I’m about to take over the property soon; I’d appreciate some advice from experts

See \"Code for Calculation of Building Area in Construction Projects GB/T50353-2005\"

What was said upstairs is correct; calculations should be carried out in accordance with the \"Code for Calculating the Building Area of Construction Projects\"! !

The usable area refers to the interior area of the unit; the sales area of a house usually denotes the total building area (although there are also cases where it is sold based on the usable area, as I heard in Chongqing). The total building area consists of the usable area, the structural area, and the shared areas. The structural area refers to half of the cross-sectional area of the unit wall. The shared area refers to the portion of common facilities that is shared among residents, such as the area of the building’s stairwells, pipe shafts, and utility rooms. This is how I understand it; I’m not sure if it’s correct Let’s discuss together

The \"Code for Calculating the Building Area in Construction Projects\" only outlines the methods for calculating the building area, without explaining concepts such as the usable area. Useful area: refers to the area that is actually used; it is the building area minus the shared areas and the area occupied by walls. The sales area of a property is generally the building area, which includes the useful area, the area occupied by walls, and the shared areas. In fact, it is the area indicated on your final property title, which is also the area you purchased at a certain price per square meter. The usable area of residential units on higher floors is generally 85% of the total building area. It should be noted that the shared areas do not include the area occupied by walls.

The usable area, plus the area of the interior walls, plus the shared area equals the total building area. However, the area of the interior walls varies depending on the type of apartment, and the shared area cannot be determined as it differs from one building to another; therefore, this ratio is not fixed. The approximate range is as follows: For multi-story buildings, it is 100:85; for high-rise buildings, it is 100:75. In terms of floor area, the sales area of commercial housing refers to the sum of the interior floor area of the unit or apartment purchased by the buyer (hereinafter referred to as the interior floor area) and the shared common area. Commercial housing is sold in units of “apartments” or “units”. When selling commercial housing, the seller must clearly state the sales area of the housing, as well as the interior floor area of the unit and the shared area that should be allocated to it. The unit of measurement for the sales area of commercial housing should be square meters. The difference between the sales area of commercial housing and its actual area shall not exceed the allowable measurement tolerance for the area of such housing as specified in the measurement technical standard \"Measurement and Calculation of Sales Areas for Commercial Housing\". For commercial housing sold by unit or apartment, the sum of the sales areas of all such units or apartments shall not exceed the actual total area of the entire building. 2. The interior construction area of a residential unit: The interior construction area of a commercial residential unit refers to the sum of the usable interior area, the area occupied by interior walls, and the area of balconies within that unit. The indoor floor area is not equal to the carpeted area; it belongs entirely to the home buyer as personal property ； Compared to the usable area within the unit, it reflects more accurately the ownership of the buyer’s private space. The formula for calculating the indoor usable area is as follows: Indoor usable area = Indoor usable space area + Area of interior walls + Area of balconies. 3. Indoor usable space area: The indoor usable space area refers to the area of the spaces within the house that can be used, and it is calculated according to the following rules: (1) The indoor usable space area is the sum of the areas of bedrooms, living rooms, corridors, kitchens, bathrooms, storage rooms, wardrobes, and other such spaces within the house ； (2) The area of the internal stairs is included in the usable area based on the total area of all floors ； (3) Chimneys, ventilation ducts, and pipe shafts that are not included in the structural area are all counted as part of the usable area ； (4) The thickness of interior wall decorations is included in the usable area. 4. Area of interior walls: The area of interior walls refers to the area occupied by the retaining or load-bearing walls surrounding the usable space within each unit of a commercial property. The interior layout of commercial housing is divided into shared walls and non-shared walls. The method for calculating the interior wall area of commercial housing units is as follows: (1) Shared walls include the partition walls between different units, the walls that separate each unit from the projected area of common building spaces, as well as the exterior walls (including gables) ； Half of the horizontal projected area of the shared wall is included in the area of the interior walls. (2) The horizontal projected area of all non-shared wall surfaces is included in the interior wall area. 5. The floor area of the balcony within the unit is calculated in accordance with the provisions of the \"Rules for Calculating Building Area\", based on the horizontal projected area between the perimeter of the balcony and the exterior wall of the building. Among them: (1) The originally designed enclosed balcony has its building area calculated based on the horizontal projected area of its perimeter ； (2) The building area of the pick balcony (bottom balcony) is calculated as half of the horizontal projected area of its base slab ； (3) The floor area of a recessed balcony is calculated as half of its net area (including the area of the partition walls) ； (4) For balconies that are partly protruding and partly recessed, the building area of the protruding part is calculated as half of the horizontal projected area of its base, while the building area of the recessed part is calculated as half of its net area. 6. Common area area: The allocation of the common area area in commercial housing is done on a building-by-building basis. The allocated common area area refers to the common area area within each building. The common area space that is not connected to this building shall not be allocated to the residents of this building; instead, it shall be shared among the individual commercial units in that building ； The common building area that serves a specific area is shared among the individual commercial housing units that benefit from it. The shared common area area for each set of commercial housing is the sum of the shared common area areas per household.

I’m about to buy a house too; I’ve started learning*. It’s a bit complicated though; will the developer tell us how to do it, or should we calculate it ourselves? No, don’t go to which department to resolve it.

There are calculation guidelines, but they are too opaque.

There’s no need to calculate this; it’s already all figured out, and even if you try to calculate it yourself, you won’t be able to figure it out. Anyway, it’s whatever is written on the property title. If the area specified in the purchase contract is incorrect, the difference will be refunded or compensated when the property certificate is issued~~~~~~