Design .......................

Interior Applications ...............

Exterior Applications ...............

Combustibility Tests, Ratings, and Ha

Additional Information ....................

(1) For information about the performance features and applications of commercially available polyurethane and polyisocy

insulation products, consult the following publication by the Alliance for the Polyurethanes Industry: Polyurethane and 

Foams: Inch for Inch One of the Most Efficient Insulators (AX106).
at the construction site.

Storage

• Store drums of liquid materials within temperature 

and environmental conditions recommended by 

the material manufacturer.

• Store foam boardstock in limited quantities, in an 

accessible location, and free from ignition hazards. 

• Consult your insurer and local fire officials for 

specific recommendations.

Application

Insulation contractors should observe the following

recommendations:

• When opening drums of either resin or 

diisocyanate, first loosen the bung two turns 

to allow vapor pressure relief. 

• Foamed-on-site polyurethane chemicals should be

mixed and applied only by applicators trained in 

their proper use and familiar with their limitations. 

Foam chemicals should be handled and applied

according to system manufacturer/supplier

recommendations.

• Provide adequate fire alert and fire extinguishing 

equipment at the installation site. Water in a fine 

spray is an effective method for extinguishing 

rigid polyurethane or polyisocyanurate foam fires; 

1910.252. Trades performing hot work a

to observe the following restrictions:

• No open flames, cutting and welding 

intensity heat sources, and smoking m

permitted in storage and application a

• If “hot work” must be done within 35 

bustible materials, including exposed 

or polyisocyanurate foams, (1) it must 

from heat and sparks by an acceptab

tant barrier, and (2) a fire watch shoul

• No welding or cutting metal is permitt

with these foams.

Disposal

• Do not mix liquid waste components 

disposal convenience. Mixed “A” and 

nents can create pressure within clos

causing rupture or explosion. Conditio

could exist for spontaneous combust

improperly mixing “A” and “B” compo

• Prior to storage, residues in empty dr

be neutralized to prevent rupture or e

closed containers. For example, ruptu

sion might happen if water entered an 

drum that then was sealed. (Refer to 

Division/SPI Technical Bulletin AX151, 

the Responsible Disposal of Container

from Polyurethane Raw Materials Proc

2

(2) The Polyurethane Division/The Society of the Plastics Industry, Inc. is the predecessor organization of the Alliance for t

Polyurethanes Industry (API), a Business Unit of the American Plastics Council. As such, these Technical Bulletins can 

obtained by contacting API.
3

code officials, insurers, and manufacturers’ specifications and installation instructions must be consulted

in each specific instance of product application, system design, and building occupancy. For example,

most applications will require the use of a suitable

thermal barrier covering the interior-exposed surface

of polyurethane or polyisocyanurate foam insulation;

some products and applications as a result of testing

may not require thermal barriers. Additionally, certain

applications and occupancies may require sprinkler

protection and/or smoke detectors. 

The following are some fire safety design guides for

consideration by the architect and contractor based

on building codes, as well as recommendations of the

Alliance for the Polyurethanes Industry (API).

Interior Applications

• Effective thermal insulation, as provided by 

polyurethane and polyisocyanurate foams, can 

result in rapid heat buildup if a fire should occur. 

The improper use of polyurethane or polyisocyanurate foam insulation, in conjunction with other 

combustible materials in and within the building 

structure, may contribute to the rapid spread of 

fire. Thermal insulation should only be used and 

installed in strict accordance with manufacturer/

supplier recommendations and local building 

codes, as well as insurance carrier considerations.

• Unless otherwise approved by authorities having 

jurisdiction, polyurethane or polyisocyanurate 

foams used in interior wall and/or ceiling construc

cores, the model building codes spec

thickness for steel (0.016") or aluminu

facings and maximum flame spread a

ratings for the foam cores. The codes 

require automatic sprinklers. Some m

polyurethane or polyisocyanurate-lam

have earned various building code an

approvals as exceptions to these requ

based on results of acceptable divers

provisions of the codes. Also, in certa

codes, walk-in coolers or freezers of l

400-square-foot area are considered 

do not require sprinklers.

• Fire blocks may be required in the de

warehouse ceiling areas, between floo

multi-story building, in certain concea

and at penetrations into pipe chases 

tion shafts. Consult local building cod

specific requirements.

• Polyurethane or polyisocyanurate foa

not be used in areas immediately adja

above combustion equipment (such a

and chimneys), high temperature proc

ment or piping (unless specifically des

such application), or in other locations 

subject the foam insulation to temper

exceeding manufacturer/supplier recom

• Polyurethane or polyisocyanurate foa

used to fill cavities within masonry wa

grade-level concrete floors. Consult m

and suppliers of specific foam insulat
4

used as a roof covering over concrete, poured 

gypsum, tongue and groove planking, plywood, 

dimensional lumber or other properly prepared roof

decks if the foam insulation is part of a Class A, B,

or C roof covering per ASTM E-108 testing.

