The building plan is a horizontal sectional view obtained by cutting horizontally above the window sill of the house, removing the upper part and using it for the orthographic projection of the rest. The construction drawing of a building project, referred to as "construction drawing" for short, is a drawing that shows the overall layout of the project, the external shape of the building, the internal layout, the structural structure, the internal and external decoration, the material method, the equipment and the construction requirements.