Look at the property ownership certificate. A stacked villa is a combination of two independent villas stacked together. It is a combination of multi-story duplex houses stacked up and down. It is a 4-5-story building with a loft. For the ownership of the space under the stairs in a stacked villa, please refer to the property rights certificate. There is a picture on it to confirm the area and scope of the property rights belonging to you. If it is not written, you can further check the contract stipulations.