The burning properties of building materials refer to all physical and chemical changes that occur during combustion or fire. This property is caused by the ignitability and flame spread of the surface of the material, heat generation, fuming, charring, weight loss, and toxic products. According to the generation of other characteristics to measure, China's national standard GB8624-97 divides the burning performance of building materials into the following levels:
Class A: Non-combustible building materials: Materials that hardly burn.
Grade B1: Flame retardant building materials: Flame retardant materials have good flame retardant effects. It is difficult to catch fire when exposed to fire in the air or under high temperature, and it is not easy to spread quickly, and the combustion stops immediately after the fire source is removed.
Class B2: Combustible building materials: Combustible materials have a certain flame retardant effect. When exposed to fire in the air or under high temperature, they will immediately ignite and burn, which may lead to the spread of fire, such as wooden columns, wooden trusses, wooden beams, and wood. Stairs, etc.
Grade B3: Flammable building materials: no flame retardant effect, extremely flammable, and dangerous to fire.