• The problem of ventilation and drainage by conventional plumbing is an important factor in determining the ceiling height because of the interference with the complicated plumbing in the ceiling inside the building.



• Pre-existing methods are also at odds with drainage system designers' desire to elimi- nate even a single piece of piping inside the ceiling of a building as much as possible.



• When designing and constructing with this new vent drain method, the drain strainer can be installed directly at the location of the bathroom, washbasin, and other drains on the foundation slabs on each floor. It is more economical to use this new vent drain construction by simplifying the complicated internal plumbing work and reducing various material costs, labor costs and construction costs compared to the pre-existing drainage and drain construction.