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Safety Standards for Foam Plastics - Thermal and Ignition Barriers

 

Occupied and Unoccupied Spaces

See Also: Barrier Manufacturers List - Fire/Thermal Barrier FAQs

The International Building Code (2006 IBC) requires foam plastic insulation to be separated from the interior of a building by an approved thermal/fire barrier of 1/2-inch gypsum wallboard or equivalent thermal barrier that will prevent temperature rise to not more that 250 degrees F (121 C) in a 15-minute time period. Codes regulating unoccupied or inaccessible areas, such as attics or crawlspaces, require that combustible building materials be protected against ignition. Other exceptions exist for special constructions and assemblies.

The 15-minute period is thought to typically be a sufficient time for occupants to escape from a building before they can be trapped, or overcome by smoke from burning wood, plastic or other construction and finish materials. Historically, code regulations regarding thermal barriers apply to occupied areas of commercial buildings, but have often been followed as safety guidelines for residential structures by local code officials.

The table below lists a variety of building materials and spray coatings used as thermal barriers, as well as those that provide protection from ignition. The chart includes the minimum thickness, where applicable, of the material required by code for occupied and unoccupied space. Fire barrier information provided here is for informational purposes only. Before proceeding, consult your local building code or inspector. While decisions made within one code jurisdiction may be considered as a precedent for others, the final decision on materials, not specifically listed in the code, are usually made on a case-by-case basis within each jurisdiction.

See Section 2603 of the IBC “Foam Plastic Insulation" for more detailed information.

Materials for Thermal and/or Ignition Protection

The information below is believed to be reliable and has been provided by manufacturers, independent third-party research, and governmental agencies. Although the research is compiled and presented by Building Envelope Services, Inc./FOAM-TECH, neither assumes any guarantee, warranty or responsibility of any kind, expressed or implied. As in the cases of MSD Sheets, please contact the original manufacturer for most recent updates. Note that some thermal and ignition barriers are tested for use with foam plastic insulation of limited thickness and density, and only in specific (vertical, horizontal, sloped, etc.) orientations.

15-Min. Thermal Barrier

(Occupied Space)

Protect from Ignition

(Attic & Crawl Space)

Material
IC
IM
PA
IC
IM
PA
C

Wood structural panel sheathing or tongue & groove planking

15/32"

X

Wood Boards

≥ 5/8"

 1/4"

Particle Board, Plywood

15/32"

X

OBS sheating* 

15/32"

 1/4"

Sheetrock Gypsum Wall Board

1/2"

3/8"

Lath and Plaster  - 5/8"

5/8" – 3⁄4"

X

Steel - Base Metal

.016

.016

Aluminum - Base Metal

.032

.032

Mineral Fiber Insulation

2"

1-1/2"

Rated Grid Suspended Ceiling System

5/8"

X

Monokote® (spray coating)
W.R. Grace Co.

3/4"

X

Zonolite®
(spray coating)

3/4"

X

Stayflex" (spray coating)
Preferred Solutions, Inc.

1/16" – 1/8"

X

K-13" (spray coating) National Cellulose Co.  (and similar products)

1 – 1/2"

X

Gunnite  (spray coating)

X

X

NTEC
(spray coating)

X

Thermax

X

X

Intumescent Paint

X

Exposed w/sprinkler

X

X

Masonry or concrete construction - 1" or more

X

X

 

IC = Identified in Code

PA = Previously Approved

IM = Identified by Manufacturer

C = Consistent with the intent of the code

* As part of an assembly

 

Related Information

Barrier Manufactures List - Fire/Thermal Barrier FAQs

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