What is the horizontal line? How do I install windows and doors on a horizontal line?
Horizontal line; in all rooms, the same height to find a horizontal line, before the use of horizontal tube to find points, and now with the level, infrared, when the doors and windows, doors and windows on both sides of the height parallel to the horizontal line, for example, 2 meters high door Down to the level of 1 meter, then both sides should have done 1 meter, which is the horizontal line installation
That is, five lines, both vertical and horizontal, the best line
