What is the fire resistance classification?

Fire protection grade is a method of classifying materials based on their ability to support and spread the fire, and also indicates the smoke produced by the material. This is determined by the flame diffusion index.

The flame propagation index is numerical and is usually obtained by checking the response of the material during a 10 minute tunnel test. The fire spread index value is expressed by any value of 0 for asbestos cement board and 100 for red oak.

Each fire classification is assigned a set of flame diffusion indices. A basic understanding of fire resistance assessment of structural elements is very helpful in protecting assets from fire. These are the levels recognized by the National Fire Protection Association's Life Safety Code NFPA No. 101.

What is a Class A or Class 1 Fire Rating?

Class 1 fire resistance is the highest fire resistance of any achievable material. Class A fire resistance means that the flame spread rating is 0-25.

Materials classified as Class A or Class 1 include brick, gypsum wallboard, and fiber cement exterior wall materials. These materials do not burn well and are unlikely to be fuel for fire.

What is Class B or Class 2 fire resistance?

Class B or Class 2 fire resistance is the second best class on the list. Class B flame propagation ratings are between 26 and 75. This grade is a typical all-wood material with a slow burning rate.

The material of the perfect wood is a board, the shape of which is the same as when cut from wood. They burn faster than Class A materials and slower than Class C materials.

What is a C or 3 fire rating?

The flame propagation rating for Class C or Class 3 fire protection is between 76 and 200. This grade includes construction materials such as plywood, fiberboard and hard siding. It also includes the entire tree that burns faster.

Grades 201-500 are considered D-level materials, and E-level materials include all materials with a flame diffusivity greater than 500. Classes D and E are not considered valid for any form of fire exposure.

What is the difference in fire resistance between Class 1 and Class 0?

You may have seen class 1 and class 0 fire protection grades used interchangeably to some extent. They are very similar and level 0 is essentially an improvement on level 1 material.

To qualify for Class 0, the material must first meet Class 1 but must also contain a coating that does not contribute to fire. The material usually requires at least one layer of expansive paint or varnish that expands or burns when heated, and at least one layer of flame paint.