According to China's national standard "Code for Fire Protection Design of Buildings", the fire resistance rating of buildings is divided into four levels. The fire resistance grade of a building is determined by the combustion performance and fire resistance limit of building components (beams, columns, floors, walls, etc.). ). Generally speaking, the first-class fire-resistant building is a reinforced concrete structure or a mixed structure composed of brick walls and reinforced concrete structures; The second type of fire-resistant building is a mixed structure composed of steel roof truss, reinforced concrete column or brick wall; The third-class fire-resistant building is a brick-wood structure, consisting of a wooden roof and a brick wall; The fourth-class fire resistance rating is a combustible structure consisting of a wooden roof and a fire-resistant wall. Roof waterproofing is divided into Ⅰ-Ⅳ categories, of which permanent works are divided into Ⅰ-Ⅲ categories. Class I fortification refers to projects that are particularly important and have special requirements for waterproofing, such as the National Center for International Political Activities, the National Museum, the Archives, the International Airport and important memorial buildings, such as the Great Hall of the People, the State Guesthouse, the National Library and the Palace Museum. Buildings that affect the international reputation, as well as places of use and industrial building warehouses that will cause irreparable losses to treasures once leaked. The second-class fortification is the most important building and high-rise building, such as large public buildings, important museums, libraries, hospitals, star-rated hotels, theaters, auditoriums, stations, large factories, constant temperature and humidity workshops, laboratories, villas and so on. , including 12 storey high-rise buildings, with a reasonable service life of 15 years. The third level refers to general buildings, including general industrial and civil buildings, general houses, general office buildings, schools, hotels and so on. The reasonable service life is 10 year. Grade IV is temporary and permanent buildings, such as simple dormitories, workshops and temporary waterproof buildings, which are planned to be rebuilt. The reasonable service life is limited to five years.