Abstract: A sectional folding overhead door assembly that includes a pair of opposite, vertically disposed side supports and guides defining a door opening between them, each of the supports and guides including a first channel and a second channel disposed side-by-side, a door component having a first, second, third and fourth rectangular panel adapted for folding vertical movement along the supports and guides, a folding movement controlling member, each folding movement controlling member having a folding movement controlling member upper end hingeably connected to a respective side edge of the first and third panels, respectively, and a folding movement controlling member lower end hingeably connected to the respective guide plate lower end around a folding movement controlling member hinge axis, and a folding movement guiding channel into which a respective side plate guiding pin of a side plate attached to the second panel extends.