• Polyurethane foam insulation may be used as part 

of a roof over metal decks provided (1) a fire-rated 

underlay of perlite, gypsum board or other 

approved thermal barrier material is applied 

between the foam and the deck to provide protection from fire inside the building, (2) the roof 

assembly passes ANSI/UL 1256 or FM 4450, 

or (3) the roof assembly has earned the 

necessary approvals from building code 

officials and insurers based on results of 

acceptable diversified testing provisions 

of the codes. For example, polyisocyanurate foam roof insulation has been 

approved by both Underwriters 

Laboratories (UL) and Factory Mutual 

(FM) for installation direct to steel decks 

without a thermal barrier on the basis of 

ANSI/UL 1256 and FM 4450 fire tests.

• When used as an exterior insulating 

material on structures, such as tanks or 

chemical processing equipment, 

polyurethane or polyisocyanurate foam 

products also may require protection (1) 

from the weather and ultraviolet rays of 

the sun, (2) from severe physical impact, 

and (3) from accidental ignition. 

common means available today to comp

significant combustibility characteristics o

other materials of construction, and asse

tests and ratings also are used to commu

information to knowledgeable consumers

the tests and ratings are valid only as me

the performance of these materials and/o

under specific, controlled test conditions 

intended to reflect hazards under actual f

More than one test may be necessary to 

qualify a material for an intended or propo

Authorities having jurisdiction should be c

Fire Tests, Building Codes, and Standard

*This table only contains fire tests, building codes, and standards refer

Other tests, codes, and standards may apply. Always consult with auth

ANSI/UL 1256 Fire Test of Roof Deck Constructions

ASTM E-84 Standard Test Method for Surface Bur

Characteristics of Building Materials

ASTM E-108 Standard Test Method for Fire Tests o

FM 4450 Class 1 Insulated Steel Deck Roofs

FM 4880 Building Corner Fire Test Procedure

NFPA 51B Fire Prevention During Welding, Cutti

OSHA 29 CFR 1910 Occupational Safety and Health Stan

UBC Standard 26-3 Room Fire Test Standard for Interior 

UL 790 Tests for Fire Resistance of Roof Cove

UL 1040 Fire Test of Insulated Wall Constructi

UL 1715 Fire Test of Interior Finish
5

Additional Information

Information on the fire tests, building codes, and

standards may be obtained from:

American National Standards Institute (ANSI)

11 West 42nd Street

New York, NY 10036

212.642.4900

www.ansi.org

American Society of Testing and Materials (ASTM)

100 Barr Harbor Drive

West Conshohocken, PA 19428-2959

610.832.9585

www.astm.org

National Building Code

Building Officials and Code Administrators

International (BOCAI)

4051 West Flossmoor Road

Country Club Hills, IL 60478-5795

708.799.2300

www.bocai.org

Factory Mutual (FM)

1151 Boston-Providence Turnpike

Norwood, MA 02062

781.762.4300

www.fmglobal.com

y, 

617.984.7402

www.nfpa.org

Occupational Safety & 

Health Administration (OSHA)

Office of Public Affairs – Room N3647

200 Constitution Avenue

Washington, DC 20210

202.693.1999

www.osha.gov

Standard Building Codes

Southern Building Code 

Congress International (SBCCI)

900 Montclair Road

Birmingham, AL 35213-1206

205.591.1853

www.sbcci.org

Underwriters Laboratories Inc. (UL)

US Corporate Headquarters

333 Pfingsten Road 

Northbrook, IL 60062-2096

847.272.8800 

www.ul.com

Uniform Building Code (UBC)

International Conference of Building O

5360 Workman Mill Road

Whittier, CA 90601-2298

562.699.0541

www.icbo.org
This guide was developed by the Alliance for the Polyurethanes Industry (API), a business unit of the Ame

Council. It is intended to briefly summarize fire safety guidelines for use of rigid polyurethane and pol

foam insulation in building construction, as provided in good faith by API members. It is not intende

specific legal or technical advice, nor to endorse specific polyurethane or polyisocyanurate propriet

or processes, and is made WITHOUT WARRANTY, EXPRESSED OR IMPLIED AS TO MERCHANTABIL

FOR PARTICULAR PURPOSE, OR ANY OTHER MATTER. Persons setting up polyurethane or polyiso

operations should consult with their own technical and legal advisors and appropriate sources of fir

©2003 American Plastics Council Doing Business As the Alliance for the Polyurethanes Industry

g, 

703.253.0700

www.sprayfoam.org

www.plastics.org

6

ALLIANCE FOR THE

POLYURETHANES

INDUST RY

A BUSINESS UNIT OF THE AMERICAN PLASTICS COUNCIL

1300 WIL

ARLIN

703.741.5656 FA

www.polyurethane.org