# Code Definition of Combustible



## retire09 (Dec 12, 2011)

What is the code definition of combustible?

Is there a  temperature rating or anything specific that can be used for the determination?


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## mark handler (Dec 12, 2011)

Not Code, but: Capable of igniting and burning.


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## gbhammer (Dec 12, 2011)

In the National Fire Protection Association's NFPA 101 Code for Safety to Life from Fire in Buildings and Structures, a noncombustible material is defined as a material that, "in the form in which it is used and under the conditions anticipated, will not aid combustion or add appreciable heat to an ambient fire." Materials are tested for noncombustibility in ASTM E 136 Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 deg. C. The test exposes small samples of the material to a stream of air heated to 750 deg. C, (1382 deg. F). The material is deemed noncombustible if: 1) Sample temperatures at no time exceed 780 deg. C, (1436 deg. F).

2) There is no flaming after 30 seconds. 3) Once the sample loses 50% of its weight, there is no flaming and sample temperatures never exceed 750 deg. C, (1382 deg. F). ASTM E 136 is an extremely strict test and under its criterion, few building materials qualify as noncombustible. Two USG Interiors products which do are CERAMIC HERITAGE and most THERMAFIBER insulation products.


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## cda (Dec 12, 2011)

09;;;;

Combustible , combustible????

Or

Combustible liquid???


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## mark handler (Dec 12, 2011)

cda said:
			
		

> 09;;;; Combustible , combustible???? Or Combustible liquid???


NFPA 30

a combustible liquid is one whose flash point is 100°F or higher


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## Dr. J (Dec 12, 2011)

As CDA indicated there are different "combustibles", liquids, solids, dusts, fibers.  Also, which code?

IBC uses the ASTM 136 test, but also allows "composite materials" to be accepted as non-combustible if the base material is non-combustible as long as the facing is less than .125" and a flame spread of 50 or less.  This allows gypbd to be considered non-combustible by the IBC, otherwise a ASTM 136-only test would render gypbd as combustible.

IMC does not have the composite exception, therefore gypbd is considered combustible for things addressed in the IMC.

NFPA 101 has a category for "Limited Combustible" which is similar to the composite exception in IBC.

As gb indicated, this is a very tough test, and many common building materials not capable of igniting or burning do not meet it or are not suited to be tested to that standard (aluminum).

For liquids, NFPA, IBC, and IFC liquids having flash point at or over 100 deg F are combustible.  Under 100 deg F is considered Flammable.


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## mtlogcabin (Dec 12, 2011)

2009 IMC

COMBUSTIBLE MATERIAL. Any material not defined as noncombustible.

NONCOMBUSTIBLE MATERIALS. Materials that, when tested in accordance with ASTM E 136, have at least three of four specimens tested meeting all of the following criteria:

1. The recorded temperature of the surface and interior thermocouples shall not at any time during the test rise more than 54ºF (30ºC) above the furnace temperature at the beginning of the test.

2. There shall not be flaming from the specimen after the first 30 seconds.

3. If the weight loss of the specimen during testing exceeds 50 percent, the recorded temperature of the surface and interior thermocouples shall not at any time during the test rise above the furnace air temperature at the beginning of the test, and there shall not be flaming of the specimen.

My understanding is gypsum board will not meet this definition and that is why gypsum board is always mentioned in conjunction with clearances to combustible construction with regards to hoods and grease ducts. A product may be non-combustible in one application and combustible in another.

Sorry Dr J did not see your post


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## Coug Dad (Dec 12, 2011)

UBC had a great definition of "noncombustible".  I wonder why it did not make it into the IBC


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## steveray (Dec 13, 2011)

The fine folks above nailed it superbly...the 136 test was the first thing that came to my mind....keep in mind as MT and Dr J said there are only 2 ways for some of those items to be considered non-combustible....certain things fire treated wood are not! (That I am aware of at this time) I see alot of people trying to use it for raised floors in noncombustible buildings....


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## FM William Burns (Dec 13, 2011)

I agree with others as to the differences with and in combustible “materials”. I could give you the definition from a fire science resource material on behavior but here is one that essentially combines all of them and is from NFPA 921

A.3.3.28 Combustible.

A.3.3.28 Combustible. A combustible material is capable of burning, generally in air under normal conditions of ambient temperature and pressure, unless otherwise specified; combustion can occur in cases where an oxidizer other than the oxygen in air is present (e.g., chlorine, fluorine, or chemicals containing oxygen in their structure).

3.3.72 Flammable.

Capable of burning with a flame.

Again different characteristics for types of combustibles and flammables based on the material and exposure to heat before they fall into one category or the other.

Do the codes not allow one to use Webster’s when not specifically defined?


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## gbhammer (Dec 13, 2011)

steveray said:
			
		

> The fine folks above nailed it superbly...the 136 test was the first thing that came to my mind....keep in mind as MT and Dr J said there are only 2 ways for some of those items to be considered non-combustible....certain things fire treated wood are not! (That I am aware of at this time) I see alot of people trying to use it for raised floors in noncombustible buildings....


It never fails to amaze me when some one tries that.


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