Class B thermal insulation materials can be divided into three grades, among which Class B1 is flame retardant, class B2 is combustible and class B3 is flammable. Class B1 belongs to flame retardant insulation material, and EPS / XPS insulation board with special treatment and flame retardant is more common. Flame retardant materials have good flame retardancy. In case of open fire in the air or under the action of high temperature, it is difficult to catch fire and is not easy to spread, and the combustion stops immediately after the fire source is removed.
Class B2 is combustible thermal insulation material, which is mostly benzene board, extruded board, polyurethane, ordinary real gold board, etc. This material has a low ignition point and will release a large number of harmful gases during combustion. Although combustible materials have a certain flame retardant effect, they will catch fire immediately in case of open fire in the air or under the action of high temperature, which is easy to lead to the spread of fire, such as wooden columns, wooden roof frames, wooden beams, wooden stairs, etc. Grade B3 is a flammable thermal insulation material, mostly polystyrene foam material as the main insulation material. Without any flame retardant effect, it is very easy to burn and has great fire risk.
(1) When the exterior wall external insulation system of the building adopts thermal insulation materials with combustion performance of grade B1 and B2, it shall comply with the following provisions: except for public buildings with grade B1 thermal insulation materials and building height of no more than 24m or residential buildings with grade B1 thermal insulation materials and building height of no more than 27m, the fire resistance integrity of exterior wall doors and windows shall not be less than 0.50h. Each layer of the insulation system shall be provided with a horizontal fire isolation belt. The fireproof isolation belt shall be made of materials with class a combustion performance, and the height of the fireproof isolation belt shall not be less than 300mm.
(2) The external thermal insulation system of the external wall of the building shall adopt incombustible materials, and a protective layer shall be set on its surface, which shall completely cover the thermal insulation materials.
(3) The decorative layer of the external wall of the building shall be made of materials with class a combustion performance, but Class B1 materials can be used when the building height is not greater than 50m.
(4) For the external thermal insulation system of the building roof, when the fire resistance limit of the roof panel is not less than 1.00h, the combustion performance of the thermal insulation material shall not be lower than grade B2; When the fire resistance limit of roof slab is lower than 1.00h, it shall not be lower than grade B1. The external insulation system with B1 and B2 thermal insulation materials shall use incombustible materials as the protective layer, and the thickness of the protective layer shall not be less than 10mm. When B1 and B2 thermal insulation materials are used for the roof and external wall external insulation system of the building, non combustible materials with a width of not less than 500mm shall be used between the roof and external wall, and fireproof isolation belt shall be set for separation
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