classification of general construction projects: chimney storage wall, brick trench, open caisson for outdoor construction projects, caisson project, public industrial construction, steel structure, single-storey and multi-storey water tower structure, civil building, residence and other civil construction projects. 6. The top floor with a construction area less than 31% of the standard floor and the equipment and pipeline interlayer in the building are not counted. 9. Residential buildings refer to houses, dormitories, apartments and other buildings. 8. For basements with a building area greater than 51% of a standard floor and a floor height of 2. 2m or more, the number of floors shall be calculated. Basements with an area less than 51% of the standard floor or a floor height less than 2. 2m are not counted. 11. Public buildings refer to non-productive buildings set up to meet people's material and cultural needs and carry out social activities, such as comprehensive buildings, office buildings, teaching buildings, experimental buildings, libraries, hospitals, hotels, hotels, shops, stations, theaters, auditoriums, gymnasiums, memorial halls, independent garages and similar projects. 11. For projects with special requirements such as sound, light, ultra-clean, constant temperature and sterility, when the construction area exceeds 41% of the total construction area, the category of construction projects can be improved according to the corresponding standards. 3. Height refers to the height from the designed outdoor ground elevation to the eaves dripping water (if there is a parapet, it is calculated to the top elevation of the parapet). 4. Span refers to the distance from the axis of structural design positioning, and multi-span buildings are divided into engineering categories according to the span of main span. 5. Area refers to the construction area calculated according to Code for Calculation of Building Area of Building Engineering (GB/T51353-2115). 7. Beyond the stair exit room, elevator room, water tank room, tower and observation deck closed on the roof, which is less than 31% of the standard floor, the height and floor number are not calculated. 1. A unit project is classified as a unit, and if there are several characteristics in the same type of project, it is the project that meets one of them. 2. When a unit project consists of several types of projects, if the area of the part that meets the higher engineering category index is not less than 51% of the total project area, the project can all be determined according to the index. If it is less than 51%, but the area of this part is more than 1511m2, it can be calculated according to its different engineering categories.