The apartment that was constructed this time was not carried out with the entire interior construction before moving in, but was already replaced with a folding door in the Mi-seo window while living. Since home appliances and furniture are already located, it is difficult to remove and construct all frames such as lower rails. Therefore, the existing high-shot seat should not be demolished, but only the window should be demolished by the construction method of the demolition lower rail.

Construction is carried out by inserting the folding door lower rail on top of the normal glass middle door (high shot). There are people who are worried that the lower rail jaw will get higher. The height remains the same by combining the existing lower shot. This lower rail construction method does not remove the existing shot seat, so there is no additional cost of demolition, and there is no damage to wallpaper, floor plate, marble, etc. already under interior construction.

It is a construction method that does not require demolition work, and the installation of folding doors proceeds quickly, and this construction method is also called "one-day construction method."