The chassis consists of one or two general opening and closing doors depending on the general glass window and the floor space, but the entrance space is not spacious, and the access space cannot be increased further with the large fixed glass. As the use of veranda space is becoming more diverse these days, many people are thinking about the folding door installation due to the lack of utilization such as decorating the veranda space with a common shot-up of apartments. The expansion of the living room may have the advantage of expanding the living room due to the inconvenience of the general gate, but it cannot be used as a separate space and as an independent space, it cannot be used as a place of one's own or a hobby space.Using folding doors instead of regular veranda mid-door shots results in more than 90% of opening and closing, increasing space scalability and utilization.

The existing shot sheet is not removed, but only the windows and doors are removed.

Construction is carried out by inserting the folding door lower rail over the general glass middle door (high shot). Some people are worried that the lower rail jaw will be raised, but the height will remain the same by combining it with the existing lower shot.

As the lower rail construction method does not remove the existing shot sheet, there is no additional cost of removal, and there is no damage to the wallpaper, floorboards, marble, etc., which have already been constructed. The construction method does not require demolition work, and the folding door installation time is fast and this construction method is also called the "one-day construction method".