Flame spread or surface burning characteristics rating is a ranking derived by laboratory standard test methodology of a material

Material

Material is anything made of matter, constituted of one or more substances. Wood, cement, hydrogen, air and water are all examples of materials. Sometimes the term "material" is used more narrowly to refer to substances or components with certain physical properties that are used as inputs to...

's propensity to burn

Burn

A burn is an injury to flesh caused by heat, electricity, chemicals, light, radiation, or friction.Burn may also refer to:*Combustion*Burn , type of watercourses so named in Scotland and north-eastern England...

 rapidly and spread flame

Flame

A flame is the visible , gaseous part of a fire. It is caused by a highly exothermic reaction taking place in a thin zone...

s. There are several standardized methods of determining flame spread,

Test Methods

NFPA 255 Standard Method of Test of Surface Burning Characteristics of Building Materials, utilizes ASTM E 84 Standard Test Method for Surface Burning Characteristics of Building Materials. This test method measures flame growth on the underside of a horizontal test specimen. The result is derivation of a Flame Spread Index (FSI), which is a non-dimensional number which is placed on a relative scale in which asbestos-cement board has a value of 0, and red oak wood has 100. Evaluation of a FSI by this test method does not provide a good understanding of how fire would propagate in full scale, such as in a room, for some materials. In particular, the results for materials that drip, such as thermoplastics, are not indicative of the fire hazard as installed on walls and ceilings because they tend to melt and drip away from the underside of the horizontal ceiling in the test chamber. Because the test method measures how far down the test chamber the fire progressed, this type of "lack of fire progression" provides a misleading FSI. In order to address such restrictions, a new test method was derived, NFPA 286 Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth.

NFPA 286 Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth, measures flame spread in a room configuration, including fire spread along walls, ceilings, and combinations of both. This method is more indicative of real world fire hazards, and is preferred over NFPA 255, but is more expensive. Also, test results for heat, smoke

Smoke-developed index

Smoke-developed index is a measure of the concentration of smoke a material emits as it burns. Like Flame Spread Index, it is based on an arbitrary scale in which asbestos-cement board has a value of 0, and red oak wood has 100....

, and combustion product release from NFPA 286 are suitable for use as input into fire models for performance-based design, whereas results from NFPA 255 are not.

Use

The Life Safety Code

Life safety code

Administered, copyrighted, and published by the National Fire Protection Association , the Life Safety Code, known as NFPA 101 is the registered trademark of an American consensus standard which, like many NFPA documents, is systematically revised on a three year cycle.The standard, despite its...

 groups flame spread ratings into five classes. Section 803.1 of the International Building Code

International Building Code

The International Building Code is a model building code developed by the International Code Council . It has been adopted throughout most of the United States.-History:...

limits finishes for interior walls and ceilings to materials in just the first three classes, and gives greater restrictions for certain rooms:

NFPA	IBC	rating
A	A	0-25
B	B	26-75
C	C	76-200
D	-	201-500
E	-	over 500